Chemistry 9701 · AS & A Level · Hydrocarbons

Hydrocarbons — practice question

Crude oil is a natural hydrocarbon resource that serves as a source of fuels.
(a(i))[1]

State the process by which long-chain hydrocarbons are split into shorter-chain hydrocarbons.

(a(ii))[1]

Give one reason why hydrocarbons with low $M_r$ are suitable to use as fuels.

(a(iii))[1]

When hydrocarbons undergo incomplete combustion, carbon monoxide, $\text{CO}$, can be released into the air. Write an equation showing the formation of $\text{CO}$ from the incomplete combustion of butene, $\text{C}_4\text{H}_8$.

(a(iv))[2]

Name an analytical technique that could be used to track the concentration of $\text{CO}$ in the atmosphere. Outline how this analytical technique may be used to track the concentration of $\text{CO}$.

(b(i))[2]

Write the equation for the complete combustion of thiophene, $\text{C}_4\text{H}_4\text{S(l)}$. Include state symbols in your response.

(b(ii))[2]

A student performs an experiment to find the enthalpy change of combustion of $\text{C}_4\text{H}_4\text{S(l)}$. Explain what is meant by the term enthalpy change of combustion.

(b(iii))[2]

Calculate the heat energy released, in J, by the reaction. Assume that $4.18\ \text{J}$ of heat energy changes the temperature of $1.0\ \text{cm}^3$ of water by $1.0^\circ\text{C}$. Assume that no heat is lost to the surroundings.

(b(iv))[2]

The student used $0.63\ \text{g}$ of $\text{C}_4\text{H}_4\text{S(l)}$ in the experiment. Calculate the enthalpy change of combustion of thiophene, $\Delta H_c(\text{C}_4\text{H}_4\text{S(l)})$. Include a sign in your response.

(c(iii))[2]

Calculate the heat energy released, in J, by the reaction. Assume that $4.18\,\text{J}$ of heat energy changes the temperature of $1.0\,\text{cm}^3$ of water by $1.0\,^\circ\text{C}$. Assume that no heat is lost to the surroundings.

(c(iv))[2]

The student used $0.63\,\text{g}$ of $\text{C}_4\text{H}_4\text{S}(l)$ in the experiment. Calculate the enthalpy change of combustion of thiophene, $\Delta H_c(\text{C}_4\text{H}_4\text{S}(l))$. Include a sign in your response.

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