### KS3 Physics

Energy
Motion and Forces
Waves
Electricity and Electromagnetism
Matter
Space Physics

# Dissolving

To understand dissolving, it is important to know what a solvent, solute and solution are.

• Solute – The substance that dissolves to form a solution
• Solvent – A substance that can dissolve other substances to form a solution
• Solution – A mixture of one or two solutes that are dissolved in a solvent

During dissolving, solvent and solute particles collide. The solvent particles slowly move and surround the solute particles until the solute particles are evenly spread throughout the solvent.

An example of dissolving is when salt is stirred into water, as the salt dissolves in the water.

Remember:

• The substance that dissolves is the solute
• The substance that the solute dissolves in is called the solvent

This means that in a saltwater solution, the salt is the solute and the water is the solvent. The solute and solvent are mixed completely.

There is a limit to how much solute will dissolve in a particular volume of solvent. When no more solute dissolves, it becomes a saturated solution.

## Conservation of Mass

Just because the solute dissolves does not mean it disappears. For example, if 1 g of salt dissolves in 50 g of water, then the mass of the saltwater solution is (1 + 50) = 51 g.

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