Monday, 10 November 2014

Investigating how the concentration of Calcium ions present in samples of water affect the volume of water softener needed to soften the water.

Equipment List

250 cm3 Conical Flask & Bung
Measuring cylinder, 100cm3, 25cm3 & 10cm3.
1% Soap Solution
Hard Water
Distilled Water
Sodium Carbonate Solution (0.40 mol/dm3)
Stop Watch


1.     Measure 20cm3 of hard water (containing the calcium ions) and pour it into the conical flask.
2.     Measure out 80cm3 of distilled water and add it to the conical flask.
3.     Add 5cm3 soap solution to the water.
4.     Add 1cm3 of sodium carbonate solution (water softener), put on the bung and shake vigorously for 10 seconds.
5.     Leave the flask for 20 seconds and if there is still a lather then record the volume of sodium carbonate solution added. If not add another 1cm3 of sodium carbonate solution, shake for 10 seconds and leave for another 20 seconds. Repeat this process until you have a lather and record the volume of sodium carbonate added.
6.     Rinse out the flask thoroughly.
7.     Now measure out 40cm3 of hard water, add it to the conical flask and add 60cm3 of water to dilute it up to 100cm3 and repeat the experiment.
8.     Do this for 60cm3, 80cm3 and 100cm3 of hard water ensuring that enough distilled water is added to keep the total volume at 100cm3.

Volume of hard water (cm3)
Volume of distilled water (cm3)
Volume of sodium carbonate solution added (cm3)

Risk assessment
The soap solution is flammable to keep it away from naked flames.
The soapy water is very slippery so you must mop up any spills as soon as possible to avoid someone slipping over on it.

Monday, 3 November 2014

Measuring yeast activity vs temperature


Sugar (glucose for preference)
Water bath
Conical flask
bung and delivery tube
water trough
Measuring cylinders


Make up a solution of water and yeast, enough for five experiments (1.5 litre should be sufficient)
Swirl the solution and then measure 200ml into a conical flask.
Add 20g of sugar to the solution in the conical flask and swirl so it dissolves.
Place the conical flask into the water bath set to initial temperature of 20 degrees.
Place in the bung and delivery tube and run the delivery tube into the water trough.
Fill and upend the measuring cylinder over the end of the tube and start the stopclock.
Time how long it takes for 20ml of gas to be produced by the yeast.

Repeat the experiment at a temperature range of 20 degrees to 50 degrees in 5 degree intervals.

Water may be spilled so care should be taken and spills mopped up straight away. Any glass breakages should also be cleared up straight away using a dustpan and brush. At the upper end of the temperature range care should be taken when removing the conical flask from the waterbath to make sure it is not too hot to touch and move safely.