Note: I couldn’t paste in pictures and diagrams so please excuse any large spaces.
Planing my investigation
1.Firstly I will measure 20ml of Copper Sulphate solution (CuSO4) in a measuring cylinder, for precise accuracy, and then pour the solution into test tube. I will place the test tube into a beaker and insulate the test tube, for minimum heat loss. (As shown in the diagram above.)
2.Secondly I will measure the required amount of Zinc (Zn) on a weighing scale, again for precise accuracy.
I will then measure the starting temperature using a thermometer. Next I will pour the Zinc into the test tube containing CuSO4.
3.Finally I will measure the final temperature using a thermometer and record the temperature rise in °c. (I will carry out all my experiments under lab safety precautions.)
*I will vary the mass of Zinc, & use the following Zinc weights: 0.5g, 1g, 1.5g, 2g and 2.5g.
*I will repeat each experiment twice for an average.
For a fair test I will need to control many variables. I will stir the reaction an accurate number of times. I will record the temperature with a thermometer waiting until the temperature begins to drop so the temperature has fully risen. I will measure the volume of the CuSO4 solution accurately with a measuring cylinder, and make sure the concentration of CuSO4 is constant throughout all the investigation. I will weigh the Zinc with a weighing scale and make sure it’s free of any impurities.
Prediction and Science behind Plan
I predict increasing the mass of Zinc will increase the temperature rise of the Copper Sulphate solution.
When Zinc reacts with copper sulphate, the Zinc atoms displace the Copper atoms from Sulphate to form Zinc sulphate and Copper. This is simply because Zinc is more reactive than copper. This is called a displacement reaction.
Zinc + Copper Sulphate Copper + Zinc Sulphate + Energy
Zn + CuSO4 Cu + ZnSO4 + AH
For this chemical reaction to occur, the Zinc and Copper Sulphate particles must collide. For an effective collision there must be enough energy involved in the collision to break the chemical bond between Copper Sulphate, this requires energy absorbed from the surroundings, so this process is endothermic (The reaction in which energy is released). However heat will be transferred to the surroundings when Zinc and Sulphate form a bond so this is an exothermic process. The overall reaction will be exothermic because more energy is released when bonds are formed than is needed initially to break the bonds. This chemical reaction happens between every effective collision of Zinc and Copper Sulphate atoms.
Therefore increasing the weight of Zinc poured into the copper sulphate solution increases the number of Zinc atoms. So there will be more collisions and they will occur more frequently, increasing the probability of an effective collision. Consequently more chemical bonds will brake; more heat will be produced, and the temperature will rise to a higher extent.
Mass of ZincTemperature rise in °c
1.0 gram96.57.75 (anomaly)
I obtained all my evidence under lab safety precautions. I used a range of weights valid for my investigation, ranging from 0.5 to 2.5 grams, repeating each experiment twice for an average so I could get reliable evidence. I weighed Zinc using a weighing scale, measured the temperature with a thermometer, and measured Copper Sulphate with a measuring cylinder. All for precise, accurate, valid and reliable evidence.
A Graph to show the effect of increasing the mass of Zinc on the temperature change of a Copper Sulphate solution
Average temperature rise Anomalous result
Line of best fit
There is a positive correlation on this graph, as Zinc gets heavier the temperature of the solution gets hotter.
Using my graph and table I noticed some trends in my result. One is; as the mass of Zinc increases the temperature of the solution rises. A numerical trend exclusive of my anomalous result is the average temperature rise between every variable is about 6 degrees centigrade.
All in all I can simply say, when Zinc reacted with Copper Sulphate it produced Zinc Sulphate, copper and a small amount of heat. Meaning increasing the amount of Zinc poured into the Copper Sulphate solution, increases the temperature rise of the solution.
In this chemical reaction the reactants are Zinc and Copper Sulphate. The products are Zinc Sulphate, Copper and heat energy.
Zinc + Copper Sulphate Copper + Zinc Sulphate + Energy
Zn + CuSO4 Cu + ZnSO4 + Ah
The reason why Zinc displaced Copper from Sulphate is because Zinc is higher than Copper in the reactivity series meaning Zinc is more reactive. This is known as a displacement reaction.
When this chemical reaction occurred, Zinc and Copper Sulphate particles collided. For an effective collision there must be enough energy involved in the collision to break the chemical bond between Copper Sulphate, this required energy absorbed from the surroundings, so this process was endothermic (The reaction in which energy is released). However heat was transferred to the surroundings when Zinc and Sulphate formed a bond so this is an exothermic process. The overall reaction was exothermic because more energy was released when bonds are formed than is needed initially to break the bonds. This chemical reaction happened between every effective collision of Zinc and Copper Sulphate particles.
Therefore increasing the amount of Zn increased the probability of an effective collision, so there was more collisions, and they occurred more frequently. Hence more bonds broke, more heat was produced and the temperature rose to a higher extent.
As a whole my results and experiment was successful. I got the required amount of intelligence to support a conclusion.
My quality of results was beneficial, as I used many precision, accurate apparatus. Electronic weighing scale for weighing the mass of Zn, measuring cylinder for measuring the volume of CuSO4, and a thermometer for measuring the temperature. However there could be an uncertainty in the measurement. When I poured Zn or CuSO4 into the narrow test tube, some of it could fall onto the side without me knowing, causing a dramatic change in results.
That’s probably how I recorded the anomalous result. It was the second experiment, when I was using the mass of a gram, and the temperature on average only rose 7.75°c. Another reason why this took place was probably because I did not stir the solution equivalently and did not let the temperature rise to it’s fullest extent.
I think my plan was suitable and generally reliable for a conclusion. However I could think of improvements, for a better plan:
*I could use a funnel to pour Zn and CuSO4 into the beaker to minimise loss of reactants
*I could time the reaction so all experiments have an equal time to react
*I could repeat the experiment further for a better average
For further work to provide additional evidence, I could redo the experiment but investigate the effect of Zn on different volumes of CuSO4, and see what differences take place then.