Chapter 10 Equilibrium

What is the common ion effect?

when a slightly soluble salt is added to a solution which already contains one of its components the added salt is less soluble than if it were added to a pure solvent

Is perchlorate water soluble

yes

osmotic pressure equation

Π = iMRT; Π = Osmotic pressure; i = # of molecules obtained from solvation; M = Molarity; R = Ideal gas constant; T = temprature

Addition of which of the following salts will most likely result in a precipitate when mixed with an aqueous solution of AgNO3? A. NaCl B. Mg(ClO4)2 C. Hg(NO3)2 D. NaCH3COO

A

Given the reaction below: FeI (aq) + I2 (g) → FeI3 (aq) Which of the following would increase the formation of product? A. Decreasing the volume of the container B. Decreasing the pressure of the container C. Increasing the volume of the container D. Decreasing the volume of the container while maintaining a constant pressure

A

If a sample of barium hydroxide (Ba(OH)2) is partially dissolved in pure water at room temperature. If the equilibrium concentrations of Ba2+ and OH- ions are measured, which of the following expressions could be used to find the solubility product for barium hydroxide? A. Ksp = [Ba][OH]2 B. Ksp = 2[Ba][OH]2 C. Ksp = 2[Ba][OH] D. Ksp = [Ba][OH]

A

hen is the reaction quotient equal to the equilibrium constant? A. When ΔG = 0 B. When the forward reaction has stopped C. When the reverse reaction has stopped D. When product concentrations are equal to reactant concentrations

A;

A sealed container contains NO2, a brownish-red gas, and N2O4, a colorless gas, at equilibrium at 0°C according to the following reaction: . How will the color of the gas mixture change if the container is placed in dry ice and acetone at -78°C? A. The gas mixture will become lighter in color. B. The gas mixture will become darker in color. C. Cannot be determined from the information provided. D. The gas mixture's color will not change because it is in equilibrium.

A; A sealed container contains NO2, a brownish-red gas, and N2O4, a colorless gas, at equilibrium at 0°C according to the following reaction: . The gas mixture will become lighter in color if the container is placed in dry ice and acetone at -78°C. The system is at equilibrium at 0°C, so ΔG must equal 0. We also know that during the forward reaction 2 moles of gas are converted to 1 mole of gas, which results in a decrease in entropy (ΔS < 0). From this, the sign of ΔH can be determined because ΔG = 0 = ΔH - TΔS. Solving for ΔH gives us: ΔH = TΔS. ΔH must be negative for the forward reaction because ΔS is also negative. Since the forward reaction is exothermic, it will be thermodynamically favored by a decrease in temperature. As temperature falls, the reaction shifts to the right. N2O4 (colorless) increases and NO2 (brownish-red) decreases, leading to an overall lighter color.

The water solubility of MgSO4 is approximately 25 g/100 mL at 20 degrees. Compared to a .25 g/mL solution of MgSO4 prepared at 20C, a .25 g/mL solution at 27 C will: A. Dissolve faster and have the same concentration of ions in solution. B. Dissolve faster and have a higher concentration of ions in solution. C. Dissolve slower and have a lower concentration of ions in solution. D. Dissolve slower and have the same concentration of ions in solution.

A; Any time temperature is increased, the reaction kinetics increase. In this case, the salt will dissolve faster, eliminating choices C and D. Both solutions contains the same amount of MgSO4 that does not exceed the maximum solubility at either temperature. Therefore, concentrations are the same.

If the molar solubility of O2 in water is 2.59 x 10-4M at sea level and 25°C, what is the molar solubility of O2 at an elevation of 6,225 ft where atmospheric pressure is 0.805 atm at 25°C? A. 2.08 x 10-4M B. 2.59 x 10-4M C. 3.66 x 10-4M D. 4.06 x 10-4M

A; At higher elevation, atmospheric pressure is lowered, which decreases the solubility of a gas in solution. Choice A is the only option with a lower molar solubility than the one given in the question.

Barium chromate solid (Ksp = 1.2 x 10^-10) is at equilibrium with its dissociated ions in an aqueous solution. If calcium chromate (Ksp = 7.1 x 10^-4) is introduced into the solution, it will cause the molar quantity of: A. Solid barium chromate to increase and barium ion to decrease B. Solid barium chromate to increase and barium ion to increase C. Solid barium chromate to decrease and barium ion to decrease D. Solid barium chromate to decrease and barium ion to increase

A; The introduction of an additional chromate ion - the common ion - will cause the amount of barium ion in solution to decrease

When CaF2 is added to a 0.02 M solution of NaF, the solubility of CaF2 is: A. low, because the concentration of F- already present in solution prevents dissolution of CaF2. B. high, due to the common ion effect. C. low, because less water is available for solvation due to the presence of NaF. D. unaffected by the presence of sodium fluoride.

A; When CaF2 is added to a 0.02 M solution of NaF, the solubility of CaF2 is low, because the concentration of F- already present in solution prevents dissolution of CaF2. The addition of dissolved F- (by adding NaF) decreases the solubility of CaF2. This is the common ion effect (Le Châtelier's principle).

The solubility product is simply what?

Another equilibrium constant

Which procedure below can be used to prepare a 0.75 M solution of KC2H3O2(aq) (MW = 98 g/mol)? A. Dissolve 98.0 g of KC2H3O2 in 750 g of water. B. Dissolve 146 g of KC2H3O2 in enough water to make 2.0 L of solution. C. Dissolve 73.5 g of KC2H3O2 in enough water to make 750 mL of solution. D. Dissolve 73.5 g of KC2H3O2 in 1000 g of water.

B

Consider the following two reactions: 3 A + 2 B <--> 3 C + 4 D (Reaction 1) 4 D + 3 C <--> 3 A + 2 B (Reaction 2) If Keq for reaction 1 is equal to 0.1, what is Keq for reaction 2? A. 0.1 B. 1 C. 10 D. 100

C

If carbon dioxide gas is in equilibrium with an aqueous solution of carbonic acid, then the CO2solubility can be increased by: A. decreasing the pH. B. increasing the temperature. C. increasing the pressure. D. adding carbonic anhydrase, an enzyme which increases the rate of the dissolution reaction of CO2 in water.

C

Of the following, which is the weakest electrolyte? A. NH4I B. LiF C. AgBr D. H2O2

D

What does it mean when Qsp > Ksp

Excess will precipitate

How do you increase the solubility of gases in liquids?

Increase pressure

How do you decrease solubility of gases in liquids?

Increase temperature

How do you increase the solubility of solids in liquids?

Increase temperature

N2(g) + 3 H2(g) 2 NH3(g), ΔH = -22 kcal/mol Increasing the temperature of the reaction at equilibrium will most likely: A. increase the forward reaction. B. increase the heat of reaction. C. decrease the heat of reaction. D. decrease the forward reaction.

Increasing the temperature of the reaction at equilibrium will most likely decrease the forward reaction. Since the heat of reaction (ΔH) is not a function of temperature, it will not increase or decrease the heat of reaction. Since the reaction is exothermic, Le Châtelier's principle implies that increasing the temperature will decrease the forward reaction.

