When mixing chemicals with water, what is the safest practice?

Adding chemicals to water is the safest practice because it minimizes the risk of violent reactions. When chemicals are added directly to water, the water acts as a heat sink, preventing the mixture from reaching a temperature that might trigger an explosion or violent reaction. This is particularly important for concentrated acids or other reactive substances, which can release heat rapidly when mixed with water.

If chemicals are added to water, the water surrounds the solid or liquid chemical, allowing it to dissolve or react in a controlled manner. This controlled introduction of chemicals helps to ensure that any exothermic reaction proceeds safely.

In contrast, adding water to chemicals can result in the water becoming trapped beneath the chemical, leading to localized heating and potential splattering. Mixing them equally in a separate container or adding them simultaneously could also create dangerous reactions, as these methods do not allow for proper control over the reaction process or the heat generated.