Q: A buffer solution is prepared using acetic acid and sodium acetate. Which equation correctly predicts its pH?

$$\mathrm{pH = pK_a + \log\left(\dfrac{\text{Salt}}{\text{Acid}}\right)}$$

Question 1

Which of the following best describes the state of chemical equilibrium in the reaction $$\mathrm{N_2$ + 3H_2 \rightleftharpoons 2NH_3}$$?

Accepted Answer

The rates of the forward and reverse reactions are equal.

Question 2

For the reaction $$\mathrm{H_2$ + I_2$ \rightleftharpoons 2HI}$$, the equilibrium constant $$K_c is $$given by which expression?

Accepted Answer

$$K_c = \dfrac{[HI]^2}{[H_2$][I_2$]}$$

Question 3

A saturated solution of $$\mathrm{AgCl} is $$prepared. If more $$\mathrm{NaCl} is $$added, what happens to the solubility of $$\mathrm{AgCl}$$ and why?

Accepted Answer

Solubility decreases because the added $$\mathrm{Cl^-}$$ suppresses ionization.

Question 4

Which of the following is the correct unit for the rate constant $$k in a $$second-order reaction?

Accepted Answer

$$\mathrm{L\,$$mol^{-1}$$\,s$$^{-1}$$}$$

Question 5

A buffer solution is prepared using acetic acid and sodium acetate. Which equation correctly predicts its pH?

Accepted Answer

$$\mathrm{pH = pK_a + \log\left(\dfrac{	ext{Salt}}{	ext{Acid}}ight)}$$

Question 6

If the reaction quotient $$Q_c$$ for a reaction is less than the equilibrium constant $$K_c$$, what will happen to the system?

Accepted Answer

The reaction will shift toward the products.

Question 7

Which factor does NOT affect the rate of a chemical reaction?

Accepted Answer

Color of the reactants

Question 8

According to the Arrhenius equation $$k = Ae$$^{-E_a/RT}$$, what happens to the rate constant k$ if the activation energy E_a$ increases, assuming all other factors remain constant?

Accepted Answer

The rate constant $$k$$ decreases.

Question 9

A reaction has the rate law $$\mathrm{Rate = k[A]^2[B]}. $$What is the order of the reaction?

Accepted Answer

Third order

Question 10

A catalyst increases the rate of a reaction by:

Accepted Answer

Decreasing the activation energy

Question 11

In a medical laboratory, a buffer solution is used to maintain blood pH. If a small amount of acid is added, what happens to the pH?

Accepted Answer

The pH remains nearly constant.

Question 12

For the reaction $$\mathrm{$$CaF_2$$ \rightleftharpoons Ca$$^{2+}$$ + 2F^-}$$, the solubility product $$K_{sp} is $$expressed as:

Accepted Answer

$$K_{sp} = [Ca$$^{2+}$$][F^-]^2$$

Question 13

A student mixes $$\mathrm{Ba(NO_3$)_2}$$ and $$\mathrm{Na_2SO_4} in $$water. If $$Q_{sp}$$ for $$\mathrm{$$BaSO_4$$} is $$greater than $$K_{sp}$$, what will happen?

Accepted Answer

A precipitate of $$\mathrm{$$BaSO_4$$}$$ will form.

Question 14

Which scenario best illustrates Le Chatelier's Principle?

Accepted Answer

Increasing the temperature of an exothermic reaction causes the equilibrium to shift toward the reactants.

Question 15

In a reaction, the rate is measured as $$\mathrm{\Delta C/\Delta t}. $$What does $$\mathrm{\Delta C}$$ represent?

Accepted Answer

Change in concentration

Question 16

A reaction has a rate law $$\mathrm{Rate = k[A][B]}. If $$the concentration of $$\mathrm{A} is $$doubled and $$\mathrm{B} is $$tripled, by what factor does the rate increase?

Accepted Answer

6

Question 17

Which of the following statements about reversible reactions is correct?

Accepted Answer

They proceed in both forward and reverse directions.

Question 18

In industrial ammonia synthesis ($$\mathrm{N_2$ + 3H_2 \rightleftharpoons 2NH_3}$$), increasing the pressure favors the formation of ammonia. Why?

Accepted Answer

Because the reaction produces fewer gas molecules.

Question 19

Which of the following best explains why a catalyst does not affect the equilibrium constant $$K_c$$?

Accepted Answer

A catalyst increases the rate of both forward and reverse reactions equally.

Chemical Equilibrium and Reaction Kinetics: Core Concepts and Applications

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