The following reaction is done at stp:

c (s) + 2h2 (g) = ch4 (g)

if the reaction produces 145 liters of ch4, how many liters of h2 were consumed?

290.0 L.

Explanation:

it is clear that 1.0 mole of C reacts with 2.0 moles of H₂ to produce 1.0 mole of CH₄.

PV = nRT,

where, P is the pressure of the CH₄ gas produced in atm (P = 1.0 atm at STP).

V is the volume of the CH₄ gas produced in L (V = 145.0 L).

n is the no. of moles of the CH₄ gas produced in mol.

R is the general gas constant (R = 0.082 L.atm/mol.K).

T is the temperature of the CH₄ gas produced in K (T = 273.15 K at STP).

∴ n = PV/RT = (1.0 atm)(145.0 L)/(0.082 L.atm/mol.K)(273.15 K) = 6.47 mol.

Using cross multiplication:

2.0 moles of H₂ produce → 1.0 mole of CH₄, from the stichiometry.

??? mole of H₂ produce → 6.47 mole of CH₄.

∴ The no. of moles of H₂ consumed to produce 145.0 L CH₄ = (2.0)(6.47)/(1.0) = 12.94 mol.

Now, we can get the liters of H₂ consumed to produce 145.0 L CH₄:

∴ V = nRT/P = (12.94 mol)(0.082 L.atm/mol.K)(273.15 K)/(1.0 atm) = 290.0 L.

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