What effect does adding an inert gas at constant volume do to a reaction?

Inert gas will not participate in the reaction

Are hydroxides soluble or insoluble?

Insoluble except sodium, potassium and calcium

equilibrium constant equation

Keq = [products]/[reactants] For the reaction A + B <--> C + D Keq = [C]^c[D]^d / [A]^a[B]^b

What is the solubility product constant?

Ksp, the extent to which a salt will dissolve in water

What is the reaction quotient?

Same calculation for equilibrium constant except without equilibrium concentrations. Comparing Q with Keq tells us which direction the reaction will proceed in.

What effect does the common ion effect have on equilibrium?

Shifts it to the left

Consider the reaction: N2 (g) + 3 H2 (g) <--> 2 NH3 + heat What effect does adding ammonia (product) due to the reaction?

Shifts left Q > Keq

Consider the reaction: N2 (g) + 3 H2 (g) <--> 2 NH3 + heat. What effect does removing nitrogen (reactant) have on the reaction?

Shifts left Q > Keq

Consider the reaction: N2 (g) + 3 H2 (g) <--> 2 NH3 + heat What effect does removing ammonia (product) have on the reaction?

Shifts right Keq > Q

Consider the reaction: N2 (g) + 3 H2 (g) <--> 2 NH3 + heat What effect does adding hydrogen gas (reactant) have on the reaction?

Shifts right Keq > Q

A solution in which the proportion of solute to solvent is large is said to be

concentrated

The value of Keq is ___________ at a given temperature

constant

What is a solvent?

the substance in which the solute dissolves

Nitrogen dioxide gas can be formed by the endothermic reaction shown below. Which of the following changes to the equilibrium would NOT increase the formation of NO2? A. An increase in temperature B. A decrease in the volume C. Adding additional N2O4 D. Removing NO2 as it is formed

B

The following equilibrium exists in a closed container: N2(g) + O2(g) 2 NO(g) ΔH = +181 kJ/mol Which of the following perturbations would favor the formation of NO(g)? A. Increasing the pressure B. Decreasing the pressure C. Decreasing the temperature D. Increasing the temperature

D

When the reaction 2A + B <—> C reaches equilibrium, [A] = .1M and [C] = .2M. If the value of Keq for this reaction is 8, what is [B] at equilibrium? A. .1M B. .2M C. .4M D. .5M

D

Which of the following acids can be added to an unknown salt solution and NOT cause precipitation? A. HCl B. HI C. H2SO4 D. HNO3

D

What is a solution?

A homogeneous mixture of two or more substances

N2(g) + 3 H2(g) 2 NH3(g), ΔH = -22 kcal/mol What is the effect of decreasing the volume of the system? A. An increase in the reverse reaction due to increased pressure B. An increase in the forward reaction due to increased pressure C. An increase in the reverse reaction due to decreased pressure D. An increase in the forward reaction due to decreased pressure

B

What are kinetic products?

Higher in free energy, form at lower temperatures, and form fast

What is Raoult's Law?

Ideal solution behavior is observed when solute-solute, solvent-solvent, and solute-solvent interactions are all very similar. example: benzene and toluene

What effect does raising the temperature of an endothermic reaction do?

If a reaction is endothermic, delta H > 0, think of the temperature as a reactant. Adding a reactant shifts the reaction to the right

dilution equation

M1V1=M2V2

What salts are always soluble?

Nh4+, group I cations, nitrates, and acetates

Consider this reaction: Mg(OH)2(s) <--> Mg2+ (aq) + 2 OH- (aq) What would happen if we now added some sodium hydroxide, NaOH to this solution.

Since NaOH is very soluble in water, it will dissociate completely. The addition of NaOH has caused the amount of hydroxide ion - the common ion - in the solution to increase. This disturbs the equilibrium of Mg(OH)2 since the concentration of a product that equilibrium is increased.

What does it mean when Qsp = Ksp

Solution is saturated

What is an ideal solution?

When the new interactions is equal to the overall strength of the original.

Are halides water soluble?

Yes, except F- Exceptions are Ag+, Pb2+, and Hg2+

Are sulfate ions soluble

Yes, except with Ca2+, Ba2+, and Pb2+

A solid in a solid is called what?

an alloy

Changing the volume stress equilibrium OBLY if the number of moles of gas ___________ in the reaction

changes

If temperature changes, then the Keq _________

changes

A salts solubility will _________ if added to a solution containing something that removes a common ion.

decrease

When delta G is positive, the process is nonspontaneous, and the solute is said to be __________

insoluble

What effect do catalysts have on equilibrium

no effect

If more solute is added to a saturated solution, it will not dissolve but rather remain in the solid form, __________ to the bottom of the container

precipitating

For the equilibrium constant (Keq), what goes in the numerator?

products

What are colligative properties?

properties that depend on the # of solute particles, but not on the type

Delta G > 0, Keq < 1

reactants are favored at equilibrium

What does Keq < 1 mean?

reactants favored

What does Q > Keq mean?

reactants favored Reverse rate of reaction is increases Delta G > 0

What is the ion product?

reaction quotient for a solubility reaction, written as Qsp or IP

What is not included in the equilibrium constant?

solids and liquids

For the equilibrium constant, what becomes the exponents?

stoichiometric coefficients

The value of the equilibrium constant for the reaction: 2 COF2 (g) <--> CO2 (g) + CF4 (g) is Keq = 2. If a 1 L reaction container holds one mole each of CO2 and CF4 and .5 mole of COF2, then: A. The reaction is at equilibrium B. The forward reaction will be favored C. The reverse reaction will be favored D. No prediction can be made without knowing the pressure of the container

C;

If 3 moles of N2O4 is places in a .5L container and allowed to react equilibrium according to the following reaction: N2O4 (g) <—> 2 NO2 (g), what will the equilibrium concentration of NO2, given Keq for the reaction is 6 x 10^-6?

6 x 10^-3 M

In a sealed 1 L container, 1 mole of nitrogen gas reacts with 3 moles of hydrogen gas to form 0.05 moles of NH3 at equilibrium. Which of the following is closest to the Kc of the reaction? A. 0.0001 B. 0.001 C. 0.01 D. 0.1

A

The term chemical equilibrium applies to a system: A. Where the forward and reverse reaction have stopped B. Whose rate law is of zero order C. Where individual molecules are still reacting, but there is no net change in the system D. In which ll components are in the same phase

C

The value of the solubility product for copper(I) chloride is Ksp = 1.2 x 10^-6. Under normal conditions, the maximum concentration of an aqueous CuCl solution should be: A. Less than 10^-6 M B. Greater than 10^-6 and less than 10^-4 M C. Greater than 10^-4 and less than 10^-2 M D. Greater than 10^-2M and less than 10^-1 M

C

Which of the following would have no effect on an equilibrium in which one mole of gas is decomposed into two moles of gas? A. Reduction of the volume of the container B. Addition of either one of the products C. Addition of an inert gas at constant volume D. Addition of the reactant

C

What does Keq > 1 mean?

products favored

AgCl(s) <—> Ag+ + Cl- Ksp = 1.6 x 10^-10 Ag+ (aq) + 2 NH3 (aq) <—> [Ag(NH3)2]+ (aq) Keq = 1.5 x 10^7 Overall: AgCl (s) + 2 NH3 <—> [Ag(NH3)2]+ (aq) + Cl- (aq) K overall = 10^-3 What effect did addition of a complex ion have on this reaction

Increased solubility

What effect does adding an inert gas at constant pressure do?

