How the temperature of hydrochloric acid affects the rate of marble chips dissolving in the acid.

I will wait until 20cm3 of volume has been collected in the burette and I will stop the clock and record my results in a table.

I will repeat the experiments twice then take an average.

I am using this method because I think that it will give me good results and if I did the experiment again then I could use it again and be sure that it would work.

Recording Results

As I am doing the experiment I will record the results in a suitable table like this:

Temperature of Hydrochloric Acid

Time to collect

20cm3 of gas (s)

Test 1

Test 2

Average

25 o C

30 o C

35 o C

40 o C

45 o C

50 o C

55 o C

60 o C

I will repeat each temperature interval to ensure reliable results and take an average.

Safety

* I will wear goggles so I don't get anything splashed in my eyes or face

* I will be careful when handling the acid not to tip it up or overheat it

* When taking the temperature of the acid I will ensure that I don't use the thermometer when heating the acid over the Bunsen burner

Variables

Possible variables are:

* The temperature of the acid

* The amount of acid or marble chips

* The concentration of the acid

* The surface area of the marble chips

The variables I am using and keeping the same are:

* I will change the temperature of the acid in regular intervals of 5 o C. By doing this the collision theory can be introduced. The hotter the acid particles get, the more they move around and 'bump' into the marble chips causing them to be dissolved and more gas to be given off.

* I will use the same amount of marble chips and acid each time, if I used different amounts each time then it would be like doing different experiments.

* I will use large surface area marble chips; if I used assorted surface areas this would not be a fair test.

* I will use the same concentration of acid each time because a stronger or weaker concentration will alter the time it takes for the marble chips to give off gas and then the experiment will not be a fair test.

Preliminary tests

In the previous experiments I performed, I found out which variables to use and I worked out from the results which intervals of temperature to use. I also checked the results and drew up a better results table than the one I had planned to use in the experiment originally.

Obtaining Evidence

My results were:

Temperature of Hydrochloric Acid

Time to collect

20 cm3 of gas (s)

Test 1

Test 2

Average

25 o C

29.13

27.72

28.43

30 o C

24.19

25.39

24.79

35 o C

21.41

9.82

20.62

40 o C

5.40

7.21

6.31

45 o C

4.22

3.97

4.10

50 o C

2.52

2.24

2.38

55 o C

1.19

0.82

1.01

60 o C

8.97

9.17

9.07

Analysis

As the temperature increases the rate of reaction increases also. My graph shows a slightly curved line upwards to show that the rate of reaction increases as the temperature increases, it is curved because the results are not exactly accurate but the curve is only minute. I can prove this by the information I used in my prediction. The more the particles are heated up the more collisions are made and so more gas is given off in a shorter amount of time. The line of best fit on my graph is how I expected it to be and my prediction shows this.

On my graph there are not any anomalous results. There are a few that are not on the line of best fit, but they aren't as far away to count as anomalous results. The lack of anomalous results shows that the experiment was carried out accurately and didn't have any mistakes or error in the procedure that I planned. The results that I have collected did turn out the way I expected and I think that they are very accurate.

Evaluation

I think that the experiment went very well. This is because I got all the results that I wanted and they look very good when plotted on the graph. The results were very accurate and so I am able to make a firm conclusion. From looking at my results I can see that there were no poor results, which was a good thing, and it proves that everything went very well.

The method that I wrote was reliable and worked well. I followed it and the results that were gathered from the experiment are very accurate and gave me good figures to use and make into a suitable graph. I would use that method again because it was quite simple and easy to follow. If I had to do this experiment again I might have used concentration of the acid as my variable to see if it gives as good results as temperature of the acid, if I did that I would have to take other variables into account and other precautions would have to be taken to make it a fair test e.g. what kind of water I would use for concentrating the acid.

The results may be higher or lower because of the strength of the acid. In my preliminary test the results are higher or took more time because the concentration of the acid wasn't as strong as the acid I used in the proper experiment.

The graph I have drawn from these results is very reliable. It has no anomalous results and every point is on the line or very close by. This shows that I did a very good and accurate practical experiment. The evidence I have gathered is good enough to gather a conclusion. The results and graph show a minutely curved line, which shows that as temperature increases so does the rate of reaction.

If I had to improve my method I would do more repeats to make certain that my results were accurate. I may also do two different types of concentration to see how that affects the rate as well as temperature.