Chemistry 9701 · AS & A Level · Hydrocarbons

Hydrocarbons — practice question

Propane, $\text{C}_3\text{H}_8$, and butane, $\text{C}_4\text{H}_{10}$, are constituents of Liquefied Petroleum Gas (LPG), which is commonly burned as a domestic cooking and heating fuel.
(a(i))[1]

What class of compounds do these two hydrocarbons fall into?

(a(ii))[1]

Write a balanced equation for the complete combustion of butane.

(b(i))[1]

What is the chemical name of this black solid?

(b(ii))[1]

Write a balanced equation for its formation from butane.

(c)[2]

Propane and butane have different values of standard enthalpy change of combustion.\n\nDefine the term standard enthalpy change of combustion.

(d(i))[1]

Use the equation $pV = nRT$ to calculate the mass of propane used.

(d(ii))[2]

Use relevant data from the Data Booklet to calculate the amount of heat released in this experiment.

(d(iii))[2]

Use the data above and your answers to (i) and (ii) to calculate the energy produced by the burning of $1\ \text{mol}$ of propane.

(e(i))[2]

Suggest an explanation for the increase in boiling points from methane to butane.

(e(ii))[2]

The isomer of butane, 2-methylpropane, $(\text{CH}_3)_3\text{CH}$, has a boiling point of $261\ \text{K}$. Suggest an explanation for the difference between this value and that for butane in the table above.

Worked solution & mark scheme

This 15-mark question has a full step-by-step worked solution and mark scheme. One marking point: Alkanes or paraffins (not hydrocarbons)

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