Increases volume

What happens when solvation is exothermic?

New interactions are stronger than the original. This is favored at low temperatures

What happens when solvation is endothermic?

New interactions are weaker than the origina ones. This is favored at high temperatures.

Are carbonates, phosphates and sulfides water soluble?

No Exceptions are alkali metals and ammonium

Are metal oxides soluble?

No, they are insoluble They are soluble if formed with Ammonia, group I metals, Ca, Sr or Ba

Solutes that dissolve minimally (molar solubility under .1M) are called

sparingly soluble salts

Raising the temperature favors _________ reactions

endothermic

What is boiling point elevation?

the difference in temperature between the boiling point of a solution and the boiling point of the pure solvent

What is freezing point depression?

the difference in temperature between the freezing point of a solution and the freezing point of the pure solvent

What is solubility of a substance?

the maximum amount of that substance that can be dissolved in a particular solvent at a given temperature

What is a solute?

the substance that is dissolved

400 g AlCl3 is dissolved in 1.5 L of water at room temperature (Kb .512 K kg / mol). How much does the boiling point increase after adding the aluminum chloride.

4K

In general, solutes are considered soluble if they have a molar solubility above _________ in solution

.1M

What is the change in vapor pressure when 180 grams of glyceraldehyde (C3H6O3) are added to .18L of water at 100C?

180 g x 1 mol /90g = 2 mole .18L; 180 g x 1 mol/18g = 10 mole 10 mole H2O/12 moles total = .83 PA = (.83)(1atm) Change in vapor pressure = .17 atm

400 G OF AlCl3 is dissolved in 1.5 L of water at room temperature. (Kf = 1.86 K kg /mol). What is the new freezing point of this solution?

257K

The solubility for lithium phosphate, Li3PO4, is Ksp = 2.7 x 10^-9. How many moles of this salt would be required to form a saturated, 1 L aqueous solution.

3.2 x 10^-3

The Hager process takes place in a container of fixed volume and is at equilibrium: N2(g) + 3 H2 (g) <—> NH3 (g) + heat. The amounts of the gases present are measured and recorded. Some additional N2 (g) is then injected into the container, and the system is allowed to return to equilibrium. When it does: A. The amount of H2 will be smaller than before, and the amounts of N2 and NH3 will be greater than before. B. The amount of N2 will be smaller than before, and the amounts of H2 and NH3 will be greater than before. C. The amount of NH3 will be smaller than before, and the amounts of N2 and H2 will be greater than before. D. The amounts of all three gases will be the same as before.

A

Which of the following statements best describes the effect of lowering the temperature of the following reaction? A + B <—> C + D + heat A. [C] and [D] would increase. B. [A] and [B] would increase. C. ΔH would increase. D. ΔH would decrease.

A

arbonated beverages are produced by dissolving carbon dioxide in water to produce carbonic acid: CO2 (g) + H2O (l) <—> H2CO3 (aq) When a bottle containing carbonated water is opened, the taste of the beverage gradually changes as the carbonation is lost. Which of the following statements best explains this phenomenon? A. The change in pressure and volume causes the reaction to shift to the left, thereby decreasing the amount of aqueous carbonic acid. B. The change in pressure and volume causes the reaction to shift to the right, thereby decreasing the amount of gaseous carbon dioxide. C. Carbonic acid reacts with environmental oxygen and nitrogen. D. Carbon dioxide reacts with environmental oxygen and nitrogen.

A

What is a complex ion?

A metal ion surrounded by coordinately bonded ligands.

In a chemical equilibrium: A. the forward and reverse reaction have stopped each other. B. the rate constants of the forward and reverse reactions are equal. C. the products and reactants are static. D. the concentrations of the products and reactions are static.

D

A high pressure gaseous synthesis of hydrazine (H4N2) at moderate temperatures is governed by the following equilibrium: 2 NH3 H4N2 + H2, Keq = 10-2 If 2 mol of each of the three species is added to the flask and the progression of the reaction is monitored, which of the following will be observed? A. An increase in the concentration of NH3, and a decrease in the concentrations of H4N2and H2 B. An increase in the concentration of NH3, and an increase in the concentrations of H4N2and H2 C. An increase in the concentration of H4N2, and a decrease in the concentrations of NH3 and H2 D. A decrease in the concentration of NH3, and an increase in the concentrations of H4N2 and H2

A; A high pressure gaseous synthesis of hydrazine (H4N2) at moderate temperatures is governed by the following equilibrium: 2 NH3 H4N2 + H2, Keq = 10-2 If 2 mol of each of the three species is added to the flask and the progression of the reaction is monitored, an increase in the concentration of NH3, and a decrease in the concentrations of H4N2 and H2 will be observed as the reaction proceeds to equilibrium. The reaction quotient (Q = [H4N2][H2]/[NH3]2) for the reaction in question at the initial conditions is equal to 1. As this value is greater than Keq, the reaction must move to the left to attain equilibrium. Answer choices indicating that both sides of the reaction move in the same direction, can be easily eliminated, as can choices in which species on the same side of the equilibrium equation move in opposite directions.

If a reaction has a ΔH° < 0 and a ΔS° > 0, the Keq is A. greater than 1, and the products are favored. B. greater than 1, and the reactants are favored. C. less than 1, and the products are favored. D. less than 1, and the reactants are favored.

A; A negative ΔH° and positive ΔS° will always give a negative ΔG°. In the context of equilibrium, this means that the products are favored (eliminate choices B and D). This corresponds to a Keq greater than 1 since K is a ratio of [products]/[reactants], making choice A the correct answer.

Consider the reaction . At equilibrium, a 10 L vessel contains 1.5 moles of HI, 0.1 moles of I2 and 0.3 moles of H2. Which direction will the reaction proceed if 2 moles of HI, and 0.5 moles of both I2 and H2 are mixed in a separate 10 L vessel? A. The reaction will proceed forward. B. The mixture will be at equilibrium. C. This cannot be determined with the given information. D. The reaction will proceed in reverse.

