The table gives the heat of combustion in kJ g⁻¹ for a number of different fuels. | Fuel | Heat of combustion (kJ g⁻¹) | |-------------|-------------------------------| | Methanol | 22.7 | | Ethanol | 29.6 | | Propanol | 33.6 | | Petrol (octane) | 47.8 | The heat of combustion in kJ mol⁻¹ for one of the fuels was calculated as 2016 kJ mol⁻¹. What was the fuel? (A) Methanol (B) Ethanol (C) Propanol (D) Petrol

SSCE HSC Chemistry Alcohols: The table gives the heat of comb

The table gives the heat of combustion in kJ g⁻¹ for a number of different fuels - HSC - SSCE Chemistry - Question 6 - 2003 - Paper 1

Question 6

The table gives the heat of combustion in kJ g⁻¹ for a number of different fuels. | Fuel | Heat of combustion (kJ g⁻¹) | |-------------|---------------------... show full transcript

Worked Solution & Example Answer:The table gives the heat of combustion in kJ g⁻¹ for a number of different fuels - HSC - SSCE Chemistry - Question 6 - 2003 - Paper 1

Step 1

Identify the fuel with heat of combustion that corresponds to 2016 kJ mol⁻¹

96%

114 rated

Answer

To calculate the heat of combustion in kJ mol⁻¹ for each fuel, we need to multiply the heat of combustion in kJ g⁻¹ by the molar mass of the respective fuel:

Molar Mass Calculation:
- Methanol (CH₃OH): 12.01 + 3(1.008) + 16.00 = 32.04 g/mol
- Ethanol (C₂H₅OH): 2(12.01) + 6(1.008) + 16.00 = 46.08 g/mol
- Propanol (C₃H₇OH): 3(12.01) + 8(1.008) + 16.00 = 60.10 g/mol
- Petrol (C₈H₁₈): 8(12.01) + 18(1.008) = 114.23 g/mol
Heat of Combustion Calculation for Each Fuel:
- Methanol: $22.7 ext{ kJ g}^{-1} imes 32.04 ext{ g/mol} = 727.0588 ext{ kJ mol}^{-1}$
- Ethanol: $29.6 ext{ kJ g}^{-1} imes 46.08 ext{ g/mol} = 1361.0048 ext{ kJ mol}^{-1}$
- Propanol: $33.6 ext{ kJ g}^{-1} imes 60.10 ext{ g/mol} = 2016.36 ext{ kJ mol}^{-1}$
- Petrol: $47.8 ext{ kJ g}^{-1} imes 114.23 ext{ g/mol} = 5460.4586 ext{ kJ mol}^{-1}$

From this calculation, Propanol yields an approximate value of 2016 kJ mol⁻¹.

Step 2

Select the correct answer from the options

99%

104 rated

Answer

The correct answer is (C) Propanol, as it matches the calculated heat of combustion of 2016 kJ mol⁻¹.

The table gives the heat of combustion in kJ g⁻¹ for a number of different fuels - HSC - SSCE Chemistry - Question 6 - 2003 - Paper 1

Worked Solution & Example Answer:The table gives the heat of combustion in kJ g⁻¹ for a number of different fuels - HSC - SSCE Chemistry - Question 6 - 2003 - Paper 1

Identify the fuel with heat of combustion that corresponds to 2016 kJ mol⁻¹

Select the correct answer from the options

Join the SSCE students using SimpleStudy...