A handbook gives the heat of combustion of liquid carbon disulfide as -3.42 kcal/g of the liquid. Write the equation representing the combustion of 1 mol of carbon disufide and the accompanying ΔH value. (hint: the sulfur containing combustion product is sulfur dioxide).
-3.42 kcal/g x (76g/mol) = approx -260 kcal/mol
CS2 + 3O2 ==> CO2 + 2SO2 + 260 kcal/mol
To determine the equation representing the combustion of 1 mol of carbon disulfide (CS2) and the accompanying ΔH value, follow these steps:
Step 1: Write the balanced equation for the combustion of CS2:
CS2 + 3O2 → CO2 + 2SO2
Step 2: Calculate the molar mass of CS2:
Carbon (C) has a molar mass of 12.01 g/mol.
Sulfur (S) has a molar mass of 32.07 g/mol.
Since CS2 has one carbon and two sulfur atoms, the molar mass of CS2 is:
Molar mass of carbon = 12.01 g/mol
Molar mass of sulfur = 32.07 g/mol
Molar mass of CS2 = (1 × 12.01 g/mol) + (2 × 32.07 g/mol) = 76.15 g/mol
Step 3: Calculate the heat of combustion per mole of CS2:
Given: Heat of combustion of CS2 = -3.42 kcal/g
To calculate the heat of combustion per mole, convert kcal to kcal/mol by multiplying by the molar mass of CS2:
Heat of combustion per mole = -3.42 kcal/g × (1 kcal/1,000 cal) × (1 mol/76.15 g) = -0.000045 mol/cal
Therefore, the equation representing the combustion of 1 mol of carbon disulfide (CS2) is:
CS2 + 3O2 → CO2 + 2SO2
And the accompanying ΔH value is -0.000045 mol/cal.