A; Consider the reaction. At equilibrium, a 10 L vessel contains 1.5 moles of HI, 0.1 moles of I2 and 0.3 moles of H2. The reaction will proceed forward if 2 moles of HI, and 0.5 moles of both I2 and H2 are mixed in a separate 10 L vessel. All of the information needed to answer this question is given, so the answer choice "this cannot be determined with the given information" can be eliminated. First, Keq can be determined with the equilibrium moles of each compound despite not knowing the total pressure of the vessel. The derivation is shown here for clarity but could be skipped as the expression reduces down to the ratio of moles products to moles reactants at equilibrium raised to the power of their coefficients in the balanced equation: Next, calculate the reaction quotient, Q, for the second vessel in a similar manner: Since Q < K, the forward reaction is favored.

A chemist seals a rigid reaction vessel containing a gaseous reaction at equilibrium and begins pumping in helium gas. She fails to see a change in the relative quantity of reactants and products in the system of study. Which of the following best explains these observations? A. Total pressure has increased with no change in the reaction quotient. B. Total pressure has increased with compensatory changes in Q and Keq. C. Total pressure has decreased with no change in the reaction quotient. D. Total pressure has decreased with compensatory changes in Q and Keq.

A; Sealing a rigid container and adding a gas to the vessel will increase total pressure (choices C and D are incorrect). Addition of an inert gas also results in a corresponding decrease in the mole fraction for each gas in the mixture, resulting in no change in partial pressures and therefore no change in Q(choice A is correct and choice B is incorrect). Note that changing reactant or product concentrations cannot change Keq, only a change in temperature changes the value of K.

Addition of reactant to a previously equilibrated system will result in which of the following? A. K > Q and the forward reaction predominates B. K > Q and the reverse reaction predominates C. K < Q and the forward reaction predominates D. K < Q and the reverse reaction predominates

A; Since a K or Q expression is a ratio of [products]/[reactants], addition of a reactant will decrease the reaction quotient and have no impact on the equilibrium constant which depends only on temperature, thus K > Q (choices C and D are incorrect). When K > Q, the reaction proceeds forward in order to use reactants, make products, and reestablish equilibrium where Q = K(choice B is incorrect and A is correct).

Equal volumes of equimolar solutions of Pb(CH3CO2)2 and HI are mixed, forming a yellow precipitate. Which of the following represents the reaction described? A. Pb2+(aq) + 2 I-(aq) → PbI2(s) B. H+(aq) + CH3CO2-(aq) → CH3CO2H (s) C. 2 I-(aq) → I2(s) D. CH3CO2-(aq) + I-(aq) → CH3I (s) + CO2(g)

A; Since both starting compounds are electrolytes and dissociate in solution, the cation of one compound will pair with the anion of the other compound in a double displacement reaction, yielding both of the products suggested in choices A and B. Choice A is the better option, however, because CH3CO2H (acetic acid) is a liquid, not a solid. Most Pb compounds are insoluble and are likely precipitates in such reactions. Choice C can be eliminated since two negatively charged iodide ions cannot pair up to make a neutral I2 molecule unless electrons are removed (an oxidation), which is not indicated here. Choice D can also be eliminated for similar reasons. Two anions cannot form two neutral compounds unless electrons are removed from the system. In addition, methyl iodide should be expected to be a liquid as it has a relatively low molar mass and a low polarity, giving it weak intermolecular forces.

The [Pb2+] of a solution is 1.25 × 10-3 M. Calculate the [SO42-] that must be exceeded before PbSO4can precipitate. (The solubility product of PbSO4 at 25°C is 1.6 × 10-8.) A. 1.3 × 10-5 M B. 1.3 × 10-4 M C. 1.6 × 10-8 M D. 6.4 × 10-6 M

A; The [Pb2+] of a solution is 1.25 × 10-3 M. The [SO42-] that must be exceeded before PbSO4 can precipitate is 1.3 × 10-5 M. (The solubility product of PbSO4 at 25°C is 1.6 × 10-8.) The concentrations of the dissolved ions must exceed the Ksp value for precipitate to form. Given the dissolution of PbSO4, PbSO4(s) Pb2+(aq) + SO42-(aq) we have Ksp = [Pb2+][SO42-]. Therefore, the minimum concentration of SO42- needed to form precipitate is [SO42-] = Ksp/[Pb2+] = (1.6 × 10-8)/(1.25 × 10-3) = 1.3 × 10-5 M.

The reaction SbCl5 Cl2(g) + SbCl3 has a Keq of 3.2 × 10-6. Yet despite the small Keq when SbCl5 is dissolved and stirred in organic solvents for extended periods of time, unexpectedly high levels of solvated SbCl3 are measured in solution. Which of the following best explains this phenomenon? A. Cl2(g) escapes from solution, driving the equilibrium toward SbCl3. B. The forward reaction has a large negative entropy, which drives the reaction to the right. C. When large amounts of SbCl5 are added to solution, Keq for the reaction gets larger. D. SbCl3 is an unstable species in organic solvents.

A; The reaction SbCl5 Cl2(g) + SbCl3 has a Keq of 3.2 × 10-6. When SbCl5 is dissolved and stirred in organic solvents for extended periods of time, unexpectedly high levels of solvated SbCl3 are measured in solution because Cl2(g) escapes from solution, driving the equilibrium toward SbCl3. The phenomenon above is a description of Le Chatelier's Principle. The escape of non-solvated gas from solution would force the accumulation of SbCl3 in order to maintain Keq. As Le Chatelier's Principle would predict, if Cl2(g) is removed from equilibrium, the reaction will shift toward the right side of the equation. The value of Keq is unaffected by the quantities of reactants in the mixture and only changes when the temperature does. The forward reaction produces a gas, which would indicate a positive entropy.

A high pressure gaseous synthesis of hydrazine (H4N2) is governed by the following equilibrium: 2 NH3 H4N2 + H2, Keq = 10-7 If a 1 L system is charged with 10 mol of NH3, how much hydrazine will be present at equilibrium? A. 0.003 mol B. 0.03 mol C. 0.01 mol D. 0.001 mol

A; When a 1 L system is charged with 10 mol of NH3, 0.003 mol of H4N2 will be present at equilibrium. At equilibrium we can say that K = [H4N2][H2]/[NH3]2 = 10-7. Allowing [H4N2] = [H2] = x while [NH3] = 10 - 2x, we get x2/(10 - 2x)2 = 10-7. As Keq is small we can safely disregard 2x in the denominator, giving x2 = 10-5, or x = 10-2.5. This value is between 10-2 and 10-3, meaning 0.003 is the only possible answer.

Acetic acid dissociates in solution according to the following equation: CH3COOH <—> CH3COO- + H+ If sodium acetate is added to a solution of acetic acid in excess water, which of the following effects would be observed in the solution? A. Decreased pH B. Increased pH C. Decreased pKeq (pKa) D. Increased pKeq (pKa)

B

The following reaction is allowed to reach equilibrium: Cl2O(g) + 2 OH-(aq) 2 OCl-(aq) + H2O(l) What will be the effect of then doubling the hydroxide concentration? A. The reaction quotient will be four times the equilibrium constant, favoring the reverse reaction. B. The reaction quotient will be one-fourth the equilibrium constant, favoring the forward reaction. C. The reaction quotient will be one-half the equilibrium constant, favoring the forward reaction. D. The reaction quotient will be twice the equilibrium constant, favoring the forward reaction.

