Standard solutions

'Preparing a Primary Standard Solution'

A primary standard is one that:


 * Is available in a highly pure state.
 * Is stable in air.
 * Is readiily soluble in water.
 * Has a high relative formula mass.
 * Will react rapidly when in solution during volumetric analysis.

The recipe:


 * 1) Work out how much you want (volume) and select the appropriate glassware!
 * 2) Wash out the glassware carefully.
 * 3) Work out how much solid you require.
 * 4) Weigh a clean and empty weighing bottle.
 * 5) Weigh out your solid using a clean spatula on a balance which will weight to 0.01g.
 * 6) Transfer the solid from your weighing bottle into a clean beaker.
 * 7) Either wash out any remaining solids into the beaker, using distilled water, or re-weigh the weighing bottle and adjust the mass used in your laboratory book for the solid that was not transferred.
 * 8) Use a glass stirring rod to gently break up any crystals to a smaller size.
 * 9) Dissolve the solid in a mixture of about 80% of your final required volume.
 * 10) Decant the liquid into a volumetric flask.
 * 11) Rinse out the beaker with a little more solvent and add the washings to the flask (REPEAT).
 * 12) Top up the volume with distilled water from a dropping pipette until the bottom of the meniscus is level with the graduation.
 * 13) Place the stopper in the volumetric and invert several times to ensure complete mixing and a homogeneous solution.
 * 14) Calculate the molarity (concentration) of the solution.
 * 15) Transfer your solution to a clean bottle.
 * 16) Label the solution with your name, date, name of solution and molarity.