Big V

the question is:
Sodium Hydrogen carbonate (baking soda) is reacted with excess acetic acid (vinegar) with a concentration of 0.500mol/L in an Erlenmeyer flsk. The proucts are sodium acetate, water and carbon dioxide gas. The gas produced is collected in a balloon attached to the flask, tied off with a string and then weighed. Using the information from the data below, predict the mas of carbon dioxide produced and the percent error in the experiment.

other data given :
Mass of... balloon (g) 13.5
string (g) 1.2
balloon, string, gas (g) 16.5
solute (g) 5.0

the part i don't get is which number do i use to find moles so that later i can use those moles to find the mass . like is the mass of solute (5.0) , the mass of sodium hydrogen carbonate.
please help sorry if i'm confussing