Solvents are used to dissolve, extract, or suspend other substances, without altering the chemical composition of either the solvents or the materials they interact with. Solvents are also used  to bring reactants together at appropriate concentrations and facilitate efficient mixing and stirring during reactions. Solvents are also crucial for energy control. Endothermic reactions can be facilitated by heating the solution. In exothermic reactions, solvents act as a heat sink to prevent uncontrolled reactions.