Variables:
Independent: the independent variable is the mass of crucible
Dependent: the dependent variable in this experiment is the mass of residue.
Controlled:
-
The power loss was controlled.
- How long the mixture was heated was controlled.
- The mass of the mixture will be constantly measured.
- A lid would cover the mixture to minimize power loss.
Apparatus:
- Bunsen burner
- Sodium Hydrogen Carbonate
- Lid
- Crucible
- Tongs
- Tripod
- Safety glasses
- Scale
Method:
- The first step would be to collect the apparatus listed above.
- Measure the masses of the following and keep a record of it:
- Sodium Hydrogen Carbonate
- Crucible
- Lid
- After you have measured the masses, add them together, for example mass of lid + the mass of crucible, and make a list like the following:
- Mass of crucible + lid
- Mass of crucible + lid + Sodium Hydrogen Carbonate
- At the end of experiment add, the mass of the residue that was left behind.
- After the results above were collected, you can now start with the experiment. However more accurate results will be obtained if the lid was placed on the crucible at the start of the experiment. This will also minimize the powder loss.
- The lid should be on the crucible every time the experiment is repeated; this will ensure a fair test.
- After the variables above have been controlled, you can light the bunsen burner and start the experiment.
- The time to heat the mixture should always be the same, to ensure a fair test. You should aim to heat the mixture at least five minutes.
- After you have heated the mixture, you should measure the mass of the crucible with the lid still on. You should also keep a record of the masses.
- The mixture should be heated at least three more times, to make sure that the reaction is complete.
- You should also make sure that the lid is always on the crucible, and you should make sure that the heating time is only five minutes. Make sure that you measure the masses of the crucible every time, the five minutes are over.
- When the mass of the crucible stops decreasing then you know that the reaction is complete.
- In order to find out the actual product, you should first calculate atomic mass of the following:
- Sodium Hydrogen Carbonate
- Sodium Oxide
- Sodium Carbonate
- Using the formulae from the hypothesis, try to find the empirical formula, to find out the product of the reaction.
- Then compare the answer, to the final mass, and the closest one to the final mass is the product.
Results table showing data collected during the experiment
After the empirical formula was carried out, the result of Sodium Carbonate closer to Sodium Hydrogen Carbonate, than the result of Sodium Oxide. So we know that Sodium carbonate is the product of the decomposition of Sodium Hydrogen Carbonate.
Conclusion:
After having carried out the experiment, and examined the results, I have found out that my hypothesis was correct. I predicted that only two of the given products, could be possible products. This is because their equations balanced out, and the equation of the third one did not balance out. So it could not be considered a possible product.
Evaluation:
The experiment went smoothly, and accurate results were collected, however some changes could be done if the experiment was carried out again. One of the changes would be more accurate mass measurement. This could have been done by measuring the mass of the variable three times, and then averaging the result. This would have given us more accurate masses, since the masses are key factors in obtaining the product. Another change would be the time taken to measure the crucible. We could set a three minute break after each five minute heating. By doing that the heat that was lost by the mixture could be kept constant the whole time. We also started heating the mixture without a lid on top of our crucible, which caused in the loss of powder.