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

To find the mass of pentan-1-ol combusted, first determine the number of moles of pentan-1-ol that corresponds to the generated heat of 108 kJ.

1. Calculate the moles of pentan-1-ol: The molar heat of combustion is given as 2800 kJ/mol. Using the equation:

   $ext{Number of moles} = \frac{\text{Heat generated}}{\text{Molar heat of combustion}}$

   Substituting the values:

   $\text{Number of moles} = \frac{108 \text{ kJ}}{2800 \text{ kJ/mol}} = 0.03857 \text{ mol}$

2. Find the mass of pentan-1-ol: The molar mass of pentan-1-ol is approximately 88.15 g/mol. Using the relation:

   $ext{Mass} = \text{Number of moles} \times \text{Molar mass}$

   $ext{Mass} = 0.03857 \text{ mol} \times 88.15 \text{ g/mol} \approx 3.41 g$

3. Conclusion: The closest answer is (D) 3.40 g.