Q: Which equilibrium constant represents a reaction that favors the reactants to the greatest extent?

$$K_{eq} = 1.0 \times 10$$^{-10}$$

Question 1

An equilibrium mixture of SO$$_2$$, O$$_2$$, and SO$$_3 at a $$certain temperature contains 0.180 M SO$$_2$$ and 0.0753 M O$$_2. $$The equilibrium constant $$K_c$$ equals 429 for the reaction:

$$2SO_2(g) + O_2$(g) \rightleftharpoons 2SO_3(g)$$

What is the equilibrium concentration of SO$$_3$$?

Accepted Answer

1.07 M

Question 2

The pH of a solution is 5.00 at 25°C. Which of the following is true about the solution?

Accepted Answer

The [H$$_3O$^+$$] is 1.0 × 10$$^{-5} M.$$

Question 3

Which of the pairs below represents an acid defined by its conjugate base?

Accepted Answer

H$$_2CO$_3 / CO$_3$$^{2-}$$

Question 4

Consider the following equilibrium:

$$A(g) \rightleftharpoons B(g)$$, $$K_c = 1.33 at 273 K

$$Which of the following diagrams represent the reaction mixture at equilibrium at 273 K? Each filled circle represents 1 mole of atom B, each empty circle represents 1 mole of atom A. Each flask has a volume of 1 L.

Accepted Answer

Flask 2 only

Question 5

Which equilibrium constant represents a reaction that favors the reactants to the greatest extent?

Accepted Answer

$$K_{eq} = 1.0 	imes 10$$^{-10}$$

Question 6

Which of the statements below is true concerning the solutions A and B?

Solution A: 0.10 M HNO$$_2$$ that has a $$K_a of$$ $$4.5 	imes 10$$^{-4}$$ at 25°C.
Solution B: 0.10 M HCl that has a K_a$ of 9.0$$ 	imes $$10^{18} at 25$$°C.

Accepted Answer

Solution B is more acidic than solution A.

Question 7

Consider the following equilibrium:

$$2H_2S(g) + 2SO_2(g) \rightleftharpoons 2H_2O(g) + 3S(s)$$, $$\Delta H = +130 kJ

$$Which of the following scenarios will favor the forward reaction (or shift the equilibrium to the right)?

Accepted Answer

Increasing the temperature

Question 8

What is the concentration of the aqueous OH$$^-$$ ion given that the concentration of the aqueous H$$_3O$^+$$ ion is 1.5 × 10$$^{-5} M at 25$$°C?

Accepted Answer

$$6.7 	imes 10$$^{-10}$$ M

Question 9

What is the acid dissociation expression for hydrofluoric acid reacting with water?

Accepted Answer

$$K_a = \frac{[H_3O^+][F^-]}{[HF]}$$

Question 10

A buffer solution is prepared by mixing equal concentrations of acetic acid and sodium acetate. If a small amount of HCl is added, what will happen to the pH of the solution?

Accepted Answer

The pH will decrease slightly.

Question 11

Which of the following is a correct statement about the relationship between $$K_c$$ and $$K_p$$ for a reaction involving gases?

Accepted Answer

$$K_p = K_c(RT$$)^{\Delta n}$$, where $$\Delta n$$ is the change in moles of gas.

Question 12

A solution has a pOH of 3.00. What is the concentration of OH$$^-$$ ions in the solution?

Accepted Answer

$$1.0 	imes 10$$^{-3}$$ M

Question 13

Which of the following will increase the solubility of a gas in water?

Accepted Answer

Increasing the pressure

Question 14

Which of the following is a correct statement about a strong acid?

Accepted Answer

It completely ionizes in water.

Question 15

A student mixes 0.10 M NH$$_3$$ and 0.10 M NH$$_4Cl in $$water. What is the primary function of this mixture?

Accepted Answer

To act as a buffer solution

Question 16

Which of the following is true for a reaction at equilibrium?

Accepted Answer

The rates of the forward and reverse reactions are equal.

Question 17

Which of the following will NOT affect the position of equilibrium in a chemical reaction?

Accepted Answer

Adding a catalyst

Question 18

A solution is prepared by dissolving 0.10 mol of NaOH in enough water to make 1.0 L of solution. What is the pH of the solution?

Accepted Answer

pH = 13.0

Question 19

Which of the following is the correct expression for the equilibrium constant $$K_c$$ for the reaction: $$N_2(g) + 3H_2(g$$) \rightleftharpoons 2NH_3(g)$$?

Accepted Answer

$$K_c = \frac{[NH_3$]^2}{[N_2$][H_2$]^3}$$

General Chemistry I – Chemical Equilibrium and Acid-Base Concepts: Study Notes

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