I need help with calculating the molar enthalpy of reaction.

This is the question: Calculate the molar heat of reaction for the NaOH(aq) using the data obtained from this experiment. Show all your work.

The thing I am having a problem with is how to get mass of water. This is what I mean. I need to get the quantity of thermal energy from this formula

Q=mc?t

I don't know where to get (m) mass of water, so I am unable to get Q and therefore am unable to get molar heat reaction.

I hope you understand what I mean, and if you think you can help me, but can't understand what I mean then just email me.