Write down what you would see, and write equations for the reactions that occur, when silicon(IV) chloride and phosphorus(V) chloride are mixed separately with water. silicon(IV) chloride phosphorus(V) chloride
Iron(III) chloride, $\text{FeCl}_3$, is used to remove unwanted copper from printed circuit boards (PCBs) by the reaction below. $\text{2FeCl}_3(aq) + \text{Cu}(s) \rightarrow \text{2FeCl}_2(aq) + \text{CuCl}_2(aq)$ A solution in which $\text{Fe}^{3+}(aq)$ was initially $1.50\ \text{mol dm}^{-3}$ was reused several times to dissolve copper from the PCBs, and was then analysed by titration as follows. A $2.50\ \text{cm}^3$ portion of the partly used solution was acidified and titrated with $0.0200\ \text{mol dm}^{-3}$ $\text{KMnO}_4$. This changes any $\text{FeCl}_2$ present back into $\text{FeCl}_3$. It was found that $15.0\ \text{cm}^3$ of $\text{KMnO}_4(aq)$ was needed to reach the end point. i) Construct an ionic equation for the reaction between $\text{Fe}^{2+}$ and $\text{MnO}_4^- $ in acid solution. ii) State here the $\text{Fe}^{2+} : \text{MnO}_4^-$ ratio from your equation in (i). iii) Calculate the number of moles of $\text{MnO}_4^-$ used in the titration. iv) Calculate the number of moles of $\text{Fe}^{2+}$ in $2.50\ \text{cm}^3$ of the partly used solution. v) Calculate the $[\text{Fe}^{2+}]$ in the partly used solution. vi) Calculate the mass of copper that could still be dissolved by $100\ \text{cm}^3$ of the partly used solution.
When $\text{SiCl}_4$ vapour is passed over $\text{Si}$ at red heat, $\text{Si}_2\text{Cl}_6$ is formed. $\text{Si}_2\text{Cl}_6$ contains a Si-Si bond. The reaction of $\text{Si}_2\text{Cl}_6$ and $\text{Cl}_2$ re-forms $\text{SiCl}_4$. $\text{Si}_2\text{Cl}_6(g) + \text{Cl}_2(g) \rightarrow 2\text{SiCl}_4(g)$ Use bond energy data from the Data Booklet to calculate $\Delta H^\circ$ for this reaction.
Calcium forms three calcium silicides, $\text{Ca}_2\text{Si}$, $\text{CaSi}$ and $\text{CaSi}_2$. The first of these reacts with water as shown below. $\ldots\text{Ca}_2\text{Si} + \ldots\text{H}_2\text{O} \rightarrow \ldots\text{Ca(OH)}_2 + \ldots\text{SiO}_2 + \ldots\text{H}_2$ i) Balance this equation. The use of oxidation numbers may help you. ii) During this reaction, state which element(s) have been oxidised and which element(s) have been reduced.