CHEM 112 ICE TABLE SB ASSIGNMENT
If the temperature of a system at equilibrium is increased the system will shift to use up the excess heat, favoring the _____ reaction. A decrease in temperature causes more heat to be produced, favoring the _____ reaction.
endothermic, exothermic
Which of the following options correctly describe a solution with a pH = 8.00? Select all that apply.
[OH-] > [H3O+] The solution is basic.
Without using a calculator, select the pH below of a solution whose [H3O+] is 2.7 × 10^−8M.
7.57 (Since the value of [H3O+] is between 10^-7 and 10^-8, the pH of the solution will be between 7 and 8
Which of the following statements correctly describe how the addition of a catalyst will affect an equilibrium reaction? Select all that apply.Which of the following statements correctly describe how the addition of a catalyst will affect an equilibrium reaction? Select all that apply.
A catalyst does not change the value of K. A system will reach equilibrium more quickly in the presence of a catalyst.
If a system at equilibrium is disturbed by a change in concentration, the system will shift to _____ a substance that is added and to _____ a substance that has been removed.
consume; produce
Neutral solution
pH = 7.00
A Bronsted-Lowry acid is a proton _____ and must therefore contain at least one ionizable _____ atom in its formula.
donor; hydrogen
Without using a calculator, select the pH below of a solution whose [H3O+] is 1.8 × 10^−5 M.
4.74
The pH scale is a logarithmic scale, meaning that a solution with a pH of 1.00 has a concentration of hydronium (H3O+) _____ times _____ than a solution with a pH of 3.00.
100; greater
Which of the following changes will cause the equilibrium shown to shift toward the products? Select all that apply. Fe3O4(s) + 4H2(g) ⇄ 3Fe(s) + 4H2O(g)
Add H2(g) without changing the volume. Remove H2O(g) from the reaction vessel
Which of the following is correct regarding catalysts and equilibrium?
Adding a catalyst to a reaction causes the reaction to reach equilibrium sooner.
Which of the following will change the total pressure in a reaction involving only gases at equilbrium?
Adding an inert gas Adding or removing a reactant or product Changing the volume of the container
A compound that can act as either a Bronsted acid or a Bronsted base is said to be _____
Amphoteric
Which of the following statements correctly describe the relationship between the species in the reaction shown? Select all that apply.
B and D are a conjugate acid-base pair. HSO3- is the conjugate acid of SO32-. The base in the forward reaction is CH3NH2.
Select all the compounds in the following list that are strong bases.
Ba(OH)2 NaOH RbOH
Which of the following correctly reflect ways in which a chemical equilibrium can be stressed? Select all that apply.
Changing the volume of the reaction container for a reaction involving gases Changing the concentrations of reactants or products Changing the temperature of the system
KC = 23 = (2x)2/(0.15−x)(0.18−x)
Choice, When the equilibrium constant is large, x may be significant compared to 0.15 or 0.18 and can't be neglected. Use the quadratic formula to solve for x. When the equilibrium constant is large, x may be significant compared to 0.15 or 0.18 and can't be neglected. Use the quadratic formula to solve for x.
Qc
Choice, expresses a particular ratio of product and reactant concentrations for a chemical system at any time expresses a particular ratio of product and reactant concentrations for a chemical system at any time
Kc
Choice, expresses a particular ratio of product and reaction concentrations for a chemical system at equilibrium expresses a particular ratio of product and reaction concentrations for a chemical system at equilibrium
True or false: All metal hydroxides are strong bases.
False
Which of the following options correctly describe strong acids and bases in aqueous solution? Select all that apply.
For a strong acid in water, [H3O+] is equal to the acid concentration. Strong bases dissociate completely in aqueous solution.
Which of the following reactions will not undergo a shift in equilibrium position when the volume or pressure changes? Select all that apply. Assume that each system is at equilibrium before changes occur, and that the temperature remains constant throughout.
H2(g) + Cl2(g) ⇄ 2HCl(g) N2(g) + O2(g) ⇄ 2NO(g)
Which statement correctly explains why even distilled and deionized H2O contains some ions?
H2O can autoionize, producing a small concentration of H3O+ and OH- ions.
Which of the following species could act as EITHER an acid OR a base? Select all that apply.
H2PO4- HCO3- H2O
Which of the following is NOT a conjugate acid-base pair?
H2PO4-/PO43-
Which of the following compounds are strong acids? Select all that apply.
HClO4 H2SO4 HI
Select the species from the list below that are not strong acids. Select all that apply.
HF HNO2 NH4+
The autoionization of water is a process whereby water ionizes to a small extent to form _____ ions and _____ ions
Hydronium; hydroxide
Which of the following statements correctly describe how a system at equilibrium will respond to a change in concentration of any species that appears in the expressions for QC and KC? Select all that apply.
