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

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Methyl palmitate, C17H34O2, is a component of one type of biochemical fuel. It is a liquid at room temperature. The molar enthalpy of combustion of methyl palmitate ... show full transcript

Worked Solution & Example Answer:Methyl palmitate, C17H34O2, is a component of one type of biochemical fuel - VCE - SSCE Chemistry - Question 4 - 2009 - Paper 1

Step 1

Calculate the calibration factor of the calorimeter:

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Answer

To calculate the calibration factor (CF), we use the formula:

CF=QΔTCF = \frac{Q}{\Delta T}

where Q is the energy supplied to the calorimeter, which can be calculated using:

Q=V×I×tQ = V \times I \times t

Here, V = 5.61 V, I = 4.40 A, and t = 240 s. Thus,

Q=5.61×4.40×240=5.61×4.40×240=4.440×103 JQ = 5.61 \times 4.40 \times 240 = 5.61 \times 4.40 \times 240 = 4.440 \times 10^3 \text{ J}

The temperature rise is 1.75°C, therefore the calibration factor becomes:

CF=4.440×1031.75=2.537×103 J °C−1extor2.54×103extJ°C−1CF = \frac{4.440 \times 10^3}{1.75} = 2.537 \times 10^3 \text{ J °C}^{-1} ext{ or } 2.54 \times 10^3 ext{ J °C}^{-1}

Step 2

Calculate the amount of energy absorbed by the calorimeter:

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Answer

Using the calibration factor calculated above:

Q=CF×ΔT=2.537×103×6.19=15664.83 J=15.66483extkJQ = CF \times \Delta T = 2.537 \times 10^3 \times 6.19 = 15664.83 \text{ J} = 15.66483 ext{ kJ}

Step 3

Calculate the amount of energy released by the combustion of 1.00 mol of methyl palmitate:

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The molar mass of methyl palmitate is 270 g mol−1. We first find the moles burned:

Moles=0.529g270g/mol=0.00196mol\text{Moles} = \frac{0.529 g}{270 g/mol} = 0.00196 mol

Using the energy released by the combustion:

Energy=15.66483extkJ0.00196extmol≈7982.4extkJmol−1\text{Energy} = \frac{15.66483 ext{ kJ}}{0.00196 ext{ mol}} \approx 7982.4 ext{ kJ mol}^{-1}

Step 4

Write the value of ΔH for this reaction, in kJ mol−1:

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Answer

From the balanced equation, we can determine that the enthalpy change ΔH is associated with the combustion of one mole. We can say that the value of ΔH will be:

ΔH=−7982.4extkJmol−1\Delta H = -7982.4 ext{ kJ mol}^{-1}

Step 5

Name one biochemical fuel and the raw material used in its production:

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Answer

One biochemical fuel is ethanol, which is produced from plant material such as sugar cane or corn.

Step 6

Identify one disadvantage or limitation of this biochemical fuel for the large-scale generation of electricity:

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One limitation of biochemical fuels like ethanol is that they require large amounts of agricultural land, which can compete with food production.

Step 7

State one advantage of using nuclear fission:

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Answer

An advantage of using nuclear fission is that it generates a large amount of energy from a small mass of fuel compared to fossil fuels.

Step 8

State one disadvantage of using nuclear fission:

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Answer

One disadvantage of using nuclear fission is the generation of radioactive waste, which poses environmental hazards and long-term storage concerns.

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