# Enthalpy Change

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• Published : June 10, 2012

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Determine the enthalpy change for the reaction (ΔHfθ) between zinc and copper sulphate solution, giving full practical details.

Aim
To determine the enthalpy change for the reaction between zinc and copper sulphate. Zn (s) + CuSO4 (aq) ZnSO4 (aq) + Cu (s)

Introduction
In the study of energy (thermodynamics) the system refers to the reacting chemicals (zinc and copper sulphate solution) and the surroundings is everything else (atmosphere, container, temperature probe). By adding an excess of zinc powder to a measured amount of aqueous copper sulphate and measuring the temperature change over a period of time, you can calculate the enthalpy change for the reaction.

Method
* Using a pipette and pipette filler carefully measure out 25.0 cm3 of copper (II) sulphate solution, concentration = 1.0 mol dm3- and pour it into a polystyrene cup. * Stir with a thermometer, start a stop clock and measure the temperature every 30 seconds. * Meanwhile weigh out approximately 6g of zinc powder.

* at two minutes (when the temperature of the solution is constant) add all of the zinc powder to the cup and stir carefully with the thermometer. * Continue to stir and record the temperature every 30 seconds up to the five minute mark. Then record the temperature every minute until 13 minutes are reached. * Write up results on graph paper

Diagram
Stick photo in here
Table of results

Time min| Temp °C|
0.30| 23|
1.00| 23|
1.30| 23|
2.00 (Zinc dropped in)| -|
2.30| 53.2|
3.00| 62.1|
3.30| 69.0|
4.00| 70.1|
4.30| 70.4|
5.00| 69.1|
6.00| 68.0|
7.00| 66.8|
8.00| 64.6|
9.00| 62.2|
10.00| 61.6|
11.00| 60.0|
12.00| 57.8|
13.00| 57.2|