CHEM_100 2012

ASSIGNMENT #4 Due to November 19

Chemical equilibrium (chapter 15 and 16)

1. {10} The 0.42 moles of CO and 0.42 mol of H₂ were placed in an empty 1.00-L container and allowed to reach equilibrium described by the equation:

CO (g) + 2H₂ (g) D CH₃OH (g)

At the equilibrium there were 0.29 mol CO remaining. What is K_eq ?

CO (g) + 2H₂ (g) D CH₃OH (g)

2. {15} For the reaction I₂ (g) + Br₂ (g) D 2 IBr (g) , K_c = 280.0 at 150.0⁰ C

1.00 mol of IBr in a 2.00-L flask is allowed to reach equilibrium at 150⁰C. What are the equilibrium concentrations of IBr, Br₂, and I₂ ?

3. {15} A mixture of 1.374 g H₂ and 70.31 g of Br₂ is heated in a 2-L vessel at 700 K. The reaction runs as follows:

H₂ (g) + Br₂ (g) D 2 HBr (g)

At equilibrium the vessel contains 0.566g of H₂.

a) {10} Calculate the equilibrium concentrations of H₂, Br₂, and HBr.

b) Calculate K_c.

4.{10}

(a){2} Give a definition for Arrhenius acid and base

(b) {2} Give a definition for Brønsted -Lowry acid and base

(c) {2} Write down the equation for and value of K_w at 25^oC

(d) {4} at 25^oC, pH+ pOH=

pH=

pOH=

[H⁺] = [OH^-]=

5. {5} Write down conjugate bases for the following acids:

HCl HCO₃^- OH^- CH₄ CH₃COOH

6. {5} Calculate the pH of a solution at 25^OC, which contains 1.94 x 10^-10 M hydronium ions

7. {5} Calculate the molarity of H₃O⁺ at 25⁰C in a solution with pOH=4.233

8. {5} A 2.00-L aqueous solution contains 0.150 mol of HCl at 25⁰C. Calculate pH.

9. {15} The pH of a 0.15M solution of the weak acid, HA, at 25⁰C is 5.35.

(a) {10} Calculate K_a of HA.

(b) {5} Calculate the percent ionization of HA

10. {10}. The K_a of hypochlorous acid, HClO, is 3.00x 10^-8. What is pH at 25.⁰C of a 0.0200M solution of HClO?

11. {5} The pH of a 0.10M solution of a weak base is 10.0. What is K_b?