Sulphuric acid is a highly corrosive and reactive substance, so it is important to handle it with caution. When mixing sulphuric acid, it is important to slowly add the acid to water, rather than the other way around, to avoid a violent reaction. The addition of sulphuric acid to water can cause the mixture to foam, due to the release of heat and gas. The amount of foaming will depend on the concentration of the acid and the amount of water used. To minimize foaming, it is best to use a dilute acid solution and to add the acid slowly and carefully.