How many grams of sodium are required?

Question

How many grams of sodium are required to completely react with 19.2 L of Cl₂ gas at STP according to the following chemical reaction? Remember 1 mol of an ideal gas has a volume of 22.4 L at STP

2 Na(s) + Cl₂(g) → 2 NaCl(s)

Answer 1

Since at STP, moles of Cl2 would be simply 19.2L/22.4L = 0.857 mol, the balanced chemical equation is

2Na + Cl₂ —-> 2NaCl ; 0.857 mol Cl_{2/ 1} X 2 mole Na/ 1 mol Cl₂ X 23.0 g Na/ 1 mol Na = 39.4 g Na

Answer 2

Molar mass of CL2 is 70.9 g/mol, 19.2L Cl2 at STP is 19.2/22.4=0.857 mole, 0.857*70.9=60.77 g

molar mass of Na is 23 g/mol

In the reaction 2Na+Cl2=2NaCl, 2*23 g Na generates 70.9g Cl2, So needed Na mass for 60.77g H2 =60.77/70.9*2*23=39.43 g