SSCE HSC Chemistry Enthalpy: The molar heat of combustion of

The molar heat of combustion of pentan-1-ol is 2800 kJ mol⁻¹ - HSC - SSCE Chemistry - Question 17 - 2011 - Paper 1

Question 17

The molar heat of combustion of pentan-1-ol is 2800 kJ mol⁻¹. A quantity of pentan-1-ol was combusted, generating 108 kJ of heat. What mass of pentan-1-ol was combu... show full transcript

Worked Solution & Example Answer:The molar heat of combustion of pentan-1-ol is 2800 kJ mol⁻¹ - HSC - SSCE Chemistry - Question 17 - 2011 - Paper 1

Step 1

Calculate Moles of Pentan-1-ol Combusted

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Answer

To find the number of moles of pentan-1-ol that were combusted, we can use the formula:

$n = \frac{q}{\Delta H}$

where:

$n$ is the number of moles,
$q$ is the heat released (108 kJ),
$\Delta H$ is the molar heat of combustion (2800 kJ/mol).

Substituting the values, we have: $n = \frac{108\, \text{kJ}}{2800\, \text{kJ mol}^{-1}} = 0.03857\, \text{mol}$

Step 2

Calculate Mass of Pentan-1-ol

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Answer

Next, we need to find the mass of pentan-1-ol using the number of moles we've calculated.

The molar mass of pentan-1-ol (C₅H₁₂O) is approximately:

C: 12.01 g/mol × 5 = 60.05 g/mol
H: 1.008 g/mol × 12 = 12.096 g/mol
O: 16.00 g/mol × 1 = 16.00 g/mol
Total molar mass = 60.05 + 12.096 + 16.00 = 88.146 g/mol

Using the formula:

$\text{mass} = n \times \text{Molar Mass}$

we can substitute the values: $\text{mass} = 0.03857\, \text{mol} \times 88.146\, \text{g mol}^{-1} \approx 3.40\, \text{g}$

The molar heat of combustion of pentan-1-ol is 2800 kJ mol⁻¹ - HSC - SSCE Chemistry - Question 17 - 2011 - Paper 1

Worked Solution & Example Answer:The molar heat of combustion of pentan-1-ol is 2800 kJ mol⁻¹ - HSC - SSCE Chemistry - Question 17 - 2011 - Paper 1

Calculate Moles of Pentan-1-ol Combusted

Calculate Mass of Pentan-1-ol

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