Let's solve this step-by-step.
Given:
- Mass of propane combusted = 2.00 g
- Enthalpy change for combustion of 2.00 g propane = −102 kJ
- We want: Enthalpy change for combustion of 1 mole of propane (C₃H₈)
Step 1: Calculate the molar mass of propane (C₃H₈)
- Carbon (C) atomic mass ≈ 12.01 g/mol
- Hydrogen (H) atomic mass ≈ 1.008 g/mol
Molar mass of C₃H₈ = (3 × 12.01) + (8 × 1.008)
= 36.03 + 8.064
= 44.094 g/mol
Step 2: Calculate moles of propane in 2.00 g
moles=massmolar mass=2.00 g44.094 g/mol≈0.0454 mol\text{moles}=\frac{\text{mass}}{\text{molar mass}}=\frac{2.00\text{ g}}{44.094\text{ g/mol}}\approx 0.0454\text{ mol}moles=molar massmass=44.094 g/mol2.00 g≈0.0454 mol
Step 3: Calculate enthalpy change per mole
Given that −102 kJ is for 0.0454 mol, then for 1 mole:
ΔH=−102 kJ0.0454 mol≈−2248 kJ/mol\Delta H=\frac{-102\text{ kJ}}{0.0454\text{ mol}}\approx -2248\text{ kJ/mol}ΔH=0.0454 mol−102 kJ≈−2248 kJ/mol
Final answer:
The enthalpy change for the combustion of 1 mole of propane under the same conditions is approximately −2248 kJ/mol. If you want, I can also help you compare this with standard enthalpy values or explain the combustion reaction involved!