State what the term relative formula mass means.
$\text{F}_2$ and $\text{HCl}$ are both covalent molecules. Suggest why the boiling point of HCl is higher than that of $\text{F}_2$.
Explain why $\text{CaF}_2$ has a very high boiling point.
$\text{CaF}_2\text{(aq)}$ can be made by the reaction of calcium carbonate with hydrofluoric acid, $\text{HF(aq)}$. Write an equation for this reaction. Include state symbols.
Complete the electronic configuration of a chloride ion: $1s^2\ ...$
When $\text{Cl}_2$ is passed over hot iron, $\text{FeCl}_3$ is formed. However, when $\text{I}_2\text{(g)}$ is passed over hot iron, the following reaction occurs: $\text{Fe(s)} + \text{I}_2\text{(g)} \rightarrow \text{FeI}_2\text{(s)}$. State what you would observe during the reaction between Fe and $\text{I}_2$. Explain why $\text{FeI}_2\text{(s)}$ is formed rather than $\text{FeI}_3\text{(s)}$.
$\text{FeI}_2$ is soluble in water. A student carries out a chemical test to confirm that a solution of $\text{FeI}_2$ contains aqueous iodide ions, $\text{I}^-\text{(aq)}$. The student adds a single reagent and a precipitate forms. Identify the reagent the student uses. State the colour of the precipitate that forms.
Compounds containing $\text{I}^-$ are often contaminated by bromide ions, $\text{Br}^-$. Identify a further reagent that the student could use to show that the precipitate formed in (iii) contained iodide ions.
Draw a ‘dot-and-cross’ diagram to represent the bonding in a molecule of HOF. Show the outer shell electrons only.
HOF can be made by the reaction of $\text{F}_2$ with ice at $-40^{\circ}\text{C}$. The reaction is similar to the reaction of $\text{Cl}_2$ with cold water. Suggest an equation for the reaction of $\text{F}_2$ with ice.
HOF is an unstable compound and breaks down to form HF and $\text{O}_2$. $\text{HOF} \rightarrow \text{HF} + \frac{1}{2}\text{O}_2 \ \ \Delta H = -139\,\text{kJ mol}^{-1}$. Draw a fully labelled reaction pathway diagram on the axes provided to show the decomposition of HOF into HF and $\text{O}_2$.
Pure HF is a colourless liquid at $273\,\text{K}$. The liquid contains HF molecules with strong hydrogen bonds between them. Draw a fully labelled diagram to suggest how a hydrogen bond can form between two HF molecules.
Interhalogen compounds, such as BrCl or $\text{IF}_5$, contain two or more different halogen atoms joined by covalent bonds. D is an interhalogen compound containing only chlorine and fluorine. At $0\,^{\circ}\text{C}$ and $101325\,\text{Pa}$, $1\,\text{dm}^3$ of D has a mass of $4.13\,\text{g}$. Use the general gas equation to calculate the relative molecular mass, $M_r$, of D.
Use your answer to (i) to determine the molecular formula of D. If you were unable to calculate the $M_r$ in (i), assume that the $M_r$ is $130.5$. This is not the correct value.