Someone check my answer please. :) 1. The problem statement, all variables and given/known data The rate of decomposition of hydrogen peroxide was studied at a particular temperature. H2O2(aq) = H2O (l) + 1/2O2(g) The initial concentration of hydrogen peroxide was 0.200 mol/L. 10.0 s later, it was measured to be 0.196 mol/L. b) 0.500 L of hydrogen peroxide solution was used for the experiment. What mass was lost as O2 bubbled out of solution in this initial 10.0 s interval? 3. The attempt at a solution What I did was. 0.500 L * 0.200 mol/L = 0.1 0.500 L * 0.196 mol/L = 0.098 0.1 - 0.098 = 0.002mol 0.002 * 16 = 0.032 g What I'm doubting is. 0.500 L * 0.196 mol/L = 0.098 Won't the volume change after 10 seconds?