B

Which of the following observations is inconsistent with the solubility rules? A. More sugar dissolves in a pot of hot water than a pot of cold water B. Boiler scales are caused by the precipitation of CaCO3 inside plumbing when hot water heaters heat up cold well water. C. After breathing compressed air at depth, scuba divers that ascend to the surface too quickly risk having air bubbles in their body. D. Boiling the water before making ice cubes out of it results in clear ice cubes that have no trapped air bubbles.

B

Which of the following is necessarily true for any reaction at equilibrium? A. TΔS < 0 B. TΔS > 0 C. ΔG˚= 0 D. ΔH = TΔS

D

A sample of solid Mg(OH)2 is added to water and reaches equilibrium with its dissociated ions. Addition of the strong base NaOH would most notably increase the concentration of: A. Mg2+ . B. undissociated magnesium hydroxide. C. undissociated sodium hydroxide. D. H3O+.

B; A sample of the salt Mg(OH)2 is dissolved in water and reaches equilibrium with its dissociated ions. Addition of the strong base NaOH would most notably increase the concentration of undissociated magnesium hydroxide. The addition of hydroxide (from NaOH) would decrease the solubility of magnesium hydroxide due to the common ion effect. Therefore, the amount of undissociated Mg(OH)2 would increase.

A researcher wishes to prepare a saturated solution of a lead compound that contains the greatest concentration of lead(II) ions. Of the following, which should she use? A. Pb(OH)2 (Ksp = 2.8 x 10^-16) B. PbCl2 (Ksp = 1.7 x 10^-5) C. PbI2 (Ksp = 8.7 x 10^-9) D. PbBr2 (Ksp = 6.3 x 10^-6)

B; B is the largest value

Which of the following is true of equilibrium reactions? I. An increase in k1 results in a decrease in k-1. II. As the concentration of products increases, the concentrations of reactants decreases. III. The equilibrium constant is altered by changes in temperature. A. I only B. II and III only C. I and III only D. I, II, and III

B; I is wrong because the addition of a catalyst could increase the rate constants of both the forward and reverse II is true because for products to come into existence - reactants must be used up. III. True statement

If Keq for a given reaction is large in standard state conditions, which of the following is necessarily true about the thermodynamic parameters of the reaction? A. ΔG is negative B. ΔG˚ is negative C. ΔH is negative D. ΔH˚ is negative

B; If Keq for a given reaction is large in standard state conditions, we know ΔGo is negative. This can be determined from the relationship ΔG° = -RTlnKeq. The value of ΔH° may be positive or negative, depending on the sign of the standard state entropy change. The non-standard state parameters can be ruled out, as we have no information which could allow us to predict their sign

If the solubility of AgCl in water is 1.3 × 10-4 mol/L, calculate the solubility product of AgCl. A. 6.5 × 10-5 B. 1.7 × 10-8 C. 1 × 10-2 D. 1.3 × 10-4

B; If the solubility of AgCl in water is 1.3 × 10-4 mol/L, the solubility product of AgCl is 1.7 × 10-8. The equilibrium dissociation of AgCl is given by the equation AgCl(s) Ag+(aq) + Cl-(aq), so Ksp = [Ag+][Cl-]. If the concentration of dissolved AgCl is 1.3 × 10-4 M, then [Ag+] = [Cl-] = 1.3 × 10-4 M also. Therefore, Ksp = (1.3 × 10-4)2 = 1.7 × 10-8.

The ΔG° of a reaction increases following an increase in temperature. What impact would this have on the equilibrium constant? A. It increases. B. It decreases. C. It does not change. D. Inadequate information is provided to determine the outcome.

B; If the ΔG° of a reaction increases with increasing temperature, this will cause a decrease in the equilibrium constant (choice B is correct). Qualitatively, as ΔG° increases, the reaction becomes less spontaneous and favors the reactants to a greater degree. With an increase in reactants at equilibrium, the K decreases since K is a ratio of [products]/[reactants]. Quantitatively, ΔG° = -RT ln K, thus as ΔG° increases, K must decrease.

Which of the following substances, when added to a saturated solution containing both aqueous and solid silver chloride, will cause dissolution of the silver chloride solid through complex ion formation with Ag? A. Aqueous silver nitrate B. Aqueous potassium cyanide C. Aqueous sodium chloride D. Aqueous sodium acetate

B; In order to solubilize the solid silver chloride, the aqueous ions must be consumed (Le Châtelier's Principle) causing the equilibrium to shift and dissolve more solid silver chloride. Alternatively, the silver chloride must be converted to a soluble substance, such as a complex ion. Adding neutral salts of silver or chloride is the common ion effect and will actually reduce the solubility of silver chloride, causing more precipitation, not dissolution (eliminate choices A and C). Aqueous potassium cyanide will cause the formation of the complex ion dicyanoargenate, Ag(CN)2- (aq), resulting in the consumption (dissolution) of the solid silver chloride. AgCl(s) + 2 CN-(aq) ? Ag(CN)2-(aq) + Cl-(aq). The addition of sodium acetate will have no effect, since both sodium and acetate salts are known to be completely dissociated in solution (eliminate choice D).

Which of the following changes to an equilibrated system is most likely to change the proportion of reactants and products at equilibrium? A. Increasing activation energy B. Increasing product stability C. Increasing reactant concentration D. Increasing reaction rate

B; Increasing product stability will increase the relative proportion of products at equilibrium (choice B is correct). Changes in reaction rate (and other kinetic changes) are not likely to impact equilibrium (or other thermodynamic properties - choices A and D are wrong). Increasing reactant concentration will temporarily decrease the reaction quotient, Q, but once equilibrium has been re-established, the same proportions of reactants and products will exist (choice C is wrong).

The Ksp of NaCl in water is 35.9 at 25C. If 500 mL of 12M NaOH (aq) and 500 mL of 12M HCl (aq) solution both at 25C are combined, what would best describe the resulting solution? A. A small amount of NaCl (s) would precipitate B. There will be a 6M aqueous solution C. Enthalpy and entropy would increase D. The resulting solution would be slightly basic

B; Neutralization reactions are exothermic and form salt and water. The starting 500 mL solutions contain 6 moles each of NaOH and HCl. The final solution will be 1 L of 6M NaCl (Aq). The temp increases so more can dissolve, eliminating A. Choice C is eliminated because enthalpy decreases when heat is given off in an exothermic reaction. Choice D is eliminated because NaCl is a neutral salt.

Which of the following reactions favors reactants to the greatest degree at equilibrium? A. H2(g) + I2(g) ? 2 HI(g) Keq = 2.8 x 10^1 B. HC2H3O2(aq) ? C2H3O2-(aq) + H+(aq) Keq = 1.79 x 10^-5 C. N2O4(g) ? 2 NO2(g) Keq = 8.7 x 10^-1 D. 2 NH3(g) ? N2(g) + 3 H2(g) Keq = 2.3 x 10^1

B; The equilibrium constant is a ratio of products to reactants established at equilibrium. As we are looking for the reaction that favors the reactants to the greatest degree, we are looking for the smallest equilibrium constant (choice B is correct).

