Neutralisation Reaction Essay, Research Paper

The Problem: We are trying to find out whether the concentration of acid affects the heat produced in neutralisation.

Background Knowledge: The knowledge I know that will be relevant to the experiment is-:

*Neutralisation always produces a salt

*An alkali can neutralise acid

*Alkali’s are not the only compounds that can neutralise acids

*When acids and alkalis mix, they try to cancel each other out

*Water is produced from the reaction

*To see if neutralisation has taken place, we have to use an indicator

*On a pH scale, neutral is number 7

Below is a pH scale, giving some examples that we use in everyday life-:

Plan: We will be completing a series of experiments that will have three main liquids in each one. These liquids are water, Sodium Hydroxide and

Hydrochloric Acid. We will measure the difference in temperature after we have added the alkali which will be Sodium Hydroxide. Altogether, we will carry out a total of 7 experiments and these are shown in the results table. We will try different concentrations of Hydrochloric acid, Sodium

Hydroxide and water. The equipment that we will use will be a thermometer, two beakers, a pipette, universal indicator, and the three liquids mentioned earlier. The universal indicator will tell us whether the experiment is correct by indicating whether the reaction is neutralisation .

We will complete seven tests and take the difference in temperature from the start of the experiment and at the end. The largest amount of any liquid that we will use is 20ml. The lowest amount is 5ml. We will measure the difference in temperature with the thermometer. We will record the start temperature and then the end temperature.

Fair Testing: To make sure that the test is fair we will measure the amounts of each liquid very carefully. Each time we start a new test, we will have washed and dried the beaker out as not to leave any of the liquids from the last experiment in. Instead of measuring the amount from a certain temperature, we will take the start temperature and then one at the end. The difference will then be taken. We will use a different pipette for each liquid, and the water will be taken from the tap. The Hydrochloric acid and the Sodium Hydroxide will be taken from a bottle. We will time the experiments for approximately 3 minutes each. This should give time for the different liquids to mix together and hopefully neutralise. There are many things in the experiment that could be considered not fair but that is why we are doing the experiment, to see how the different amounts of each liquid react. In each of the experiments the total amount of liquid in the mixtures will be 40ml. One of the experiments does not contain water, but otherwise, the lowest amount in any one is 5ml and the highest 20ml.

Having 40ml of liquid in each mixture will keep the experiment fair.

Prediction: My prediction is that the more the amount of Hydrochloric acid in the mixture, the higher the difference in temperature will be. I think this because the particles in the Hydrochloric acid are much more reactive than the particles in the Sodium Hydroxide. This will mean that more of a reaction will take place and more heat will be produced from the reaction.

I do not think that the difference in temperature will be that great because there is not enough of each liquid in the mixture to make a hugely noticeable difference. I think that the mixtures with the more acid and

Sodium Hydroxide will produce the greatest change in temperature because the are more reactive together than say large amounts of water and smaller amounts of sodium and acid. The test that I think will produce the greatest change will 20ml of acid and 20ml of Sodium Hydroxide.

The mixtures with the least amount of reaction will be the ones with large amounts of water and smaller amounts of acid. This is because the acid is more reactive than the water and is only present in small amounts while the water is present in large amounts. The tests with equal amounts of each substance will result in the test being the same as others with equal amounts of each substance.

Method: We set up the equipment and then started testing. We were careful with each part of the experiment so that we would get the balance right. We set the stopwatch off. Our results were recorded in a table.

Below is a diagram of our equipment-:

Results:

The amounts that we used are shown below-:

Our results are shown below-:

Conclusion: My results were mainly as I predicted with the largest increases in temperature when the mixture contained more of the Sodium

Hydroxide and Hydrochloric Acid. This means that my theory could well be right. This would mean that Sodium Hydroxide and the Hydrochloric

Acid react much more than when diluted with water. The higher the concentration, the more particles of both substances are available to react with one another because they are more concentrated. I predicted that the acid would be more reactive with the Sodium Hydroxide than the other way round and would therefore produce a greater increase in temperature.

I made my prediction on the basis that the Chlorine in the acid is more reactive than the components in the Sodium Hydroxide.

Evaluation: The design of the experiment and the results did not produce clear conclusions from the aim of the experiment which was to which was to investigate the speed of a neutralisation. This was demonstrated in unclear patterns in the results. This was because the dilution’s were not confined to both Sodium Hydroxide and Hydrochloric

Acid equally. Instead, we mistakenly diluted one or the other which made the experiment an unfair test.

If we were to do the experiment again, then we could try different types of reactions and make the experiment longer. This experiment was not the best experiment to do this kind of test and further research might produce a better test.

There was a slight pattern that fitted slightly with my prediction and that was test 1 and 6 which had a lot of acid and Sodium Hydroxide. This fitted with my prediction and produced the highest temperature increase.