1. Dinitrogen tetroxide decomposes to nitrogen dioxide: At 298 K, a reaction vessel initially contains 0.100 atm of N2O4. When equilibrium is reached, 58% of the N2O4 has been decomposed to NO2. What percentage of N2O4 decomposes at 388 K? Assume that the initial pressure of N2O4 is the same (0.100 atm).

2. Acetic acid, CH3COOH, is one of simple buffering agents and its Ka is 1.76 x 10-5.

(a) Calculate the pH of a 500.0-mL solution of acetic acid, in which 30.025-g pure acetic acid is dissolved;

(b) Calculate the pH of a 1.500-L solution of sodium acetate, CH3COONa, in which 123.05-g pure sodium acetate is dissolved;

(c) To make a buffer solution with pH = 5.00, what is the volume of the sodium acetate solution in part (b) required to add into the solution in part (a). Assume the volume of mixed solution is additive.

3. The pH of a 0.250-M solution of sodium nitrite, NaNO2, is 8.37. Determine the Ka of nitrous acid, HNO3. Calculate the pH of a 0.0100-M solution of sodium nitrite.

4. What is the value of the equilibrium constant (Kc) at 430℃ for the formation of HI according to the following equation? H2(g) + I2(g) --> 2HI(g)

An equilibrium mixture of H2(g), I2(g), and HI(g) at 430℃ was found to contain 1.15-M H2, 1.35-M I2, and 9.18-M HI. Calculate Kp based on the Kc.

If the reaction starts with HI only and its concentration is 1.326 M, calculate the concentrations of H2(g), I2(g), and HI(g)when the equilibrium is reached.