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Chemistry

Which equation best describes an 0.10 M solution of a strong acid, such as hydroiodic acid (HI: K = 3 x 109)?

          (a) [H3O+]T ≈ CHI     (b) [H3O+]T ≈ [OH-]W     (c) [H3O+]T ≈ [HI]

         (d) [H3O+]T ≈ [H2O]    (e) [H3O+]T ≈ KaCa

Which of the following negative ions would be the strongest base?

         (a) Cl2CHCO2-  (Cl2CHCOC2H: Ka = 7.8 x 10-3)

         (b) ClCH2CO2-   (ClCH2CO2H: Ka = 1.4 x 10-3)

         (c) HCO2-  (HCO2H: Ka = 1.8 x 10-4)

          (d) CH3CO2- (CH3CO2H: Ka = 1.8 x 10-5)
 

What is the percent ionization in a 0.01 M HCN solution? (HCN: Ka = 4 x 10-10) (a) 0.002% (b) 0.02% (c) 0.2% (d) 2% (e) 20%

The value of the equilibrium constant, Ka for the dissociation of formic acid in water,

HCO2H(aq) + H2O(l) ⇌ HCO2-(aq) + H3O+(aq)

would depend on:

 (a) the temperature 

(b) the pressure 

(c) the pH

 (d) the concentration of HOAc

  (e) the concentration of the OAc- ion.

There are many ways to fluoridate water. One approach is to add a salt of the fluoride ion, such as NaF. Let's calculate the pH of a 0.15 M NaF solution. (HF: Ka = 7.2 x 10-4) (a) 2 (b) 5.8 (c) 8.2 (d) 10.9 (e) 12

The base-ionization constants for three bases, A(OH), B(OH), and C(OH), are 1.8 x 10-5, 4.4 x 10-4, and 7.4 x 10-4, respectively. Solutions of these bases, having equal molarity, exhibit a decrease in pH values in the following order: (a) A > B > C (b) B > C > A (c) C > B > A (d) A > C > B (e) B > A > C

A 0.10 M solution of a weak acid, HA, is found to be 1.50% ionized. Calculate Ka for this acid.

         (a) 1.5       (b) 2.3 x 10-1        (c) 2.3 x 10-5        (d) 2.3 x 10-6

         (e) none of the above
 

 What is the value of Kb for the formate ion if Ka for formic acid is 1.8 x 10-4?

(a) Kb = Kw x Ka        (b) Kb = Ka/Kw          (c) Kb = Kw/Ka

(d) Kb = Kw + Ka            (e) Kb = Kw - Ka

Ammonia and the ammonium ion form a conjugate acid-base pair.

         NH3(aq) + H2O(l) ⇌ NH4+(aq) + OH-(aq)

Calculate the pH of 0.10 M NH3 if Ka for the NH4+ ion is 5.6 x 10-10

 (a) 4.7 

(b) 5.1

 (c) 5.7 

(d) 8.9

 (e) 11.1
 

 Which of the following solutions would be the best buffer when a small amount of NaOH is added to the solution?

(a) a 1.0 L solution prepared by adding 0.10 mol of carbonic acid and 0.10 mol of sodium bicarbonate.

(b) a 1.0 L solution prepared by adding 0.20 mol of carbonic acid and 0.20 mol of sodium bicarbonate.

(c) a 1.0 L solution prepared by adding 0.10 mol of hydrochloric acid and 0.10 mol of sodium hydroxide.

(d) a 1.0 L solution prepared by adding 0.20 mol of hydrochloric acid and 0.20 mol of sodium hydroxide.

 (e) all of these solutions would have the same buffer capacity.

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