Some high-Pb commercial bronzes consist of 40% Cu, 34% Zn and 26% Pb (wt. %). In such a material, what is the mole fraction of Pb? A. 0.05 B. 0.10 C. 0.25 D. 0.37

B; The mole fraction of Pb in bronze alloy consisting of 40 wt.% Cu, 34 wt.% Zn, and 26 wt.% Pb is 0.10. Assuming 100 g of bronze, 40 g will be Cu (63.5 g/mol), 34 g will be Zn (65 g/mol) and 26 g will be Pb (209 g/mol).40 g / (63.5 g/mol) = ~0.6 mol Cu34 g / (65 g/mol) = ~0.5 mol Zn26 g / (209 g/mol) = ~0.12 mol PbTherefore, there are ~0.12 mol of Pb in a total of ~1.2 mol of bronze. Since 0.12 / 1.2 = 0.1, answer choice B is the best.

A reaction is found to stop just before all reactants are converted to products. Which of the following could be true about this reaction? A. The reaction is irreversible, and the forward rate is greater than the reverse rate. B. The reaction is irreversible, and the reverse rate is too large for products to form. C. The reaction is reversible, and the forward rate is equal to the reverse rate. D. The reaction is reversible, and the reverse rate is greater than the forward rate.

C

A saturated, aqueous solution of KBr is heated at its boiling point for five minutes, at which point a white solid appears in the flask. Which of the following explains these observations? A. KBr is less soluble at high temperatures and precipitates out of the solution upon boiling. B. KBr is unstable at the boiling point of water and decomposes into an insoluble product. C. KBr precipitates as the solution becomes more concentrated due to the evaporation of water. D. KBr can no longer be solvated as the average kinetic energy of the water molecules increases.

C

If the reaction 2 NO (g) + O2 (g) <—> 2 NO2 (g); Delta H = (-) is at equilibrium, which of the following changes would cause the formation of additional NO2(g) A. Increasing the temperature B. Adding a catalyst C. Reducing the volume of the reaction container D. Removing some NO (g)

C

SO2(g) + 1/2 O2(g)SO3(g) What is the equilibrium expression for the reaction above? A. Keq = [SO2] [O2]1/2/[SO3] B. Keq = [SO3]2/[SO2]2 [O2] C. Keq = [SO3]/[SO2] [O2] D. Keq = [SO3]/[SO2] [O2]1/2

D

A researcher places a sample of radiolabeled AgI into a saturated solution of non-radiolabeled AgI and several hours later inadvertently spills some of the liquid on a nearby countertop. Is the researcher in danger while cleaning this spill? A. No, the radioactive solid is insoluble so the spilled liquid contained only non-radiolabeled ions. B. No, at equilibrium, the reaction would thermodynamically drive any radioactive iodide into the solid. C. Yes, a portion of the radioactive iodide in the solid would have been replaced by the non-radiolabeled isotope. D. Yes, the iodide initially present in the solid would all enter solution and diffuse equally throughout the liquid.

C; Chemical equilibria are dynamic, so while there is no net flux between reactants and products (the solid and aqueous forms of the solute), this does not preclude the interchanging of individual ions of the two iodide isotopes between these forms (choice C is correct, choices A and B are wrong). Diffusion would play a role in dispersing aqueous iodide, but given we are placing more solid in a saturated solution, some of the radioactive iodide will remain in the solid (choice D is wrong).

Shvo's Catalyst is an attractive promoter of gas-phase hydrogenation and dehydrogenation in the cyclohexene/cyclohexane system H2 + cyclohexene --> cyclopentane If a microporous cylinder designed to allow slow effusion is charged with the three species, after an initial rapid equilibration, what changes in the relative amounts of the species, if any, will be observed? A. The relative concentration of cyclohexane will increase and the relative concentration of cyclohexene will decrease. B. Shvo's catalyst will enhance the forward rate, pushing the equilibrium to the right. C. The relative concentration of cyclohexene will increase and the relative concentration of cyclohexane will decrease. D. The equilibrated mixture shows no changes through time.

C; Effusion of the three gaseous species from the cylinder does not occur at the same rate. The rate of effusion is governed by average molecular velocity, and hence molecular weight. Since H2 is by far the lightest, if will effuse out of the cylinder much faster than the other species, pushing the equilibrium to the left, and increasing the relative concentration of cyclohexene. Catalysts do not affect equilibrium, so that answer can be safely eliminated.

Compound A has a Ka (equilibrium constant of acid dissociation) of approximately 10^-4. Which of the following compounds is most likely to react with a solution of compound A? A. HNO3 B. NO2 C. NH3 D. N2O5

C; Ka of less than 10^-7 = acid. Acid and bases react. Answer is C.

Which of the following answer choices accurately describes the thermodynamics of the following reaction? H2(g) + I2 (g) <--> 2HI (Keq = 0.5 at 25°C) A. Reactants are favored at equilibrium and ΔG° will be less than zero. B. Products are favored at equilibrium and ΔG° will be less than zero. C. Reactants are favored at equilibrium and ΔG° will be greater than zero. D. Products are favored at equilibrium and ΔG° will be greater than zero.

C; Reactants are favored at equilibrium and ΔG° will be greater than zero accurately describes the thermodynamics of the following reaction. (Keq = 0.5 at 25°C) This is a two by two question, so approach each part of the answer choices separately. Given Keq < 1, reactants are favored at equilibrium, eliminating the choices written "products are favored..." If Keq < 1, then ΔG° will be greater than zero (non-spontaneous in the forward direction) according to the equation: ΔGº = -RTlnKeq.

Na2SO4 is soluble in water. If NaCl (s) is added to the solution of Na2SO4(aq) so that the concentration doubles, then the: A. Solubility constant of Na2SO4 increases while that of NaCl decreases. B. Solubility constants Na2SO4 and NaCl both decrease C. Solubility of Na2SO4 and NaCl both decrease D. Solubility of Na2SO4 decreases while that of NaCl increases

C; Solubility constants like all equilibrium constants are dependent on temperature only, eliminating A and B. Na+ is a common ion to both systems. Increasing Na+ concentration will decrease the solubility of both salts.

I2(g) + Br2(g)2 IBr(g) What can be concluded about the reaction above if its equilibrium constant is measured to be 1.2 x 10^2? A. Twice as many products as reactants are present at equilibrium. B. The ΔG° for this reaction is positive. C. Products are more stable than reactants. D. The reaction rapidly establishes equilibrium.

