Define what is meant by mole.
10 cm$^3$ of a gaseous hydrocarbon, $\mathrm{C}_x\mathrm{H}_y$, was mixed with 100 cm$^3$ of oxygen gas, in excess. The gas mixture had a final volume of 95 cm$^3$. Concentrated, aqueous sodium hydroxide was then used on the mixture to absorb the carbon dioxide present. The gas volume then fell to 75 cm$^3$. Every gas volume was measured at 298 K and 100 kPa.
Write an equation for the reaction of sodium hydroxide with carbon dioxide.
Calculate the carbon dioxide volume produced by combustion of the hydrocarbon.
Calculate the volume of oxygen consumed in the reaction with the hydrocarbon.
Use your answers to (b)(ii) and (b)(iii), together with the initial hydrocarbon volume, to balance the equation below: $\mathrm{C}_x\mathrm{H}_y + \dots \mathrm{O}_2 \rightarrow \dots \mathrm{CO}_2 + z\mathrm{H}_2\mathrm{O}$.
Deduce the values of $x$, $y$ and $z$ in the equation in (iv).
Another hydrocarbon, $W$, with the formula $\mathrm{C}_4\mathrm{H}_8$, reacts with hydrogen bromide, HBr, to give two products $X$ and $Y$. $X$ and $Y$ are structural isomers of molecular formula $\mathrm{C}_4\mathrm{H}_9\mathrm{Br}$. Reaction of $X$ with aqueous alkali produces an alcohol, $Z$, that has no reaction with acidified dichromate(VI).
Give the structures and names of compounds $W$, $X$, $Y$ and $Z$.
When $W$ reacts with hydrogen bromide, more $X$ than $Y$ is formed. Explain why.