Question

1.) Calculate to four significant figures: a) the mass change in kg b) the energy change in kJ/mol,

when a neutron decays to produce a proton and an electron. The neutron, proton & electron masses are 1.67493 × 10^-27 kg, 1.67262 × 10^-27 kg and 9.10939 × 10^-31 kg, respectively.

2.) A chemical reaction of the general type:   A → 2B is first-order, with a rate constant of 1.52 × 10^-4 s^-1. a) Calculate the half-life of A. b) Assuming the initial concentration of A is 0.067 mol L^-1, calculate the time needed for the concentration to fall to 0.010 mol L^-1.

3.) The hypochlorite ion (OCl^-) is a strong oxidizing agent often found in household bleaches and disinfectants. It is also the active ingredient that forms when swimming pool water is treated with chlorine. In addition to its oxidizing abilities, the hypochlorite ion has a relatively high affinity for protons (it is a much stronger base than Cl^-, for example) and forms the weakly acidic hypochlorous acid (HOCl, K_a = 3.5 x 10^-8). Calculate the pH of a 0.100 M aqueous solution of hypochlorous acid.