Investigation to determine the enthalpy change of formation of magnesium carbonate

1. Collect the required apparatus
2. Weigh the weight of the weighing bottle on scales that measure to 0.00 of a gram
3. Then weigh out accurately 0.10g of magnesium metal on scales that measure to 0.0 of a gram
4. Then record the weight of the weighing bottle and magnesium using scales that measure to 0.00 of a gram and add or subtract the magnesium if it is not within 0.01 of the specified amount
5. Using a 50cm3 pipette extract 50cm3 of hydrochloric acid and empty it into the calorimeter
6. Then record the temperature of the acid using a temperature graduated to 0.2 degree divisions
7. Add the magnesium to the acid making sure the thermometer is still in the calorimeter and is easy to see. As soon as the two reactants come into contact start the stopwatch
8. At 30 second intervals record the temperature of the reaction until 4 minutes is reached or 240 seconds
9. Take a repeat reading
10. Then weigh the weighing bottle again on the more accurate scales.
11. Then add 3.5g of magnesium carbonate repeating steps 3 and 4
12.  Again add 50cm3 of hydrochloric acid to the calorimeter by repeating step 5
13. Record the temperature of the hydrochloric acid
14. Add the magnesium carbonate to the acid and take readings every 30 seconds until 4 minutes is reached.
15. Take a repeat reading
16. Produce graphs using the results obtained, work out the calculations and use Hess's Law

Results

Experiment for magnesium and hydrochloric acid

Experiment for magnesium carbonate and hydrochloric acid

Conclusion and Evaluation

By looking at my results they seem to be fairly accurate as they fit the predicted trend for the experiment. For both tests it is obvious that there are some anomalous results. In the experiment for magnesium for test 1 there is one unusual result. It was 34.00°c for 150seconds when it should have been around the region of 33.70°c. In test 2 the temperature was 29.80 for 240 seconds when it should have perhaps been 29.50°c.

For the experiment with magnesium carbonate