I am working on the biodecompostion lab for chem 111. I am having difficulty with some of the calculations.

I am working on the biodecompostion lab for chem 111. I am having difficulty with some of the calculations. Is my mass of H2O2 solution the weight I recorded for each trial or is it the mass of H2o2 solution in the sample? How would I then calculate the moles of H2o2, the theoretical moles of O2 produced, the theoretical volume of O2 produced (mls) and the percent error in volume?