Answer to Question #120316 in Inorganic Chemistry for aljoc

Question

Hydrogen gas is generated by the decomposition of water to fill a 1.1 kL weather balloon at 20°C and 100.0 kPa. What is the mass of hydrogen required?

Answer 1

P = 100.0 kPa

V = 1.1 kL = 1100 L

T = 20°C = 293 K

R = 8.314 kPa L mo^-1 K^-1

Solution:

The decomposition reaction of water:

2H₂O → 2H₂ + O₂

Ideal Gas Law can be used.

Ideal Gas Law can be expressed as: PV=nRT

To find the moles of H₂, solve the equation for n:

n = PV/RT

Moles of H₂ = n(H₂) = (100.0 kPa × 1100 L) / (8.314 kPa L mol^-1 K^-1 × 293 K) = 45.156 mol

Moles of H₂ = Mass of H₂ / Molar mass of H₂

The molar mass of H₂ is 2.016 g/mol.

Finally, the mass of H₂ is:

m(H₂) = n(H₂) × M(H₂) = (45.156 mol) × (2.016 g/mol) = 91.034 g = 91 g

The mass of H₂ is 91.0 g

Answer: 91 g is the mass of hydrogen required.