Chemistry 9701 · AS & A Level · Hydrocarbons

Hydrocarbons — practice question

Carbon and silicon are both elements in Group 14.
(a(i))[2]

Describe the lattice arrangement in solid $\text{C}_{60}$.

(a(ii))[4]

$\text{C}_{60}$ sublimes (changes straight from solid to gas) at about $800\,\text{K}$. Diamond also sublimes, but only above $3800\,\text{K}$. Explain why $\text{C}_{60}$ and diamond sublime at such different temperatures.

(b(i))[1]

$\text{C}_{60}$ forms hydrocarbons with similar chemical properties to those of alkenes. One such hydrocarbon is $\text{C}_{60}\text{H}_{18}$. State what the term hydrocarbon means.

(b(ii))[2]

Describe a test to show the presence of double bonds between carbon atoms in $\text{C}_{60}\text{H}_{18}$. Give the result of the test.

(c(i))[1]

Name the type of reaction that occurred.

(c(ii))[1]

Calculate the amount, in moles, of $\text{C}_{60}$ that reacted.

(c(iii))[2]

Calculate the amount, in moles, of hydrogen gas that reacted with the $\text{C}_{60}$.

(c(iv))[2]

Use your answers from (ii) and (iii) to deduce the molecular formula of the hydrocarbon, $\text{C}_{60}\text{H}_{2x}$. If you could not work out the amount of hydrogen gas, take $0.00240\ \text{mol}$ of hydrogen gas as the value reacted. This is not the correct amount of hydrogen gas that reacted.

(d(i))[2]

State the type of bonding and structure shown by silicon.

(d(ii))[1]

When silicon reacts with magnesium, $\text{Mg}_2\text{Si}$ is formed. $\text{Mg}_2\text{Si}$ is believed to contain the $\text{Si}^{4-}$ ion. State the full electronic configuration of the $\text{Si}^{4-}$ ion.

(d(iii))[2]

Solid $\text{Mg}_2\text{Si}$ reacts with dilute hydrochloric acid to make gaseous $\text{SiH}_4$ and a solution of magnesium chloride. Write an equation for the reaction of solid $\text{Mg}_2\text{Si}$ with dilute hydrochloric acid. Include state symbols.

(d(iv))[1]

Predict the shape of the $\text{SiH}_4$ molecule.

(d(v))[1]

$\text{SiH}_4$ reacts spontaneously with oxygen to form a white solid and a colourless liquid that turns anhydrous copper(II) sulfate blue. No other products are made. Write an equation for the reaction of $\text{SiH}_4$ with oxygen. State symbols are not required.

Worked solution & mark scheme

This 22-mark question has a full step-by-step worked solution and mark scheme. One marking point: simple molecular lattice

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI