stoichiometry ,gas problem

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

symbolipoint

Determine these two pieces of information first:

Write the balanced reaction.
Compute how much gas is in the baloon.

You said that the acetic acid is in excess, so the limiting reactant must be the sodium bicarbonate.

Big V

balanced reaction :
(this is how i would set up my data)
CH3COOH + NaHCO3 → CH3COONa + H2O + CO2
C= 0.500mol/l________________________ m=?

Gas in Balloon:
16.5-1.2=15.3
-13.5= 1.8
gas =1.8g