Variables
Throughout the entire experiment, I will need to ensure that certain variables are kept the same. These are the controlled variables, which are necessary to be sure that the experiment is fair and as accurate as possible throughout the experiment. If there were no controlled variables our results could show major anomalies, and this result would prove that something was not going as planned.
Input – Concentration of hydrochloric acid.
Output – Amount of carbon dioxide given off.
Control – Marble chips, amount of acid, time of experiment.
Prediction
I predict that the more highly concentrated the acid is, the more gas there will be given off from the marble chips. This prediction is based on ‘The collision theory’ as the higher the concentration, the more molecules there are meaning that more collisions occur between the object and the atoms in the acid solution.
Diagram
Method:
The apparatus is set up as shown in the diagram. I accurately measure out 2.00g of marble chips and place them into a conical flask; the chips will need to be of a similar size to make this a fair test. Then I will need to add 50ml of hydrochloric acid to each of the experiments performed to make this fair, using a measuring cylinder to be accurate. We have chosen to use acid, as it will be similar to the acid contained in our stomachs. The solute and solvent are mixed together to form a solution. I will then need to observe the gas syringe every 10 seconds to record the amount of gas given off from the marbles. The results will be noted in a table after the chosen time of 5 minutes for the experiment.
Conclusion
By observing these results I conclude that the higher the concentration of acid there is, the less time it takes for the marble chips to be neutralised. This can be seen by looking at the results as they represent the time and amount of gas given off. This proves that my prediction was right.
This is related to ‘The Collision Theory’ as there is a trend with the acid concentrations as the higher the concentration, the more collisions occur due between the amount of molecules and the solute.
Evaluation:
I believe that my results were almost as accurate as I could get them, and managed to see that the prediction and the conclusion matched. However, there are several things that I would want to change. If I had the chance to perform the experiment in the same lesson the results would have been further accurate. There are no anomalies, but it would further help if those experiments were carried out so that the results could be more similar than those I have as some are not very consistent. Apart from that, my experiment went very well
To improve the entire experiment, I would make sure that all the tests were carried out during one lesson, as it would ensure that the chemicals and limestones were identical. It may have been that the results being slightly inconsistent came from using a slightly different acid or limestone.
