ChemistryName :

Test review - problemsDate :

1. Complete and balance the following neutralization reactions.

a. H2SO4 + Al(OH) 3 ------>

b. H2CO3 + NaOH ------>

c. HNO3 + Ca(OH) 2 ------>

2. Write and balance the following neutralization reaction and then determine how many moles of phosphoric acid will be neutralized by the given amounts of zinc hydroxide or vice versa. (Assume all three hydrogen atoms of phosphoric acid are ionizable).

H3PO4 + Zn(OH) 2 ------>

a. How many moles of phosphoric acid are needed to neutralize 2.20 moles of Zn(OH) 2 ?

b. How many moles of Zn(OH) 2 are needed to neutralize 1.50 moles of H3PO4 ?

3. Calculate the unknown concentrations (in molarity) from the information given in the problem.

a. What is the concentration of a 80.0 mL solution of H2SO4 which is neutralized by 50.0 mL of a .50M solution of Ca(OH) 2 ?

4. Determine the gram equivalent mass of the following acids or bases.

a. LiOH

b. H2SO3

c. HC2H3O2

d. Zn(OH) 2

5. Calculate the normality of the following solutions from their given molarities.

a. .040 M H2SO4 = ______

b. .50 M H3PO4 = ______

c. .10 M Al(OH) 3 = ______

d. 1.35 M HCl = ______

e. .200 M Ca(OH) 2 = ______

6. Calculate the normality of the following solutions.

a. 8.50 g of H3PO4 in 500.0 mL of solution.

b. 35.0 g of Zn(OH) 2 in 750.0 mL of solution.

c. 4.77 g of HNO3 in 350.0 mL of solution.

7. Calculate the number of equivalents in the following.

a. 450.0 mL of a 2.2 N solution of nitric acid (HNO3).

b. .060 L of a .060 N solution of calcium hydroxide (Ca(OH) 2).

c. 550.0 mL of a 2.50 N solution of potassium hydroxide (KOH).

d. 950.0 mL of a 2.10 N solution of phosphoric acid (H3PO4).

8. Dilution problems:

a. What volume would 150.0 mL of a 5.0N solution of nitric acid need to be diluted to get a .080N solution of nitric acid?

b. What would be the normality of a solution made by diluting 250.0 mL of a 12.0 N solution of sodium hydroxide to 1500.0 mL?

9. Titration problems :

a. If 80.0 mL of .20 N hydrochloric acid is used to neutralize 80.0 mL of an unknown base, what is

the normality of the base?

b. 55.0 mL of a 3.0N acid is used to neutralize 200.0 mL of a base. What is the normality of the

base?

10. Salt hydrolysis:

a. Write and balance the equation for the neutralization reaction between hydrocyanic acid (weak)

(HCN) and potassium hydroxide (strong) KOH).

b. Write the equation for the dissociation of the salt formed in the above reaction.

c. Write and balance the reaction of the anion (negative ion) of the salt with water to show how water

is split to form a basic solution(a solution containing hydroxyl ions) is formed.

11. The following reaction is an equilibrium reaction of aqueous cyanic acid (weak) and the cyanide ion of one of its salts. The cation (positive ion of the salt) has been left out because it is only a spectator ion (does not enter into the reaction). Answer the true/false questions below based on this equation.

HCN + H2O <======> H3O+ + CN-

_____(T/F) If a base is added to the above solution it will neutralize (remove) some of the hydronium ions.

_____(T/F) According to Le Chatelier's principle the above reaction will shift to the left if a base is added.

_____(T/F) According to Le Chatelier's principle the above reaction will shift to the right if an acid is added.

_____(T/F) If either a small amount of an acid or a small amount of a base is added to the above reaction the pH will remain relatively constant.

12. What is the pH of a 1.2M solution of the F- ion (Kb = 1.48 x 10-11)

13. What is the Ka of the HCO3- ion if a 0.45 M concentration has a pH of 5.30?

14. Solubility product constant problems.

a. What is the [I-] if the Ksp of silver iodide (AgI) is 8.3 x 10-17?

b. What is the [Ag+] if the Ksp of silver sulfide (Ag2S) is 8.0 x 10-51?

15. a. What is the Ksp of cadmium sulfide (CdS) if it has a solubility of 3.16 x 10-14 mol/L at 25 °C?

b. What is the Ksp of calcium hydroxide (Ca(OH)2) if its solubility is .0118 M at 25 °C?

16. a. What is the solubility of lead(II) sulfide (Ksp = 3.0 x 10-28) in a .025 M solution of sodium sulfide?

b. What is the solubility of zinc hydroxide (Zn(OH)2) (Ksp = 3.0 x 10-34) in water at 25 °C?

17. What is the solubility of zinc hydroxide in a buffer with a pH of 8.60?

Equations to use :

Calculation of molarity from balanced equation and known volume and concentration:

step 1. Write the balanced equation :

step 2. Calculate moles of given used.

step 3. Calculate moles of unknown neutralized.

step 4. Calculate molarity of unknown.

gem = molar mass/moles of H+ or OH- produced per mole

N= Molarity x number of moles of H+ or OH- produced per mole

no. of equivalents = mass of sample x (1 eq./gem)

N= no. of eq./L

no. of equiv = N x V (in L)

Dilution : N1 x V1 = N2 x V2

Titration : NA x VA = NB x VB

Ksp problems :

step 1. Write and balance dissociation equation.

step 2. Write expression for Ksp.

step 3. Solve for unknown.

Salt Hydrolysis

  1. Show the balanced equation between the acid and base.
  2. Show the dissociation of the salt into its ions.
  3. Show how one of the ions will split water to form a basic or acidic solution.

Answers : 1a. 3 H2SO4 + 2 Al(OH) 3 ------> Al2(SO4) 3 + 6 H2O

b. H2CO3 + 2 NaOH ------> Na2CO3 + 2 H2O

c. 2 HNO3 + Ca(OH) 2 ------> Ca(NO3) 2 + 2 H2O

2. 2 H3PO4 + 3 Zn(OH) 2 ------> Zn3(PO4) 2 + 6 H2O

2a. 1.47 moles 2c. 2.25 moles 3a. .31M 4a. 23.95g 4b. 41.04g 4c. 60.06g 4d. 49.70g 5a. .080N 5b. 1.5 N 5c. .30 N 5d. 1.35N 5e. .400N 6a. .520 N 6b. .939N 6c. .216 N 7a. .99 eq. 7b. .0036 eq. 7c. 1.38 eq. 7d. 2.00 eq. 8a. 9 400 mL 8b. 2.00N 9a. .20N 9b. .83 N 10a. HCN + KOH ----> KCN + H2O 10b. KCN ---> K+ + CN- 10c. CN- + H2O ----> HCN + OH- 11. T,F,F,T 12. 8.62 13. 5.6 x 10-11 14a. [I-] = 9.1 x 10-9 14b. [Ag+] = 2.6 x 10-17 15a. 9.99 x 10-28 15b. 6.57 x 10-6 16.a. 1.2 x 10-26 16b. 3.0 x 10-20 17. 1.89 x 10-23