The question is asking how much NaCl will be produced from Cl and Na.
We are given the mass of Na = 8.30g, which is the limiting reagent because we are told that Cl2 is in excess.
Let us first balance the equation:
2Na + Cl2 = 2NaCl
The first thing to do is to calculate the number of moles of Na.
n=m/M where m is the mass of Na and M is the molar mass
n=8.30g/22.99g/mol
n= 0.36 mol
Now we can use the stoichiometry to calculate the number of moles for NaCl.
So for every 2 moles of Na that reacts, 2 moles of NaCl are produced according to the balanced equation.
Therefore the number of moles of Na = number of moles of NaCl
n=0.36 mol
We can now find the mass of NaCl produced.
m=n x M
m=0.36 mol x 58.44 g/mol
m = 21.09 g