Le Chatelier's Acids Bases Intro
A solution containing 15.0mL of 4.00MHNO3 is diluted to a volume of 1.00L. What is the pH of the solution?
1.22
Which of the following reactions shows water acting as the conjugate base of an acid?
H3O+ + HPO2−4 ↽−−⇀ H2PO−4 + H2O
What will happen to the following equilibrium reaction if the volume of the container in which the gasses are contained decreases? 2NO2(g)+O2(g)⇌2NO(g)
It will shift to the right.
If we plug equilibrium concentrations into the reaction quotient expression, we should be able to calculate:
Kc
Which of the following gives the definition of percent ionization of a weak acid?
Percent ionization is the ratio of the concentration of the ionized acid at equilibrium to the initial acid concentration times 100%.
Which of the following is true of water in a base ionization reaction?
Water loses a proton and is acting as an acid.
Catalysts are typically in the:
any phase
The catalyst used in the industrial production of ammonia:
enables equilibrium to be reached more quickly
A change in pressure will have an effect on:
gaseous equilibria
Which of the following is NOT a strong acid?
hydrofluoric acid
For the following equilibrium: N2+3H2→2NH3change in enthalpy=−92.2 kJ The presence of catalyst speeds up the forward reaction which is most likely to be favored when there is:
increased pressure
What is the term used to describe the equilibrium constant for the autoionization of water?
ion-product constant
Based on the following equation, if the pressure decreases, the equilibrium will shift: N2(g)+3H2(g)↽−−⇀2NH3(g)
left
If an equilibrium reaction is exothermic in the forward direction, the change in enthalpy of the reaction will have a _______ sign, and the heat produced in the forward reaction can be listed as a _________.
negative, product
In the industrial production of ammonia, which of the following is affected by the catalyst? Select all that apply.
- the rate of production - the practical yield that can be obtained in limited time
According to the Bronsted-Lowry definition, what acts as the acid when the reaction below proceeds in the forward direction? H2O+HSO−4⇌SO2−4+H3O+
HSO4^-
As a system shifts to alleviate a stress, it will continue to do so until:
Q = K
Of the following, which are characteristics of basic solutions? Select all that apply.
- Greater concentration of hydroxide ions than hydronium ions - [H3O+] < [OH−]
Identify the options below that are results of decreasing the temperature of a system that includes an exothermic reaction in the forward direction.
- The concentrations of the products increase. - The equilibrium shifts toward the products.
Consider the reversible reaction in aqueous medium shown below. At equilibrium, the concentrations of A, B, and C are 0.0102 M, 0.0127 M, and 0.0064 M, respectively. What is the equilibrium constant for the reaction? 3A⇌2B+2C
.0062
A solution containing 572.0mL of 0.6300MHCl is diluted to a volume of 1.000L. What is the pH of this solution?
0.4433
A solution containing 175mL of 1.50MHBr is diluted to a volume of 1.00L. What is the pH of this solution?
0.581
The hydronium concentration of a solution is equal to:
10^-pH
Calculate the hydronium ion concentration of a solution with a pH of −1.07.
12 M
For the reaction below, the concentrations at equilibrium are [SO2]=0.80 M,[O2]=0.25 M, and [SO3]=1.5 M. What is the value of the equilibrium constant, Kc? 2SO2(g)+O2(g)⇌2SO3(g)
14
Hydrogen gas and gaseous iodine will react to form hydrogen iodide, as described by the following chemical equation. H2(g)+I2(g)↽−−⇀2HI(g)Kc(400.∘C)=50.0 Assume that all of the HI(g) is removed from a vessel containing this reaction, and equilibrium is re-established. What will be the new equilibrium concentration of HI if the equilibrium concentrations of H2 is 0.450M and I2 is 0.450M?
3.18 M
The initial concentration of acid HA in solution is 0.39 M. If the pH of the solution at equilibrium is 0.76, what is the percent ionization of the acid?
45%
What is the hydroxide ion concentration in a solution of pH 3.71? Remember to report your answer with the correct number of significant figures.
5.1 x 10^-11
At 10∘C, the ion product of water is 2.93×10−15. What is the concentration of hydronium ions at this temperature?
5.41 x 10^-8
A solution has a pH of 7.5 at 50∘C. What is the pOH of the solution given that Kw=8.48×10−14 at this temperature?
5.6
Which value for Kc indicates an equilibrium that strongly favors products?
981
An equilibrium constant is described by which of the following?
An equilibrium constant is the value of the reaction quotient for a system at equilibrium.
The Bronsted-Lowry definition of acids and bases refers to the transfer of a "proton" from the acid to the base; however, the symbol for a proton (p+) is not generally used in this context. What is the chemical symbol that is commonly used to represent a "proton" in the context of Bronsted-Lowry acids and bases? Enter a chemical symbol that can be considered equivalent to a single proton.
