Answer to Question #275445 in General Chemistry for Michael

Question

Iron reacts with hydrochloric acid to produce iron (II) chloride and hydrogen gas:

Fe_(s) + HCl_(aq) -----> FeCl₂ + H_{2 (g)}

The H₂ gas from the reaction of 300.0 g of iron with 300.0 g hydrochloric acid is collected in a 2000.mL flask at 20.00°C. What is the pressure of H₂ gas in this flask in bars? (1 atm = 1.01325 bars)

Answer 1

Balanced chemical equation:

Fe(s) + 2HCl(aq) → FeCl₂(aq) + H₂(g)

According to the equation above: n(Fe) = n(H₂)

The molar mass of Fe is 55.845 g/mol.

Therefore,

(2.2 g Fe) × (1 mol Fe / 55.845 g Fe) = 0.0394 mol Fe

n(H₂) = n(Fe) = 0.0394 mol

The Ideal Gas equation can be used.

The Ideal Gas equation can be expressed as: PV = nRT

P = unknown

V = 10.0 L

n = 0.0394 mol

R = 0.0821 atm L mol^-1 K^-1

T = 25˚C + 273 = 298 K

Thus,

P = nRT / V

P = (0.0394 mol × 0.0821 atm L mol^-1 K^-1 × 298 K) / (10.0 L) = 0.0964 atm

P = 0.0964 atm

Answer: 0.0964 atm is the pressure of H₂ gas in this flask.