C; The equilibrium constant is a ratio of products to reactants, so when K > 1, there are more products than reactants at equilibrium. At equilibrium, the side of a reaction with the greatest stability will be favored (choice C is correct). While products are heavily favored, it is to a much larger degree than twice as many products as reactants present at equilibrium (choice A is incorrect). Given the equilibrium favors the products, the ΔG° will be negative, not positive (choice B is incorrect). Since kinetics and thermodynamics are very distinct topics in chemistry, the equilibrium constant tells us nothing about the rate of a reaction and how quickly it reaches equilibrium (choice D is incorrect).

Which of the following balanced reactions most likely possesses an equilibrium constant where Keq = [HI]2/[H2]? A. H2(g) + 2 I3-(aq) <--> 2 I2(s) + 2 HI(aq) B. H2(g) + 2 I-(aq) <--> 2 HI(g) C. H2(g) + I2(s) <--> 2 HI(g) D. 1/2 H2(g) + 1/2 I2(s) <--> HI(g)

C; The equilibrium constant is dictated by the concentration of products over reactants, raised to the power of their coefficients. Both pure solids and liquids are omitted, but gases and aqueous substances are included. Thus for the equilibrium expression [HI]2/[H2], we would expect HI as a gaseous or aqueous product with a coefficient of 2 and H2 as a reactant with a coefficient of 1 (choice D is incorrect). Charge must be balanced in a chemical reaction, and any aqueous ions should appear in the equilibrium expression if appropriately part of the balanced reaction (choices A and B are incorrect). Thus the equilibrium expression Keq = [HI]2/[H2] best describes the balanced reaction H2(g) + I2(s) ? 2 HI(g) (choice C is correct).

If the following endothermic reaction is at equilibrium in a rigid reaction vessel, CH4 (g) + H2O (g) <—> CO (g) + 3 H2 (g) A. Adding Ne (g) B. Removing some H2O (g) C. Increasing the pressure D. Increasing the temperature

D

The formation constant (Kf) for the complex ion [Fe(en)3]2+ is 5.0 × 109, whereas the Kf for [Fe(ox)3]4- is 1.7 × 105 (en = 1,2 diaminoethane, ox = oxalate anion). Based on this information, which of the following statements is true? A. The higher the oxidation state on the transition metal, the larger the formation constant. B. Complexes with bidentate ligands always have higher Kf values than the corresponding monodentate complexes. C. 1,2-Diaminoethane is a stronger ligand with iron(II) than the oxalate ion. D. A reaction between oxalate ion and [Fe(en)3]2+ will form [Fe(ox)3]4- completely.

C; The formation constant (Kf) for the complex ion [Fe(en)3]2+ is 5.0 × 10^9, whereas the Kf for [Fe(ox)3]4- is 1.7 × 10^5 (en = 1,2 diaminoethane, ox = oxalate anion). Based on this information, 1,2-diaminoethane is a stronger ligand with iron(II) than the oxalate ion. Formation constants are equilibrium constants for the formation of complex ions. The larger the equilibrium constant of a reaction, the larger the ratio of products to reactants at equilibrium will be. The oxalate complex with iron(II) has a lower Kf than the diamine complex. Therefore, any competitive reaction will favor the diamine complex, so [Fe(en)3]2+ is favored to form, not [Fe(ox)3]4-. Since both complexes have iron(II) as the central metal, there isn't any information to support the relationship suggested between oxidation state and the value of the formation constant. When comparing competing ligands, the one with the larger Kf will yield the more stable complex, which is due to the strongest Lewis acid/Lewis base interactions. Therefore, the diamine must be the stronger ligand. Both of the ligands in the question are bidentate, so there is no information to use for comparison between ligand type and value of Kf.

Which of the following salts is expected to be insoluble in water? A. CsOH B. NH4NO3 C. CaCO3 D. AgClO4

C; all carbonates are insoluble A contains a group I metal, which makes the OH soluble B contains NH4 and NO3; very soluble D contains perchlorate

Which of the following illustrates a chemical system that is at equilibrium? I. Bubbles forming in solution II. A solution saturated with solute III. The ratio of products to reactants remains constant A. I only B. II only C. I and II only D. II and III only

D;

CH4(g) + 2 S2(g)CS2(g) + 2 H2S(g) Once the system shown reaches equilibrium, increasing [CH4] will result in each of the following EXCEPT: A. a decrease in the reaction quotient. B. an increase in the total quantity of H2S(g) formed at equilibrium. C. a decrease in the total quantity of S2(g) formed at equilibrium. D. an increase in the Keq for the reaction.

D; An increase in reactant concentration will decrease the reaction quotient (choice A is a true statement, so can be eliminated). With an increase in reactant concentration, an equilibrium shift to the products occurs, resulting in increased total quantities of each product being formed (choice B is true, so can be eliminated). When the equilibrium shifts to the products side, it must use up reactants, so the amount of S2 should decrease (choice C is true, so can be eliminated). Changes in reactant or product concentration do not result in a change in Keq as this value is only determined by the temperature of the system. Since temperature remains constant, the value of K does not change, making choice D the correct answer.

Once equilibrium has been established, each of the following are true EXCEPT: A. the system has reached an energy minimum. B. no net flux of reactant to product occurs. C. the rates of the forward and reverse reactions are equal. D. equal quantities of products and reactants are present.

D; At equilibrium, the quantities of reactant and product are not necessarily equal, however the proportions will be consistent (choice D is not true of a system at equilibrium and is the answer). By definition, a reaction at equilibrium will have equal rates of forward and reverse reactions, meaning no net flux of reactants or products (choices B and C are true of a system at equilibrium and can be eliminated). At equilibrium, the system has established an energy minimum, which accounts for the spontaneous progression of the reaction toward equilibrium (choice A is true of a system at equilibrium and can be eliminated).

Complex Ion Kf [Co(ox)3]4- 5.0 × 10^9 [Co(ox)3]3- 1.0 × 10^20 [Fe(ox)3]4- 1.7 × 10^5 [Fe(ox)3]3- 2.0 × 10^20 The table above lists the formation constants for some common complex ions with the oxalate ion (ox, C2O42-). Which metal ion would react most completely with 100 mL of a 1.0 M solution of potassium oxalate to form the corresponding complex ion? A. Cobalt(II) B. Iron(II) C. Cobalt(III) D. Iron(III)

D; Formation constants, Kf, are just another form of an equilibrium constant. Therefore the complex with the largest formation constant will have the most complete reaction and result in the highest concentration. The last complex in the table, [Fe(ox)3]3-, has the largest Kf, so the metal must be iron (eliminate choices A and C). Since the charge on oxalate is -2, three ligands will contribute -6, and require the metal to have a +3 charge (eliminate choice B).

