Final answer:
The volume of H2 gas produced when an excess of sodium reacts with 100 ml of 0.8 M HCl at STP will be 896 mL.
Step-by-step explanation:
The volume of H2 gas produced when an excess of sodium (Na) reacts with 100 ml of 0.8 M HCl can be calculated using stoichiometry. The balanced chemical equation for the reaction is:
2 Na (s) + 2 HCl (aq) → 2 NaCl (aq) + H2 (g)
First, we must determine the number of moles of HCl in the solution:
0.1 L × 0.8 mol/L = 0.08 mol HCl
Since the reaction ratio between Na and HCl is 2:2, the same amount of HCl moles will produce half the number of moles of H2 because of the 2:1 ratio in the reaction for HCl to H2. Therefore, 0.08 mol of HCl will produce 0.04 mol of H2 gas.
At STP, 1 mole of gas occupies 22.4 liters, so 0.04 mol will occupy:
0.04 mol × 22.4 L/mol = 0.896 L of H2
So, the volume of H2 gas produced at STP will be 896 mL.