If a reacting substance is added the equilibrium position will shift to use up the substance. If a reactant is removed from the system the equilibrium will shift toward the reactants. The value of Kc is not affected by changes in concentration.
Which of the following statements correctly describe how an equilibrium system containing gases will respond to changes in volume and/or pressure, if the temperature remains unchanged? Select all that apply.
If an inert gas is added there will be no effect on the equilibrium position. If the total number of moles of gas in the products and reactants is the same, a change in volume will not affect the equilibrium position. If the volume is decreased the reaction shifts in the direction that produces fewer moles of gas.
Which of the following options correctly describe how a system at equilibrium will respond to a change in temperature? Select all that apply.
If the forward reaction is exothermic, an increase in temperature causes a shift to the left. A change in temperature will cause a change in Kc.
For the exothermic reaction, CH4(g) + 2O2(g) ⇄ CO2(g) + 2H2O(g), match the effect of the applied stress on the equilibrium position.
Inc in temp - shift to the left Dec in vol - no shift Addtion of CH4 - shift to the right
Match the effect of each change described with the correct description of the resulting shift in equilibrium. Assume the system is at equilibrium before any change is made, and that all changes occur at constant temperature. SO2(g) + Cl2(g) ⇄ SO2Cl2(g)
Inc the vol of the container - equilibrium shifts toward the reactants Double the partial pressures of all species - Equilibrium will be unaffected Add 1 mol of Ne (g) - Equilibrium shifts toward the products
Match each of the following changes to the resulting effect on the pressure of an equilibrium system containing gaseous components.
Increase in vovlume - decrease in pressure Adding a gaseuous reactant - Increase in pressure Adding an inert gas - Increase in total pressure, but no change in partial pressures of gases Adding a solid - no effect on pressure
Consider the equilibrium system C2H4 (g) + H2O (g) ⇌ C2H5OH (g); ΔHo = -47.8 kJ. What will be observed if the temperature of the system is increased?
Kc will decrease. Equilibrium will shift toward the reactants.
A sample of solid C is placed in a sealed reaction vessel containing 2.0 atm H2 (g) and allowed to react according to the equation C (s) + 2H2 (g) ⇌ CH4 (g). At equilibrium the partial pressure of CH4 = 0.39 atm. Calculate Kp for the reaction.
Kp = 0.39(2.0-0.78)20.39(2.0-0.78)2 = 0.26 Reason: 2 mol of H2 will react to form every 1 mol of CH4, so P for H2 at equilibrium = 2.0 - 2(0.39). Kp = P(CH4)(/P(H2)) = 0.39/(2.0−0.78)2 = 0.26
Le Chatelier's principle states that when a chemical system at equilibrium is disturbed, the system will undergo a net reaction that _____ the effect of the disturbance and will attain a new _____ position.
Minimizes; equilibrium
What is the conjugate base of HNO2 if it reacts as a Bronsted acid in H2O?
NO2-
The hydrogen phosphate ion, HPO42-, can act as both a Bronsted acid and Bronsted base in water. Select all the options that correctly describe the reaction that occurs when HPO42- acts as a Bronsted base in water.
OH- is one of the products. H2O acts as the Bronsted acid. H2PO4- is one of the products.
Three common ways of disturbing a system at equilibrium are to change the concentrations of reactants and/or products, the temperature, or the _____ of the system
Pressure (or volume)
The equilibrium constant is a special value of the reaction _____ that occurs when reactant and product concentrations are at their _____ values.
Quotient; equilibrium
What does the term "shift to the right" mean when describing the response of a system at equilibrium to a disturbance? Select all that apply.
The concentrations of the products will increase until the system reaches equilibrium again. The reaction shifts toward the products until a new equilibrium state is established.
Given the reaction 2NO2(g) ⇄ 2NO(g) + O2(g), what will be observed as the volume of the container is increased, assuming that temperature remains constant? Select all that apply.
The equilibrium position will shift toward the products. The concentrations of all species will decrease at the instant the volume is changed.
Which of the following statements correctly explain why the addition of an inert gas to an equilibrium system involving gases does not cause a shift in the equilibrium position? Select all that apply.
The inert gas is not included in the expression for Q. The concentrations and the partial pressures of the gases involved in the reaction remain unchanged.
