According to the chemical equation

2CuCl_2(s) + 4KI_(s) ---> 2CuCl_(s) + 4KCl_(s) + I_2(s)

a) how many grams of iodine are produced when 145 g of KI react with excess copper(II) chloride?

Answer

This problem is slightly different compared to the earlier problems. The most important change is the amount of starting material is given in grams and not moles. To solve this problem we must first convert the mass of potassium iodide to moles using the molar mass of potassium iodide. Then we can use the stoichiometric factor to convert from moles of potassium iodide to moles of iodine. This stoichiometric ratio is obtained from the balanced chemical equation. According to the balanced chemical equation four mol of potassium iodide react to form 1 mol of iodine. Potassium iodide and iodine always combine in this ratio according to this equation. After determining the moles of iodine we can convert moles to grams of iodine using the molar mass of iodine.