Over the past few weeks we have been learning about most chemical reactions, acids and bases, and endothermic and exothermic reactions are the main things do to with this investigation.
A base is used usually to neutralise acids, we are in the investigation looking to see weather Magnesium, Magnesium Oxide, or Magnesium Carbonate can significantly neutralise Hydrochloric acid.
We aim to in this experiment to see if one of Magnesium, Magnesium Oxide, or Magnesium Carbonate can neutralise Hydrochloric Acid in an exothermic reaction to a PH of seven.
The items needed to do this investigation are:
1. A test tube rack.
2. Three test tubes.
3. Measuring cylinder.
5. A small volume of Hydrochloric acid.
7. Magnesium Carbonate.
8. Magnesium Oxide.
9. Universal Indicator.
10. U.I Chart
The key factors in this experiment are:
* Volume- The volume of the Hydrochloric Acid could change the effect of the base, this is because to neutralise the acid you may need a small amount of acid or there may not be enough base particles to neutralise all the acid particles. This is also an easy factor to change.
* Temperature- The temperature can effect the amount of neutralising goes on, however this is a factor that is not possible to change as it may depend on how much neutralising goes on, or vice-versa.
* Amount of base- This is also an easy factor to change, and its principles lie exactly as the key factor “Volume” does.
* Neutralising time-The time it takes to neutralise the acid is hard to experiment with however, one way of doing it would be to start off with a large volume of acid and add a set amount of base at set times, and checking the PH, when it neutralises then you stop the clock. However I believe that this would not be a very fair test.
* Neutralising accuracy- This factor is to see actually how well the base neutralises the acid, it is the easiest test to do and can easily be made a fair test.
The method will depend on key factors chosen; my group; Myself, David and Nick have chosen with me that we will do Neutralising accuracy, Temperature and Volume.
To start we will put on our safety goggles and get our equipment out, following we will pour 20cm cubed of HCL measured from the measuring cylinder into the test tubes. We will then add the thermometers and add four spatulas of base in the acid and mark down the temperature after the reaction has taken place, whilst also noting down the PH that it has reached when adding Universal indicator.
To do the Volume, instead we will only add one spatula of base, we will not take the temperature and the volume will vary from 2cm cubed to 10cm cubed, we will again note the PH from the result.
Each test will be repeated three times to get fixed results and too see if any mistakes were made.
The diagram will be drawn onto a sheet of A4 paper after the plan.
Fair test and safety list
To make it a fair test we will have to follow these guidelines:
* Measure all substances accurately.
* Only change one variable at a time.
* Wash and dry all test tubes well between tests.
* Do not change the method as you get half way through the experiments.
To keep safe we have to be sensible and follow the usual rules of a science lab, but we have to remember an extra one.
* As this is an exothermic reaction we should be aware that the test tube will get hot as the reaction takes place, so try not to burn your hands if the case is the reaction causes the heat to go to a very high level.
Prediction and comments
We hope to get everything done within the two lesions, if we are unable to do so, we will be prepared to cut the Factor “Volume”.
I predict that the Magnesium Oxide will neutralise the HCL because when an acid reacts with a metal oxide, it produces salt and water, which the latter is meant to be tenths of being PH7 which is neutral, the others (metal and carbon) are meant to produce other substances, like carbon dioxide and hydrogen, as well as salt and water.
I also predict that the temperature will rise in each as we know that it is an exothermic reaction in each, but I think that Magnesium will increase the temperature the most, this is because when a base metal reacts with an acid, one substance it produces is Hydrogen, which is usually of a high heat when reacting with most liquids. Whereas the other bases do not produce Hydrogen.
The other prediction I make is that as we add more acid, the Ph will go further towards PH 1 as there will not be enough base particles to neutralise all of the acid as the acid volume increases.
The Results section
The Results and graphs
The results are produced on Microsoft Excel. There is only a simple bar chart because the data was insufficient to make a line graph from.
Analysis of the results
The results I feel were slightly inconclusive, they really never gave us the answers we wanted and the results really make you think. The prediction I made was wrong, but only on how you look at it.
You see, I predicted that the Magnesium Oxide would neutralise it the best, it transferred the acid to a PH of one, now this could be looked at in two ways, the first is to say that it needs to have a very small amount of acid and a bigger amount of base Oxide, which may make a difference. The other is to say that it is the slowest and poorest to neutralise.
The Magnesium was giving a PH of fourteen every time, so I tend to think that less Magnesium is needed and more acid would be required, before any conclusive results are acquired. Which is the opposite to Magnesium Oxide.
The Magnesium Carbonate was giving off a PH of four to nine, depending on the amount of base or acid added. Now as I see it, this could be the only one to neutralise it to PH seven, this is achieved if you got exactly the right quantities of base and acid to make it do it. I say this because when you look at the two tables of results, then remember how much acid and base there was in each test, then in the middle of the two results is PH seven, so if you start using the middle amount of the two amounts of base and acid, you should get PH seven eventually.
Results conclusion and evaluation
In conclusion, I believe that the methods we chose gave us poor results, if we chose different methods of how much acid or base we planned to use, I think we may have got better results.
I’m slightly disappointed at the results because of the effort the three of us put into the Investigation, however, I think our experiment was not a very fair test. I also believe if further investigating was done, I would think that the best neutralising base would be the Magnesium Carbonate.
The results say that effectively the Magnesium Carbonate is the best to neutralise Hydrochloric acid anyway, as in both tests it came to the closest to being to PH seven, and I think with further tests that would get to PH of seven but there is really no fair test that could get results to show that there is a better neutraliser. It suggests that if you were to judge on Temperature, then the base that changes dramatically with its PH is Magnesium, stating that this could be the quickest Neutralising base as it changes quickly too.