GCSE Chemistry
An Investigation Into How the Mass of Zinc Effects the Heat Change In the Displacement Reaction Between Zinc and Copper Sulphate
This investigation aims to look at how a factor can change the amount of heat produced in a displacement reaction. The displacement reaction that will occur during this experiment will be an exothermic reaction, which will mean that heat will be given out to the surroundings.
The possible independent variables that could be investigated are:
- The mass of zinc
- The pressure of the surrounding atmosphere
- The concentration of the copper sulphate
- The surface area of the solid reactant, i.e. the zinc
- The volume of copper sulphate
- The light intensity
- The pH of the copper sulphate
I have chosen to vary the mass of the zinc, as it is simple and easy to measure and control. Therefore the controlled variables will be:
- The concentration of the copper sulphate
- The volume of the copper sulphate
The dependent variable that I will be measuring, will be the temperature change of the reaction. To do this I will have to measure the initial and final temperature of the reaction.
Hypothesis
I expect that the investigation will show that an increase in the mass of zinc will cause an increase in the heat change, and therefore the temperature change. This is because a doubling in the amount of zinc would mean that there would be twice as many particles within the mass, therefore there will be twice as many collisions with the copper sulphate particles. The double in the number of successful collisions would mean that there are twice as many bonds in the reactants being broken. This would result in the heat change being doubled.
For example, if the temperature change for a mass of 0.2g of zinc and 25cm³ of copper sulphate, was 10°C, then I would expect to see that the temperature change to be 20°C, for a mass of 0.4g of zinc and 25cm³ of copper sulphate.
Due to my hypothesis, my predicted graph looks like this:
Heat
Change (°C)
Mass of zinc (g)
Preliminary work
The preliminary work that was carried out determined whether a significant change in the temperature could be observed using the various masses. As the results that were produced in the preliminary experiment were accurate, it was decided that they would be used in the actual experiment.
