Question 4 Methyl palmitate, C₁₇H₃₄O₂, is a component of one type of biochemical fuel - VCE - SSCE Chemistry - Question 4 - 2009 - Paper 1

The energy absorbed by the calorimeter can be determined using:

$Q = CF \times \Delta T$

Where:

• ( \Delta T = 6.19°C ) Using the previously calculated calibration factor:

$Q = 0.394 \times 6.19 = 2.44026 \text{ J}$. Converting this to kJ gives: $Q = \frac{2.44026}{1000} = 0.00244 kJ$.

To find the energy released for 1 mol of methyl palmitate, we first find energy per gram:

From the absorbed energy calculation, we have:

• Energy per gram = ( \frac{0.00244}{0.529} \approx 0.00461 kJ/g ).

Then, convert this to kJ for 1 mol:

• Since the molar mass of methyl palmitate = 270 g/mol:

Energy released for 1 mol: $0.00461 \text{ kJ/g} \times 270 \text{ g} = 1.2437 kJ.$

The balanced equation for the combustion of methyl palmitate is:

$2C_{17}H_{34}O_{2}(l) + 490O_{2}(g) → 34CO_{2}(g) + 34H_{2}O(l)$.

From the previous calculations, we can derive the value of ΔH (enthalpy change) for the reaction as the calculated energy for 2 moles, given that the combustion of 1 mol corresponds to: $ΔH ≈ -1.2437 kJ$. To express it per mole of methyl palmitate, divide by 2: $ΔH ≈ -0.62185 kJ/mol$.

Biochemical fuel: Bioethanol.

Raw material used in its production: Sugarcane.

One disadvantage of biochemical fuels is that they may compete with food crops for land, potentially leading to food shortages.

One advantage of using nuclear fission is that it produces a large amount of energy from a small mass of fuel, reducing the volume of fuel needed.

One disadvantage of using nuclear fission is the potential risks associated with radioactive waste and the need for safe disposal methods.