Preparation of a standard solution of sodium carbonate
Anhydrous sodium carbonate is a suitable chemical (primary standard) for the preparation of a standard solution. Standard Solutions are critical in chemistry because you need to have solutions with an EXACT known concentration and volume. Chemicals/Materials: solid sodium carbonate (Na2CO3) distilled water
Apparatus: 250cm3 volumetric flask 250cm3 beaker Glass stirring rod Weighting boat or aluminium foil Dropping pipette Electronic scales to 2 DP
Health and safety: Sodium carbonate powder may irritate the lungs if you breathe it in. Eye contact: Immediately flush the eye with water. If irritation persists, call for medical help. Skin contact: Wash off with water. Wear safety glasses. Procedure : Weight out about 1.5 g of sodium carbonate and place in a warm oven and leave to dry. (We do not do this – but WHY must you if you had time?) Accurately weight out 1.3g of sodium carbonate using the method of “weighing by difference”. Record the mass of Na2CO3 used to at least 2 decimal places. Weigh boat first, record value, then add Na2CO3, record value. The difference should be 1.3g. Operation Mass of weight boat + sodium carbonate Mass of weigh boat Mass of Na2CO3 Mass (g)
Transfer the weighed Na2CO3to a clean glass 250 cm3 beaker & add about 100 cm3 of distilled water. Use a clean glass stirring rod to mix the solution until all the sodium carbonate has dissolved. After dissolving, transfer the solution to a 250.00 cm3 volumetric flask. Carefully rinse the beaker and stirring rod and transfer all the washes into the volumetric flask. Take care not to overshoot the graduation mark of the flask. Make the volumetric flask up to approximately 1 cm below the mark on the neck using distilled water from a wash bottle and then using a dropping pipette make up to the mark.
BTEC Chemistry – Titration...