Question 53
Making zinc sulfate: use about 50 cm³ dilute sulfuric acid in a 250 cm³ beaker and add 1–5 g zinc. After fizzing stops, transfer the solution to an evaporating basin. Heat very gently until crystals begin at the edge, then stop heating and leave for a few days. Use safety glasses, tongs and a heatproof mat; the solution can spit and burn. Which is the better way to produce large crystals: heating until very little liquid is left, or leaving it to evaporate slowly?
