Question

Excess HCl is added to 234 g of Na2S solution as shown by the equation below:

Na2S(aq) + 2HCl(aq) →2NaCl(aq) + H2S(g)
How many liters of H2S gas are produced at standard temperature and pressure (STP)? The molar mass of Na2S is 78 g.

Answer 1

67 L

Step-by-step explanation:

Step 1: Write the balanced equation

Na₂S(aq) + 2 HCl(aq) → 2 NaCl(aq) + H₂S(g)

Step 2: Calculate the moles corresponding to 234 g of Na₂S

The molar mass of Na₂S is 78 g/mol.

234 g × 1 mol/78 g = 3.0 mol

Step 3: Calculate the moles of H₂S produced from 3.0 moles of Na₂S

The molar ratio of Na₂S to H₂S is 1:1. The moles of H₂S formed are 1/1 × 3.0 mol = 3.0 mol.

Step 4: Calculate the volume occupied by 3.0 moles of H₂S at STP

At STP, 1 mole of H₂S occupies 22.4 L.

3.0 L × 22.4 L/1 mol = 67 L