Osmosis
... the paper towel around the boiling tube with an elastic band at the top and twist the paper towel at the bottom to make sure all of the boiling tube is cover with paper towel. 5. Place the boiling tubes into the boiling tube rack. 6. Using a measuring cylinder measure 40cm³ of water from the water bath that is set at 39°C. 7. Take one boiling tube from the rack and make sure that you fully damp it with water. 8. Take the second boiling tube and using a spray bottle, spray it 7 times. 9. Take the third boiling tube and spray it 3 times using a spray bottle. 10. Leave the fourth boiling tube completely dry. 11. Then add the water (40cm³) into the boiling tube. 12. Then add the next 40cm³ of water to the second boiling tube after a minute’s interval from the first boiling tube. 13. Do this for the other two boiling tubes keeping each of them after a minute’s interval. 14. When the water has been added to the boiling tubes, cover them with bungs and a thermometer which has already been placed within the bung. 15. Record the temperature, after each minute. Carry this on for 10 minutes. 16. Repeat the experiment using the water from the other water bath which is set at 52°C. 17. Put all the results in a table. Factors To make my experiment a fair test I will: Make sure that the same size of paper towel is used every time, so that it does not effect the results as one paper towel size would be bigger than other which can probably make our results unreliable as the paper towel would absorb more heat energy and less of it will be released. The starting temperature of the water is the same in all the boiling tubes, so that al results are equal and fair. If we start all of them at different temperatures they will have very different results and we shall not be able to achieve our aim. The experiment is started at the same time or at equal intervals so that the results do not change and everything is timed equally and the results would be reliable. Also if not carried out at equal intervals more heat can be released by one of the boiling tubes than the e other so it is necessary that all of them are started at equal intervals and timed equally. Keep all the boiling tubes in the same surrounding conditions and atmosphere, if one of them is in a sunny aspect and the others are in a shady aspect, it will change our results and the experiment will be unfair as the heat of the sun would be warming the boiling tube up. If an area is more humid, it will affect the rate of water and if one of the tubes are placed in a more humid place than the other it will change our results and they will not be accurate. The volume of the water should be the same in all the boiling tubes so that the heat energy in each boiling tube passes through the same amount of water as in the other boiling tubes. If the volume was not the same it could effect out results. The same thickness of paper towel used as it would take longer for heat energy to be absorbed by a more thick paper than a thinner one. The same colour of the paper towel used, as different colours absorb different amounts of heat, dark colours such as black absorb more heat than lighter colours. The thermometer should be placed at the same position in every boiling tube, as some areas in the water would be cooler then others. If the thermometer in one tube would be put at the very bottom and in the other one at the very top, it will be an unfair test and the results would be unreliable. The one varying factor in my experiment will be the amount of water sprayed on the paper towel wrapped around each tube- test tube one will have a dry paper towel wrapped around it – test tube two will have a paper towel wrapped around it that has been sprayed three times, test tube three will have a paper towel around it that will have been sprayed seven times and test tube four will have a paper towel wrapped around it that has been soaked fully with water, this will allow me to compare the cooling effects of different amounts of water. Safety Precautions • If there is a spillage I shall clean it up so no accidents will be caused. • Handle boiling tubes and beakers with care as they are made up of glass. • Place all bags and stools under the tables so no accidents are caused. • As hot water and kettles are involved, I will be careful with it so I do not burn my self. Recordings I will measure the temperature in this experiment. The t...