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

Method

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)
20
80
 
40
60
 
60
40
 
80
20
 
100
0
 










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

Equipment

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

Method

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.

Hazards
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.

Wednesday, 4 June 2014

Centre of mass & stability

Equipment

2 litre straight sided plastic drinks bottle with lid
Ruler
Protractor
Water
Wooden board with wooden lolly stick glued on

Method

Place the empty bottle on the wooden board so that the edge of the base buts up against the lolly stick so it does not slide.
Align the centre of the protractor with the edge of the board and slowly raise the opposite side so that the bottle starts to lean.
When the bottle falls read off the angle on the protractor. Repeat this at least twice more.
Add 5cm depth of water to the bottle using the ruler to measure.
Screw the lid on again tightly and repeat the tipping and recording of the topple angle.
Continue to add 5cm dept of water and repeat the tipping until the bottle is full.

Plot a graph of water height vs toppling angle. Why does it have this shape?

Risk assessment

Ensure lid is screwed on tightly when carrying out this experiment. Any spills should be mopped up straight away. As the bottle fills it will become heavier and could hurt feet if it rolls off the table, to reduce the chance of this happening carry out the experiment in the middle of the table and have a second person ready to catch the bottle as it falls.

Energy released from fuels

Equipment

Spirit burners with different fuels in (e.g. Ethanol, Propanol, Butanol)
Top pan balance (0.01g accuracy)
Boiling tube
Clamp and stand
Thermometer
Stopclock
Measuring cylinder
Goggles

Method

Place 50ml of water into the boiling tube and place into the clamp. Measure the water temperature.
Place spirit burner on the balance and record the initial mass.
Next place the spirit burner under the boiling tube, light it and start the stop clock, ensuring that the tip of the flame is just beneath the boiling tube.
After 2 minutes have passed snuff out the spirit burner and record the temperature of the water.
Place spirit burner on the balance and record the final mass.
Repeat this twice more using a fresh boiling tube and fresh water and then calculate the average temperature rise divided by the average change in mass.
Repeat the whole experiment three times for each fuel.

Risk assessment

Care should be taken with the spirit burner to ensure you do not spill any fuel. Goggles should be worn when heating liquids. When replacing the boiling tube take care as it will be hot - it should be left in a test tube rack to cool slowly so as not to crack the glass.

Plant growth and crop density

Equipment

Sunflower seeds
Plot of soil 10m long and 50cm wide
Metre stick

Method

Mark out 5 points in the centre of the width of the planting bed that are 2 m apart.
Around each point mark a 10 square centimetre box.
In the first box plant one sunflower seed, two in the second etc until there are five seeds in the last box.
Water in all the seeds and continue to water every couple days.
Ensure when choosing the planting direction that the plants in one box will not cast a shadow on the plants in another box as they grow.
Allow the plants to grow for one month and then record the height of each plant.
Where there is more than one plant in a box work out the average plant height.

Risk assessment

Ensure hands are washed after working with soil.

Temperature and rate of reaction

Equipment

Water bath
Sodium Thiosulphate solution
Hydrochloric Acid
Measuring cylinders
Boiling tube
Test tube
Led torch
Light sensor & datalogger
Thermometer
Clamps and stands
Goggles

Method

Add 10ml of the Sodium Thiosulphate solution to the boiling tube and place in the water bath set to 25 degrees C.
Add 5ml of the acid to a test tube and also place this in the water bath.
Set up a clamp and stand to hold the boiling tube with the LED torch on one side of it and the light sensor on the other. Set the datalogger to measure light intensity vs time.
When both liquids are at the correct temperature take them out of the water bath, fix the boiling tube into the clamp stand between the torch and the sensor, so that the sensor is against the tube and the light shines through the liquid then tip in the acid.
When the light intensity measured stops changing stop the datalogger.
Repeat the experiment using temperatures of 30, 35, 40, 45 and 50 degrees C.

Risk assessment

Be careful when clamping the boiling tube so that it does not get crushed. Clear up spills straight away. Goggles should be work when pouring liquids.


Monday, 2 June 2014

Polymer strength testing

Equipment

Clamp and stand
Slotted masses (100g) and hanger
Strips of plastic bag of different widths (1 to 5cm in 1cm intervals)
Sticky tape
Ruler

Method

Take a strip of plastic bag and use the tape to secure the end into a loop.
Hang the loop with the taped end over the clamp and secure the loop using some more tape. Use the ruler to measure the unstretched length of the bag.
Add the masses 100g at a time until the loop breaks or until you reach 1kg and record the mass. If you reach 1kg without the loop breaking measure the length to which the loop has now stretched.
Repeat this three times for each width of loop.

Risk assessment

The bag can break suddenly so care should be taken to stand clear when adding masses so that they do not fall onto the floor and land on the feet of the experimenter. The experiment should be set up in the middle of a table so that it does not risk tipping over . The Bag loop should be suspended over the base of the stand to ensure the experiment remains stable.