Concentration •How to make a standard solution of a known concentration. C

•Calculate the concentration of a solution. B

•Re-arrange equation to calculate mass/volume when given concentration and volume/mass. A

Starter

• Use white boards to answer recap quiz.

• Any analytical test must be carried out on a solution.• You only test a sample (small bit of it).• Dissolve the sample in a solution.• Aqueous means water• Non aqueous any thing but water. E.g. ethanol• Must follow a standard procedure.• Standard procedures are the safest, most effective and

most accurate.• A standard procedure is the same in a company,

nationally and internationally.• Standard procedures are always reliable • Standard proceedures for collection, storgae and

testing.

Concentration = mass of solute ÷ volume of solvent (g/dm3) (g) (dm3)

M

C vx

÷

Complete activity sheet

• AC7.15

Making a standard solution(This has a known concentration)

1. Work out how many g of solute you need by using equation.

2. Weigh out mass of solute.3. Add a small amount of distilled water and stir.4. Tip in to a volumetric flask, use a funnel5. Rinse the beaker, rod and funnel and add to flask.6. Top up to correct volume, ensure meniscus

reaches the line. 7. Stopper and mix a few times.8. Check meniscus.

Make a standard solution

• Make 250cm3 of 314g/dm3 of NaCl• To answer :• Why carry out steps 3-8?

Plenary

• Rate learning 1-4 (1 poor, 4 excellent)• Rate activities (as above)• Write 1 thing you really understand• Write 1 thing you still do not understand