(a)[2]
Define what Le Chatelier’s principle means.
(b)[3]
Reaction 1 is the reversible reaction between yellow $\text{Fe}^{3+}(aq)$ and colourless $\text{SCN}^-(aq)$ to form red $\text{FeSCN}^{2+}(aq)$. The temperature of an equilibrium mixture at $20\,^{\circ}\text{C}$ is raised to $50\,^{\circ}\text{C}$. Deduce the changes that occur, if any, in the equilibrium mixture at $50\,^{\circ}\text{C}$ compared with $20\,^{\circ}\text{C}$: change in appearance; change in relative concentration of $\text{FeSCN}^{2+}(aq)$; change in value of the equilibrium constant, $K_c$.
(c(i))[2]
Calculate the initial amount, in mol, of $\text{Fe}^{3+}(aq)$ added to $\text{SCN}^-(aq)$ in order to make this mixture.
(c(ii))[2]
Calculate $K_c$ for reaction 1 and give its units. Show your working.