1. Moles and solutions

2. Making a solution Solutions are made by dissolving a solid, the solute, in a liquid, the solvent.

3. The concentration of a solution… depends on how many moles of solute is dissolved in a given volume of water.

4. Equation of concentration Concentration = N o of moles Volume Units; moldm -3 (mol/dm 3 or M). NB not mol/dm -3 NB Volume must be converted from cm 3 to dm 3 by dividing by 1,000.

5. Calculating the concentration Eg; What is the concentration of a solution that is made up by dissolving 0.2 moles of sodium hydroxide in 250cm 3 of distilled water? First convert the volume into decimetres. 250 cm 3 = 250/1000 = 0.25 dm 3 Then substitute into the formula; C = n/v C = 0.2/0.25 = 0.8 moles dm -3.

6. Concentration Number of moles Volume C n V Think of the equation as a triangle

7. Concentration = Number of moles Volume C n V C = n / V Rearranging;

8. Concentration Number of moles = C n V n = CV XVolume Rearranging;

9. Calculating the number of moles in a solution. The equation C = n/v can be rearranged to give; Number of moles = concentration x volume. Eg; How many moles are there in 12.50 cm 3 of a 2 mol dm -3 solution? Convert the volume into decimetres. 12.50/1000 = 0.0125 dm 3 Substitute into the equation n = CV; n = 2 x 0.0125 = 0.025 moles.

10. Concentration Number of moles C n V V = n/C Volume = Rearranging;

11. Calculating the volume. The equation C = n/v can be rearranged to give; Volume = N o moles/ concentration. Eg; What volume of 2 mol dm -3 hydrochloric acid would contain 0.5 moles? V = n/c V = 0.5/2 = 0.25 dm 3 = 250cm 3.