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Introduction

Investigating the Effect of Concentrations of Solutions Introduction In this experiment we will be investigating the effect that the concentration of salt in water has on the resistance of the solution. The possible variables I could use are as follows: Mass of salt, temperature, voltage used, volume of water used to dissolve salt. The input variable will be the amount of salt we mix in the solution, and the output variables resulting from this will be the current and the resistance. I have chosen to vary the amount of salt because I think that varying the mass of salt is easier and more accurate than varying the other variables. I am going to keep the test fair by only varying the amount of salt I put into the solution, by carefully weighing its mass electronically, and by carefully measuring the amount of water I use to dissolve the salt in each time with measuring cylinders, and also stirring the solution until all of the salt has disappeared to make sure that it is accurate showing how salt effects conductivity. I will also carry the test out at room temperature. The variables I am keeping constant are: * The input voltage used * The volume of water used * The temperature ...read more.

Middle

certain constants to be used for example I decided that 75ml of water was the best amount to use as any less wasn't enough to cover the anodes and keep its contact equal with the water. I also decided to keep the input voltage at 4 volts as this produced enough to give good results and didn't produce too much poisonous chlorine if kept on a little longer while taking results. Results next page:- Results Below is a table of the results I obtained and the results of my repeat. The temperature of the water was always constant at 21�C. The electrodes are kept 2cm apart in each test. Test 1 Test 2 Ave. Volume Of water (cm�) Mass Of salt (g) Voltage (V) Current (A) Resistance (?) Voltage (V) Current (A) Resistance (?) Ave. Resistance (?) 75 0.5 3.37 0.11 30.6 3.38 0.11 30.7 30.65 75 1.0 3.36 0.14 24.0 3.38 0.14 24.1 24.10 75 1.5 3.37 0.16 21.1 3.37 0.15 22.5 21.80 75 2.0 3.37 0.17 19.8 3.36 0.17 19.8 19.80 75 2.5 3.36 0.19 18.7 3.36 0.18 18.7 18.20 75 3.0 3.37 0.20 16.9 3.37 0.20 16.9 16.90 75 3.5 3.36 0.22 16.0 3.36 0.21 16.0 15.65 75 4.0 3.36 0.24 14.7 3.37 0.23 14.7 14.35 Analysis To ...read more.

Conclusion

This pattern suggests that my results are reliable. However, it would be preferable if the experiment could be carried further so that I could make sure of this pattern, but I didn't have enough time to do this. The problems of this experimental procedure are detailed above describing possible causes of the anomalous result, and problems could be improved by: * Reducing human error with more care and attention * Checking equipment for faulty connections, or using newer equipment * Using distilled or purer water for the experiment instead of tap water * More accurate scales running to more decimal points * More thorough cleaning of equipment after obtaining each result The experiment could be continued by using higher amounts of salt in the solution, until no more can be added (the solution is saturated), or even by using different solutions, like other salts, or effects of using acid instead of water etc. It would also be interesting to investigate the effects of using other salts, and whether they affect resistance similarly. All of these could provide more insight into the relevance of this experiment, and give a wider view of what material will allow the conduction of electricity. Jason Millman 11A ????? ...read more.

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