Question

calculate the volume of CO2(g) formed by the complete combustion of 125.0 g of C5H12(g) (M.Wt.=72 g/mol) at 1.00 atm pressure and 0 degrees celsius.

Answer 1

Step 1: Explanation

The ideal gas law is the equation of state of a hypothetical ideal gas. It gives good approximation of the behavior of many gases under many conditions.

We know the ideal gas equation, PV = nRT

where, R=universal gas constant ( it may vary in unit like 0.08206 L-atm mol^-1 K^-1 )

T=Temperature ( Unit = Kelvin )

P=Pressure ( Unit= atm )

,V=Volume ( Unit=Litre )

,n=moles ( Unit = mol )

Step 2: Calculate the moles of carbon dioxide

we know, moles = mass given / molar mass

moles of pentane ( C₅H₁₂) = 125 g / 72 g/mol = 1.7361 mol

C₅H₁₂(l) + 8 O₂(g)⟶ 5 CO₂(g) + 6 H₂O(l)

From the equation we can see

1 moles of pentane produced 5 moles of carbon dioxide

so 1.7361 mol of pentane will produced  = ( 5 mol / 1 mol )  × 1.7361  mol = 8.681 mol of carbon dioxide

Step 3: calculate the volume of carbon dioxide

moles(n) = 8.681 mol

Pressure(P) = 1 atm and Temperature(T)= 0 °C = ( 0 +273 )K = 273 K

By using ideal gas equation

PV = nRT

=> V = nRT / P = ( 8.681 mol  × 0.08206 L.atm /mol.K × 273 K ) / 1 atm = 194.5 L

hence, the volume of carbon dioxide produced = 194.5  L