Results Table 2.1

Perform 2 more trials, repeating steps 15 two more times.
Data collection and processing
Raw Data Table:
Trial 1
Trial 2
Trial 3
*Zinc powder was added to the cup.
Observations:
Before we added the zinc, the CuSO4 solution was a bright aqua blue color. The zinc was a fine powder, colored grey. When we placed the thermometer, there was no change on the part of the liquid because no reaction was being acted upon it. At the 180second interval, we added the zinc. It first floated on the surface of the solution but as we continued to stir, it mixed with the solution, taking on a shade closer to brown. The solution reflected that same brown color as we started but then changed color too, taking on a darker tinge of blue. By the end of the experiment, we could observe excess zinc resting on the bottom of the cup. The solution had actually turned shades lighter.
Data Processing:
I will first calculate the averages of all three sets of trials to represent the temperature change of the solution. I will then plot the temperature (yaxis) against time (xaxis), as well as extrapolate the curve to 3.0 minutes to establish the maximum temperature rise. Next, I will calculate the enthalpy change for the quantities used, making appropriate assumptions. Finally, I will calculate the enthalpy change for one mole of Zn and CuSO4(aq), and write the thermochemical equation for the reaction.
Sample calculations:
22.5 + 22.5 + 22.5 = 67.5
67.5 / 3 = 22.5°C
Results Table 2.2
shows the averages
of all three sets of trials
*Zinc powder was added to the cup.
Figure 1.1 shows the average temperatures of the solution at various times.
The enthalpy change for the quantities used:
Sample calculations:
M = 25*1.64
= 26.64
C = specific heat capacity of water = 4.18
∆T = (Tf – Ti)
= (21.6  22.5)
= 0.9
∆H = MC∆T
= 26.64(4.18)(21.6  22.5)
= 26.64(4.18)(0.9)
= 100.22 kJ mol1
Average enthalpy change:
Sample calculation:
100.22 + 103.46 + 95.931 = 299.611
299.611 / 3 = 99.87 kJ mol1
Conclusion:
As a result, we got that the enthalpy change of reaction was 99.87 kJ mol1. The accepted value for the enthalpy change for the displacement reaction of the following as seen in CHEMICAL ENERGETICS (ILPAC 2) EXPERIMENT 2.1 is 217 kJ mol1 :
Zn(s) + Cu2+(aq) → Cu(s) + Zn2+(aq)
Clearly, our results determined a significantly larger enthalpy change. By calculating the percentage error, we can determine just how large.
Sample calculations:
error = [(99.87 – (217)) / (217)] x 100%
= 53.98
My calculations revealed that there was a percentage error of over 53%.