Sunday 15 September 2013

Topic 1.5: Solutions

1.5.1 Distinguish between the terms solute, solvent, solution and concentration (g dm^-3 and mol dm^-3)

Solutions are a mixture between two components, the less abundant component is the solute and the more abundant is the solvent.

Solute can be solid, liquid or gas.

Solvent is generally a liquid.

Salt water is a solution with salt as the solute and water as the solvent.

They are called aqueous solutions and are given the state symbol (aq).


Concentration has two units, either g dm^-3 or mol dm^-3

Concentration = Mass of solute / Volume of solvent

Concentration = Moles of solute / Volume of solvent

g dm^-3 = mol dm^-3 x molar mass

1.5.2 Solve problems involving concentration, amount of solute and volume of solute.

This equation will be least likely to be a question on its own. However it is used in a lot of different questions to test your basic knowledge.

Examiner's Tip : In Paper 1 you can find the best solution with less precise relative atomic mass values. This makes the calculation easier and saves time. For papers 2 and 3 estimate the answer before you use a calculator. This will help spot careless mistakes.

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