How I will make it a fair test?
- Their must be the same amount of either Zinc or Copper Sulphate (depending on which I choose to be the constant and which I choose to be the variable depending on my preliminary results)
- The temperature before the reactions must stay the same
- The time must stay constant
- The same equipment must be used
- The equipment must be clean before each reaction
How much to use?
When zinc varies: 2 to 8g in 30ml of CuSO4
When copper sulphate varies: 30 to 120ml mixed with 6g of Zinc
Preliminary results:
The first preliminary results table has a variable which is the quantity of Zinc powder in a mixture of cooper sulphate which has the same amount of 30 ml. The result stagnates because of the fact that there aren’t enough copper sulphate molecules, which can’t react with the overdose of zinc powder. This is shown by the graph above. The zinc ratio is getting higher than the CuSO4.
In the next result chart the quantity of zinc powder will be 6g and the variable will be the amount of copper sulphate to see if the results will rise or lower.
The second chart of results shows that the more copper sulphate solution is added with only 6g of Zinc powder, the temperature falls very slowly, bit by bit. This time, the copper sulphate ratio is getting bigger than the Zinc.
Prediction:
I believe that as the amount of zinc powder increases, the temperature after the reaction will be greater, therefore the temperature change will be greater. I think this because I know that the reaction Zinc + Copper Sulphate is exothermic, meaning that it gives out heat during the reaction. As it gives out heat, it will be hot, so the solution must be warmer than it was before.
Results table:
The third results chart will have the same amount of copper sulphate and zinc powder as a variable (1 to 6 g).
The result curves due to there aren’t enough copper sulphate molecules by this time because they have all reacted already. This is shown by the graph below
What happens?
This type of reaction is called exothermic because when the two elements are mixed together it gives out heat, which is made by breaking the bonds and cools down by rebonding together. This process happens in a matter of fractions of a second. The action happening with the atoms in this experiment when it has a reaction, it’s called displacement.
The equation for this reaction is:
Zn(s) + CuSO4 (aq) Cu(s) + ZnSO4 (aq)
Blue Liquid Displacement Red, brown
Evaluation
This experiment has shown me that the reaction between Zinc and Copper Sulphate is exothermic, giving out heat. I have learnt that as you increase the amount of zinc the temperature rises. This is because there is a larger surface area of Zinc to react with the same amount of Copper Sulphate. I have also learned from the preliminaries that as you keep the zinc amount level and vary the amount of Copper Sulphate, the more Copper Sulphate there is, the less the temperature after. I think this is because there is to much Copper Sulphate trying to mix with a small amount of Zinc, and as such, not much energy is needed to make the 2 chemicals react, so less heat is given out.
If I were to do the experiment again, I may well decide to explore what happens when you keep the zinc amount level and vary the amount of Copper Sulphate. This is because I would like to know whether the reactions kept getting colder, or weather they curve off as you get more Copper Sulphate. I would do this experiment because then I would be able to understand what happens in the reaction, Zn(s) + CuSO4 (aq) Cu(s) + ZnSO4 (aq). I would like to know whether my preliminaries were wrong, and that the temperature wasn’t supposed to decrease.