1.9 moles of HI are added to an evacuated, sealed 10.-L container and allowed to decompose according to the chemical equation: H2(g) + I2(g) ⇌ 2HI(g); Kc = 1.26 × 10−3H2(g) + I2(g) ⇌ 2HI(g); Kc = 1.26 × 10-3
The initial [HI] = 0.19 MHI = 0.19 M. Kc = 1.26 ×10−3 = (0.19 −2x)2x2Kc = 1.26 ×10-3 = (0.19 -2x)2x2 If the change in [H2] = +xH2 = +x, then at equilibrium [I2] = xI2 = x.
Which of the following statements accurately describe Bronsted-Lowry acid-base reactions? Select all that apply.
The reactants and products contain an acid and a base. Some species can act as either an acid or a base depending on the other species present.
If O2(g) is added to the equilibrium system 2NO(g) ⇄ N2(g) + O2(g), which of the following will be observed? Select all that apply.
The reaction will shift to the left. The concentration of NO will increase.
Calculate [OH-] in a solution that has [H3O+] = 6.7 x 10-2 M. Is the solution acidic or basic?
The solution is acidic. 1.5 x 10-13 M
Consider the equilibrium system C (s) + H2O (g) ⇌ CO (g) + H2 (g); ΔHo = 131 kJ. What will be observed if the temperature of the system is decreased? Select all that apply.
The value of Kc will decrease. The equilibrium concentration of H2O (g) will increase. Equilibrium will shift toward the reactants.
Match the equilibrium expression with the strategy used to solve for x. KC = 57 = (2x)2/(0.25−x)(0.25−x)
There is a squared term in the numerator and a squared term in the denominator, allowing us to take the square root of both sides of the equation.
KC = 5.9 × 10-10 = x/(0.24−x)(0.10−x)
When K is very small, the concentration change of any reactant or product will be small compared to any initial concentrations. The changes for nonzero initial concentrations can be neglected. KC = 5.9 × 10-10 = x(0.24)(0.10)
Which of the following statements correctly reflect Le Chatelier's principle? Select all that apply.
When a system at equilibrium is disturbed, Q ≠ K. When a system at equilibrium is disturbed, the system reacts to minimize the effect of the disturbance.
Which of the following options correctly represent the relationship between [H3O+] and [OH-] in aqueous solutions at 25oC? Select all that apply.
[H3O+] = 1.0 x 10^-14/[OH-] [H3O+][OH-] = 1.0 x 10^-14
Calculate the pH and [H3O+] of a 0.080 M solution of NaOH.
[H3O+] = 1.3 x 10-13 M pH = 12.90 Reason: pOH = -log(0.080) and pH = 14.00 - pOH and other equation SB won't let me put in here but it's like 1x 10^-14/0.080
Which of the following gives the correct mathematical operation required to calculate the [H3O+] given a pH of 5.0?
[H3O+] = 10-5.0
Which of the following options shows the correct mathematical operation required to calculate [H3O+] for a solution with a pH of 3.52?
[H3O+] = 10^-3.52 = 3.0 x 10^-4 M
In an aqueous solution at a given temperature, the product [H3O+][OH-] has a _____ value. This product is equal to _____ at 25oC.
constant, 1.0 x 10-14
If an equilibrium system contains gaseous reactants and/or products, a change in volume will cause a change in concentration and pressure. A decrease in volume will cause the system to shift in the direction that produces _____ moles of gas in total, whereas an increase in volume causes a shift in the direction that produces _____ moles of gas in total.
fewer; more
Acidic solutions have a _____ pOH than basic solutions.
higher (since the pH for an acdic solution is lower, the pOH will be higher).
As a reaction proceeds toward equilibrium from reactants to products (i.e., from left to right as written), the value of Q is _____.
increasing
The equilibrium constant for the reaction, A(g) ⇄ 2B(g)A(g) ⇄ 2B(g), is kc = 2.7 × 10−12kc = 2.7 × 10-12 and the initial reactant concentration is 0.5 M. Choose all of the statements that correctly describe how to determine the equilibrium concentrations of the reactant and product.
kc = 2.7 × 10−12 = [B]2[A] = (2x)20.50kc = 2.7 × 10-12 = [B]2[A] = (2x)20.50 The magnitude of kckc is very small and very little of A is used in the reaction. The change in concentration of A is negligible compared to the original concentration.
The higher the pH value, the _____ the [H3O+] and the _____ acidic the solution will be.
lower; less
Acidic solution
pH < 7.00
Calculate the pH and [OH-] of a solution of a 1.5 M solution of HCl.
pH = -0.18 [OH-] = 6.7 x 10-15 M
Which of the following mathematical relationships are correct for an aqueous solution at 25oC? Select all that apply.
pH = -log[H3O+] pOH + pH = 14.00
Place the following pH values in order of increasing [H3O+]. Star
pH = 8.5 pH = 7.2 pH =4.3
Basic solution
pH > 7.00