The equilibrium constant for the reaction is 617 at a given temperature. In a reaction vessel, the partial pressures of H2 and I2 are each 1 atm and the partial pressure of HI is 12 atm. What is the value of the reaction quotient, Q? A. 7.0 × 10-3 B. 8.3 ×10-2 C. 12 D. 144

D; The equilibrium constant for the reaction is 617 at a given temperature. In a reaction vessel, the partial pressures of H2 and I2 are each 1 atm and the partial pressure of HI is 12 atm. The value of the reaction quotient, Q is 144. Although calculated in the same manner, Q is independent of Keq. Q can be solved using partial pressures:

The molar solubility of HgCl2 in water is 0.27 M. If 0.1 mol of NaCl is added to 1 L of a 0.27 Maqueous solution of HgCl2, what will happen? A. NaCl will not dissolve and no precipitate will form. B. NaCl will dissolve and no precipitate will form. C. NaCl will not dissolve and HgCl2 will precipitate. D. NaCl will dissolve and HgCl2 will precipitate.

D; The molar solubility of HgCl2 in water is 0.27 M. If 0.1 mol of NaCl is added to 1 L of a 0.27 Maqueous solution of HgCl2, NaCl will dissolve and HgCl2 will precipitate. The solution of HgCl2 is saturated. NaCl is very soluble in water (solubility is over 6 M at 25°C) and will be able to dissolve completely. Because of the common ion effect, as NaCl dissolves, it will decrease the solubility of HgCl2 and cause it to precipitate.

The equilibrium between methylamine bound, and unbound, to iron pentacarbonyl is found to have a constant Keq of ~30 and an activation energy of 13 kcal/mol. NH2CH3 + Fe(CO)5 (CH3NH2)Fe(CO)5 If the amine is switched to the very bulky diisopropylethylamine, the activation energy of binding is found to increase to 39 kcal/mol. With this data, approximately what is the new value of Keq? A. Keq will increase by a factor of 3 B. Keq will decrease by a factor of log 3 C. Keq will decrease by a factor of 3 D. There is no information in the question to determine the new Keq

D; With the material given in the question, there is no information in the question to determine the new Keq for the reaction with diisopropylethylamine. The question gives information on the new activation energy, which is strictly a kinetic measurement. It says nothing about the thermodynamics of the system, so Keq with diisopropylethylamine is unknown.

What does Keq > Q mean?

Forward reaction has not yet reaches equilibrium Greater concentration of reactants Delta G < 0

What effect does lowering the temperature of an exothermic reaction do?

If a reaction is exothermic, think of heat as a product. Decreasing a product shifts the reaction to the right

What effect does lowering the temperature of an endothermic reaction do?

If the reaction is endothermic, delta H > 0, think of temperature as a reactant. Removing a reactant shifts the reaction to the left.

What effect does raising the temperature of an exothermic reaction do?

If the reaction is endothermic, think of heat as a product. Increasing a product shifts the reaction to the left.

What is the mass-action ratio?

It states that the rate of a reaction is proportional to the product of the concentrations of the participating molecules

What is the equilibrium constant?

K or Keq, describes the position of equilibrium

What is the expression for the equilibrium constant for the following reaction? 3 H2 (g) + N2 (g) <—> 2 NH3 (g)

Keq = [NH3]^2 / [H2]^3[N2]

The molar solubility of Fe(OH)3 in aqueous solution was determined to be 4 x 10^-10 mol/L. What is the value of the Ksp at the same temperature and pressure?

Ksp = 7.2 x 10^-37

What is the tsp of this reaction Mg(OH)2 (s) <--> Mg2 (aq) + + 2 OH- (aq)

Ksp = [Mg2+][OH-]^2

What are thermodynamic products?

Lower in free energy, more stable, proceed more slowly

What does it mean when Ksp > Qsp

More salt can be dissolved

Raoult's Law Equation

Pa=XaPa Pa = vapor pressure of solvent A XA = mole fraction of solvent A PA o = vapor pressure ol solvent A in its pure state

Delta G = 0 and Keq = 1

Products and reactants present in equal amounts

Keq >1, delta G < 0

Products are favored

H2O (l) + CO2 (g) <—> H2CO3 (aq) <—> H+ (aq) + HCO3- (aq) What happens to the blood pH when a person hyperventilates?

Rate of CO2 expiration increases, so [CO2] goes down, causing 1 to shift to the left. This results in an increase in pH, or respiratory alkalosis

What does a Keq value of 1 tell us?

Reaction has roughly equal amounts of reactants and products

What does Keq = Q mean?

Reaction is in dynamic equilibrium

What effect does the common ion effect have on Ksp?

Remains constant

What cations are insoluble?

Silver (Ag+), lead (Pb 2+/Pb4+) and mercury (Hg 2+/Hg2+)

What happens during solvation?

Solvation involves breaking intermolecular interactions between solute molecules and between solvent molecules and forming new intermolecular interactions between solute and solvent molecules.

What effect does the addition of complex ions have on solubility?

Substantially alters it

What are the concentrations of each of the ions in a saturated solution of CuBr, given that the Ksp of CuBr is 6.27 x 10^-9 at 25C. If 3 grams of CuBr are dissolved in water to make 1L of solution at 25C, would the solution be saturated, unsaturated, or supersaturated?

Supersaturated

What is the difference between Keq and Q?

The concentrations in the expression Q do NOT have to be the concentrations at equilibrium

What is dynamic equilibrium?

The forward and backward reactions are both happening at the same time and at the same rate, and the concentrations of reactants and products have reached a balance and won't change

What is static equilibrium?

The forward and reverse reaction has stopped

What is solvation?

The process of surrounding solute particles with solvent particles to form a solution

Take this reaction: C(s) + H2O (l) <--> CO (g) + H2 (g). What effect does increasing pressure do?

Volume decreases, shifts to side with fewer moles of GAS. Reaction shifts left; Q > Keq

Take this reaction: C(s) + H2O (l) <--> CO (g) + H2 (g). What effect does decreasing pressure do?

Volume increases, shifts the reaction to the side with more moles of GAS. In this reaction, it shifts to the right; Keq > Q

What is Le Chatelier's principle?

When a reaction at equilibrium is changed, it will seek to counteract that change

When a solution has water as the solvent, it is called an _________ solution

aqueous

What effect does the common ion effect have on molar solubility

decreases it

A solution in which the proportion of solute to solvent is small is said to be

dilute

Relationship between freezing point depression and vapor pressure

direct

The process of dissolving is known as

dissolution

Each reaction will tends toward equilibrium, and for a given temperature, will have an _________ _________

equilibrium constant

Normality equation

equivalents/L

Lowering the temperature favors _________ reactions

exothermic

Comples ions are also known as

ligands or lewis bases

When the maximum amount of solute has been added, the dissolved solute is in equilibrium with its dissolved state, and we say that the solution is ____________

saturated

When you know the Ksp for a solid, you can determine the salt's molar _________, or the number of moles of salt that will saturate a liter of water

solubility

When delta G is negative, the process of solubility is spontaneous and the solute is said to be _________

soluble

What is chemical equilibrium?

when the forward and reverse reaction rates are equal

Relationship between delta G and Q equation

ΔG = ΔG(degree) + RT ln Q

Relationship between delta G and Keq equation

ΔG(degree) = -RT ln Keq

boiling point elevation equation

ΔTb=iKbm I = van't hoff Kb = proportionality constant m = molality

freezing point depression equation

ΔTf = iKfm