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Since the start of the industrial age, most of the energy used by humans has come from the burning of coal and oil - VCE - SSCE Chemistry - Question 9 - 2008 - Paper 1

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Since the start of the industrial age, most of the energy used by humans has come from the burning of coal and oil. In that time the amount of CO₂ in the air has inc... show full transcript

Worked Solution & Example Answer:Since the start of the industrial age, most of the energy used by humans has come from the burning of coal and oil - VCE - SSCE Chemistry - Question 9 - 2008 - Paper 1

Step 1

a. Calculate the additional mass of CO₂

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Answer

To find the additional mass of CO₂ added to the atmosphere, we first calculate the change in percentage of CO₂:

Δ%=0.58%−0.42%=0.16%\Delta\% = 0.58\% - 0.42\% = 0.16\%

Next, we convert this percentage into a mass using the total mass of the atmosphere:

m(CO2)=(0.16100)×5.15×1018 kg=8.24×1015 kgm(CO_2) = \left(\frac{0.16}{100}\right) \times 5.15 \times 10^{18} \text{ kg} = 8.24 \times 10^{15} \text{ kg}

Therefore, the additional mass of CO₂ in the atmosphere is approximately 8.24×10158.24 \times 10^{15} kg.

Step 2

b. Calculate the total amount of energy from burning coal

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Answer

Given that half of the additional CO₂ comes from burning coal:

n(CO2)=8.24×1015 kg44 g mol−1×1000 g1 kg=4.1×1016 moln(CO_2) = \frac{8.24 \times 10^{15} \text{ kg}}{44 \text{ g mol}^{-1}} \times \frac{1000 \text{ g}}{1 \text{ kg}} = 4.1 \times 10^{16} \text{ mol}

Now, we calculate the total energy produced by burning this coal:

Energy=n(CO2)×ΔH=4.1×1016 mol×(−394 kJ mol−1)=−1.62×1019 kJ\text{Energy} = n(CO_2) \times \Delta H = 4.1 \times 10^{16} \text{ mol} \times (−394 \text{ kJ mol}^{-1}) = −1.62 \times 10^{19} \text{ kJ}

Thus, the total amount of energy produced is approximately 1.62×10191.62 \times 10^{19} kJ.

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