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Acid-Base Equilibria.

1. Write formulas for the conjugate bases for each of these acids:

a) HCl

b) CH4

c) HSO3-

d) H2SO4

e) NH3

2. In the following reactions, identify the Lewis acid and the Lewis base:

a) Fe3+ + 6H2O ←→ Fe(H2O)36+

b) BF3 + NH3 ←→ F3BNH3

c) BF3 + F- ←→ BF4-

d) H+ + Cl- ←→ HCl

3. A solution of hydrofuoric acid contains 2.0g of HF per litre and has a pH of 2.2. What is the dissociation constant for HF?

4. The formation of products is strongly favoured in this acid-base system:
The equilibrium involved in the process is:

HX + B- ←→ HB + X-

a) Identify the bases competing for protons.

b) Which base is stronger?

c) Which is the weaker acid, HX or HB?

d) Does the K for this system have a large or small value?

e) How is the equilibrium affected by the addition of the soluble salt NaB?

5. Buffer solutions have the unique ability to resist changes in pH when an acid or base is added to them. One important buffer system that helps to maintain blood pH at a constant value of 7.4 is the hydrogen phosphate buffer. The chemical equation for this buffer system is:
H2PO4-(aq) + H2O(l) ←→ H3O+(aq) + HPO42-

Use Le Chatelier's Principle to explain why the pH of a hydrogen phosphate buffer system remains constant when:

a) small amounts of acid are added

b) small amounts of base are added

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Solution Summary

The solution examines acid-base equilibria.

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