Assignmnetseller123
Preparing 250cm3 of 0.5 mol.dm-3 Sodium Carbonate solution
Standard solution: a solution containing a precisely known concentration of an element or
substance.
Method:
o Calculate the mass of sodium carbonate solid needed to produce 250 cm 3 of a 0.500 mol dm-3
solution. To do this you need to:
Calculate the Mr of Na2CO3 : (23 x 2) + 12 + (16 x 3) = 106
You know the wanted concentration is 0.5 mol/dm 3 so to find the mass needed use the
mass
equation Moles= 0.5 x 106 = 56g
mr
56/4 = 13.25
o Put a clean, dry weighing boat on a balance and reset to zero.
o Using a spatula, place into the boat 13.25g of sodium carbonate.
o Pour the contents of the weighing boat into a beaker ensuring that all of the powder is
transferred.
o Add approximately 100 cm3 of distilled water to the beaker containing the solid and use a glass
rod and stir the contents of the beaker until all of the sodium carbonate dissolves.
o Using a funnel, pour the contents of the beaker into a 250 cm3 volumetric flask then using the
wash bottle rinse the beaker and funnel into the same volumetric flask. Rinse the glass rod into
these washings.
o Make the volumetric flask up to the graduated mark by carefully adding distilled water from the
wash bottle. You will need to be careful so that you do not over-shoot the mark.
o Stopper the volumetric flask and shake it thoroughly to mix the contents of the flask.
Risk assessment :
Hazard Risk Action
glassware It can break and cut E.g. take extreme care when
your hand handling the beakers and volumetric
flasks
Sodium carbonate it can get into eyes E.g. wear goggles to protect eyes
Tripping you can fall over E.g. tuck the chairs under the tables
Preparing 250cm3 of 0.5 mol.dm-3 Sodium Carbonate solution
Standard solution: a solution containing a precisely known concentration of an element or
substance.
Method:
o Calculate the mass of sodium carbonate solid needed to produce 250 cm 3 of a 0.500 mol dm-3
solution. To do this you need to:
Calculate the Mr of Na2CO3 : (23 x 2) + 12 + (16 x 3) = 106
You know the wanted concentration is 0.5 mol/dm 3 so to find the mass needed use the
mass
equation Moles= 0.5 x 106 = 56g
mr
56/4 = 13.25
o Put a clean, dry weighing boat on a balance and reset to zero.
o Using a spatula, place into the boat 13.25g of sodium carbonate.
o Pour the contents of the weighing boat into a beaker ensuring that all of the powder is
transferred.
o Add approximately 100 cm3 of distilled water to the beaker containing the solid and use a glass
rod and stir the contents of the beaker until all of the sodium carbonate dissolves.
o Using a funnel, pour the contents of the beaker into a 250 cm3 volumetric flask then using the
wash bottle rinse the beaker and funnel into the same volumetric flask. Rinse the glass rod into
these washings.
o Make the volumetric flask up to the graduated mark by carefully adding distilled water from the
wash bottle. You will need to be careful so that you do not over-shoot the mark.
o Stopper the volumetric flask and shake it thoroughly to mix the contents of the flask.
Risk assessment :
Hazard Risk Action
glassware It can break and cut E.g. take extreme care when
your hand handling the beakers and volumetric
flasks
Sodium carbonate it can get into eyes E.g. wear goggles to protect eyes
Tripping you can fall over E.g. tuck the chairs under the tables
