Question

1) What is the pH of a 0.100 M NH4Cl(aq) solution?

2) The reaction A(aq) + B(aq) → 2C(aq) has an equilibrium constant of K_c= 5.2. If the initial concentrations are [A] = 0.100 M, [B] = 0.000 M, and [C] = 0.500 M, what are the concentrations of A, B, and C at equilibrium?

3) What are the concentrations of H₃O⁺, H₃PO₄, H₂PO₄^-, and HPO₄^2- in a 0.100 M H₃PO₄(aq) solution? (In this solution, 0.100 M would be the concentration of H₃PO₄ if none of it dissociated.)

4) The reaction ½A(g) + ½B(s) → C(g) has an equilibrium constant of K_c = 3.5x10^-2. What is the K_p for the reaction A(g) + B(s) → 2C(g)? Use atm as the pressure unit. (Note that the question gives a K_c but asks for a K_p.)  

5) The reaction A → B + C is first order. Two experiments are performed, both with [A] = 0.100 M at t =0. In the first experiment, which is performed at 25.0°C, [A] = 0.0600 M at t = 100.0 s. In the second experiment, which is performed at 75.0°C, [A] = 0.0100 M at t = 5.00 s.   Calculate the activation energy for this reaction. Give your answer in kJ/mol.

Answer 1