Give the complete electronic configuration of $\text{Fe}^{2+}$.
Calculate the oxidation number of sulfur in the $\text{S}_2^{2-}$ ion. Assume that each sulfur atom in the ion has the same oxidation number.
Describe the metallic bonding present in gold.
The sulfur dioxide produced during roasting would lead to environmental effects if it were released into the atmosphere. State and explain one of these environmental effects.
Complete the equation to represent the roasting of iron pyrite in oxygen. $4\text{FeS}_2 + \; \ldots \; \rightarrow 2\text{Fe}_2\text{O}_3 + \; \ldots$
A sample of impure iron pyrite was roasted in oxygen, and the composition of the solid product mixture is shown. Calculate the mass of $\text{FeS}_2$ present in the impure iron pyrite sample. Assume that all of the $\text{FeS}_2$ was changed into $\text{Fe}_2\text{O}_3$ during roasting. $(M_r:\; \text{FeS}_2 = 120.0; \; \text{Fe}_2\text{O}_3 = 159.6)$
Use your answer to (iii) to calculate the percentage by mass of gold in this sample of impure iron pyrite. Assume that gold is the only impurity present in this sample of impure iron pyrite. Give your answer to two significant figures. (If you were unable to calculate an answer to (iii), use $55.00\,\text{g}$ as the mass of $\text{FeS}_2$ in this calculation. This is not the correct answer.)