Chemistry 9701 · AS & A Level · An introduction to AS Level organic chemistry

An introduction to AS Level organic chemistry — practice question

Carbon dioxide, $\text{CO}_2$, contributes about $0.040\%$ to Earth’s atmosphere. It comes from animal respiration and from the burning of fossil fuels. During animal respiration, oxygen reacts with a carbohydrate such as glucose to produce water, carbon dioxide and energy. A typical person’s daily food intake may be treated as the same as $1.20\,\text{kg}$ of glucose, $\text{C}_6\text{H}_{12}\text{O}_6$. All numerical answers in this question should be given to three significant figures.
(a(i))

Construct a balanced equation for the complete oxidation of glucose.

(a(ii))

Use your equation to calculate the number of moles of $\text{CO}_2$ made by one person in one day from $1.20\,\text{kg}$ of glucose.

(a(iii))[5]

On the date this question was set, the world population was estimated as $6.82 \times 10^9$. Calculate the total mass of $\text{CO}_2$ generated by this many people in one day. Give your answer in tonnes. [$1\,\text{tonne} = 1.00 \times 10^6\,\text{g}$]

(b(i))

Construct a balanced equation for the complete combustion of octane, $\text{C}_8\text{H}_{18}$.

(b(ii))

The density of octane is $0.700\,\text{g cm}^{-3}$. Calculate the amount, in moles, of octane contained in $4.00\,\text{dm}^3$ of octane.

(b(iii))[5]

Calculate the mass of $\text{CO}_2$ formed when the fuel-efficient car travels a distance of $100\,\text{km}$.

(c)[2]

Calculate how many kilometres the same fuel-efficient car would need to travel to make as much $\text{CO}_2$ as the respiration of $6.82 \times 10^9$ people in one day. Use your answer to a(ii).

(d)[2]

Carbon dioxide is one of several gases linked with global warming. When fossil fuels such as octane burn in a car engine, additional atmospheric pollutants are also formed. Give the formula of one atmospheric pollutant that can be produced in a car engine, other than $\text{CO}_2$, and state how this pollutant harms the environment.

Worked solution & mark scheme

This 14-mark question has a full step-by-step worked solution and mark scheme. One marking point: Balanced equation that is correct: $\mathrm{C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O}$

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