H^+
What is the conjugate base of NH3?
NH2^-
Calculate the reaction quotient and determine the direction in which the following reaction will proceed to reach equilibrium. [SO3]=0.28 M,[SO2]=0.12 M, and [O2]=0.040 M2SO3(g)⇌2SO2(g)+O2(g) Kc=0.230
Qc=7.3×10−3 and the reaction will shift right
Of the following, which is not a result of increasing the temperature of a system that includes an endothermic reaction in the forward direction?
The concentrations of the reactants increase.
Of the following, which is not a result of adding more of a reactant to a chemical system at equilibrium?
The value of K increases.
A small amount of reactant is removed from a system at equilibrium. Which of the following will change?
The value of Q
Changing the temperature of a system at equilibrium:
changes the value of the equilibrium constant
Any compound that is more acidic than the hydronium ion will undergo what type of ionization?
complete ionization
The hydronium ion concentration of vinegar is approximately 4.0×10−3 M. What are the corresponding values of pOH and pH?
pH = 2.40, pOH = 11.60
Identify the option below that is a characteristic of acidic solutions.
pOH levels greater than 7 at 25∘C
A stress on a system can be considered anything that will alter the:
position of the equilibrium
If the forward reaction of an equilibrium is endothermic, the ΔH will have a _______ sign, and the heat can be thought of as a _________.
positive, reactant
One way to increase the amount of ammonia produced in an industrial setting is to increase the ________ on the system.
pressure
Heat is abbreviated as:
q
Given a reaction that is exothermic in the forward direction, if the temperature is decreased, which way will the equilibrium shift?
right
Suppose an extra 0.2 mol of gas B are added to an equilibrium mixture described by the reaction below. In which direction do you predict the equilibrium to shift? A(g)+B(g)⇋C(g)+D(g)
right
For the following equilibrium, what will occur if the vessel contracts: C(s)+H2O(g)⇌CO(g)+H2(g)
shift left
If more products are added to a system at equilibrium, the equilibrium will:
shift left
If reactants are removed from a system at equilibrium, the equilibrium will:
shift left
For the following equilibrium, what will occur if the vessel expands: 2O3(g)→3O2(g)
shift right
If products are removed from a system at equilibrium, the equilibrium will:
shift right
Catalysts are primarily used in a reaction to _______.
speed up the reaction
If a stress causes the value of Q to increase, what will happen to the system?
the rate of the reverse reaction will increase
If a hot and cold object come into contact, heat is transferred until:
thermal equilibrium is reached
A small amount of product is removed from a system at equilibrium. Which of the following will change? Select all that apply.
- The amount of reactants - The value of Q
Which of the following can result in a change in equilibrium in a reaction involving gases? Select all that apply.
- decreasing the volume of the system to half of its original value - increasing the volume of the system to twice its original value - doubling the amount of one of the components in the system - doubling the amount of all of the components in the system
Which of the following has the potential to change the equilibrium in a reaction involving gases? Select all that apply.
- decreasing the volume of the system to half of its original value - increasing the volume of the system to twice its original value - doubling the amount of one of the components in the system - doubling the amount of all of the components in the system
A catalyst has no effect on: (select all that apply)
- value of an equilibrium constant - equilibrium concentrations
If a neutral acid donates a proton, the conjugate base will have a charge of _______.
-1
What is the hydronium ion concentration in a solution of pH 10.90?
1.3 x 10^-11
In a model that precedes the Bronsted-Lowry model, a base is defined as something that __________.
dissociates in water to yield hydroxide ions
For a particular reaction, the change in enthalpy is 51kJmole and the activation energy is 109kJmole. Which of the following could NOT be the change in enthalpy (ΔH) and the activation energy (Ea), respectively, for the catalyzed reaction?
- 34kJmole,83kJmole - 34kJmole,120kJmole - 51kJmole,120kJmole
For the following equilibrium: H2+I2⇌2HIKc=50.0 at 400∘C If some of the H2 is removed from a mixture at equilibrium, which of the following changes to the concentrations of I2 and HI will occur as equilibrium is reestablished? Select all that apply.
- The concentration of I2 will increase. - The concentration of HI will decrease.
An endothermic reaction proceeds in the forward direction. Which of the following statements will be true if the temperature at which the reaction occurs is decreased? (select all that apply)
- The concentrations of the products decrease. - The equilibrium constant decreases.
Which of the following are results of increasing the temperature of a system that includes an endothermic reaction in the forward direction?
- The concentrations of the products increase. - The concentrations of the reactants decrease.
Which of the following statements about strong acids are true?
- The conjugate base of a strong acid has negligible acid-base properties. - They produce stable ions that have little tendency to accept a proton.
Of the following, which are not results of adding a catalyst to a chemical system at equilibrium?
- The reaction shifts toward the reactants. - The reaction quotient increases. - The equilibrium constant increases.
