
Originally Posted by
PhDemon
To try and help you out, I suggest you write down the chemical equation for the reaction. What gas is given off? Does this gas support combustion and based on this answer what will it do to a lit splint?
EDIT TO ADD: I see on re-reading you have the answer to the first part...
For the next part did you weight the gas given off in the reaction? If not there is your missing mass right there. To verify the law collect the gas, measure it's volume and from the ideal gas law you can calculate the number of moles and the mass of gas. If the mass of the gas is added to the mass of the other products mass is seen to be conserved.