A strong acid has _______. (select all that apply)
- a large percent ionization - a large Ka value
A sample of carbon dioxide in water at room temperature has a hydronium ion concentration of 6.4×10−6 M. What is the hydroxide ion concentration of the solution?
1.6 x 10^-9
At a particular temperature, a sample of pure water has a hydronium concentration of 5.4×10−8 M. Which of the following might be the temperature of the sample?
10 degrees celcius
The hydroxide concentration of a solution is equal to:
10-pOH
At a particular temperature, a sample of pure water has a Kw of 7.7×10−14. What is the hydroxide concentration of this sample?
2.8 x 10^-7
At about 10.∘C, a sample of pure water has a hydronium concentration of 5.4×10−8 M. What is the equilibrium constant, Kw, of water at this temperature?
2.9 x 10^-15
A solution has a pOH of 9.40 at 50∘C. What is the pH of the solution given that Kw=5.48×10−14 at this temperature?
3.86
A solution has a pOH of 8.5 at 50∘C. What is the pH of the solution given that Kw=5.48×10−14 at this temperature?
4.8
What is the hydroxide ion concentration in a solution of pOH 8.14?
7.2 x 10^-9
A solution has a pOH of 7.1 at 10∘C. What is the pH of the solution given that Kw=2.93×10−15 at this temperature? Remember to report your answer with the correct number of significant figures.
7.4
What is the hydroxide ion concentration of a solution at 25∘C with a pH=9.90?
7.9 x 10^-5
Typically, the rate of a chemical reaction will increase with increasing temperature; however, increasing the temperature of an exothermic reaction will cause the equilibrium to shift toward the reactants. How can a catalyst be used to increase the yield of products at low temperatures?
A catalyst increases the rate of reaction, and will cause a system to reach equilibrium more quickly
What will determine the number of moles of hydronium in an aqueous solution of a strong monoprotic acid?
The amount of acid that was added.
Which of the following is a result of increasing the temperature of a system that includes a reaction in the forward direction that is exothermic?
The equilibrium constant decreases.
Of the following, which is a result of decreasing the temperature of an exothermic system?
The equilibrium constant increases.
A system involves a chemical reaction that is exothermic in the forward direction. How will the equilibrium shift if the temperature of the system is decreased?
The equilibrium will shift towards the products.
Which of the the following will be the result of adding more of a product to a chemical system at equilibrium?
The reaction shifts toward the reactants.
A chemical reaction is at equilibrium. In which of the following circumstances would a change in temperature be least likely to affect the equilibrium of a chemical reaction?
When there is no change in enthalpy between the reactants and the products.
Percent ionization for an aqueous acid can be expressed as:
[H3O+]eq / [HA]i×100%, where "eq" stands for equilibrium and "i" stands for initial
Which will cause the following equilibrium to shift to the right? 2H2(g)+S2(g)⇌2H2S(g)
a decrease in the volume of the vessel in which the reaction is contained
Shown below is the formation reaction of ammonia. How does the catalyst used in the industrial production of ammonia affect the activation energies of the forward and reverse reactions? N2+3H2⇌2NH3
activation energy decreased both the forward and reverse reactions
A system at equilibrium has two aqueous products and two aqueous reactants. An additional amount of one of the products is added to the system. After the addition of one product, which of the following will change?
all of the above (- the concentration of the added product - the concentration of the other product - the concentrations of the reactants)
A reaction that produces ammonia is shown below. How does the catalyst used in the industrial production of ammonia affect the reaction rates of the forward and reverse reactions? N2+3H2⇌2NH3
both the forward and reverse rates increase
An increase in temperature will cause an equilibrium to:
depends on the equilibrium
Based on the following equation, if the concentration of CH3OH(g) doubles, the equilibrium will shift: CO(g)+2H2(g)↽−−⇀CH3OH(g)
left
Given a reaction that is endothermic in the forward direction, if the temperature is decreased, which way will the equilibrium shift?
left
For the following equilibrium, what will occur if the vessel contracts: H2(g)+I2(g)⇌2HI(g)
no change
For the following equilibrium, what will occur if the vessel expands: H2(g)+Cl2(g)→2HCl(g)
no change
Consider the reaction described by the following equation. CO2(g)+H2(g)⇌CO(g)+H2O(g) How will the position of the equilibrium change if the volume of a vessel that contains this reaction is decreased?
no change will be observed
When considering the effects of concentration changes, reducing the amount of a product _______.
results in a value of Q that is less than K
For the following equation, if heat is decreased, the equilibrium will shift: H2+I2↽−−⇀2HI+heatΔH=−9.4kJ
right
Which of the following will NOT result in a change in equilibrium in a reaction involving gases?
tripling the amount of all of the components in the system
Roughly how many water molecules are ionized at any given time in a sample of room-temperature water?
two in a billion