Investigate the effect of changing the concentration on the rate of a reaction.

In the dilute acid, the rate

of reaction will be low

because of the fewer acid

particles. Thus being fewer

successful collisions.

In the concentrated acid,

the rate of reaction will be

high because of there being

more acid particles.

Thus being more successful

collisions.

Measurements: I will be measuring the magnesium ribbon. I will measure the volume of the HCL acid. I will also measure the amount of hydrogen produced every 10 seconds using a gas syringe. The time will be measured in seconds using a stop clock.

Pre - Test:

Time (sec)

Test 1

Test 2

Test 3

Average (cm³)

20

20

21

21

20.6

40

35

36

34

35

60

46

46

46

46

80

56

54

57

55.6

00

60

60

60

60

20

61

60

61

61

Time (sec)

Test 1

Test 2

Test 3

Average

20

29

31

30

30

40

51

52

53

52

60

60

60

60

60

80

60

60

60

60

00

60

60

60

60

20

60

60

60

60

This pre -test was carried out so we can get a general idea of how the magnesium ribbon will react when added to the hydrochloric acid. By doing this we know what to expect in the experiment.

Firstly, we collected our

equipment and placed it in

the centre of the bench. This was done so that the equipment wouldn't drop on the floor.

We then had to cut out the magnesium ribbon into smaller pieces measuring exactly 2cm. A ruler was used here to give us an accurate measurement.

We had to place the 2cm ribbon into a test tube and using a measuring cylinder we had to measure 0.25ml of the hydrochloric acid. This was for the first test.

After Measuring the acid we then had to pour it into the test tube with the ribbon inside and then time how long it took for it to disappear using a stop clock.

The results are shown below:

Concentration of Acid

Time for reaction to reach completion (sec)

Average (sec)

Test 1

Test 2

Test 3

0.25

42

40

36

39.25

0.5

22

19

53

64

0.75

90

93

92

92.25

82

80

75

78.75

2

33

27

30

31.25

The graph that I have constructed by hand (overleaf) shows the results of my experiment on the rates of reaction.

My results show that in increasing the concentration of the acid will increase the rate of the reaction.

When you look at the graph you'll see that it all the points curve from the bottom upwards. This means that the more concentrated the acid the faster the rate of the reaction increases.

When I look at my results I come to the conclusion that, as my prediction states, that in increasing the concentration of the hydrochloric acid will increase the rate of the reaction. This is the reason my graph is sloping down.

The scientific theory states that in a dilute acid, the rate of reaction will be low because of the fewer acid particles. Thus being fewer successful collisions.

But in a more concentrated acid solution the rate of reaction will be high because of there being more acid particles. Thus being more successful collisions.

This experiment was easy to do because I knew what I had to do and I had done a similar experiment before. The aims and objectives were very clear. I just had to look at my table (shown in the planning section) to find out the concentration of the hydrochloric acid, put the magnesium ribbon into the test tube and add the acid. From then on it was pretty easy to do and enjoyable.

I think that performing the pre - test helped me become familiar with setting up the equipment and taking measurements. We knew exactly what we had to look for so it wasn't very hard. We had gone through planning the experiment so many times I could practically do it without looking at my plan.

The results of my test were very accurate as I repeated each concentration three times which enabled the elimination of random values, which wouldn't help me in constructing my graph or the rest of my coursework.

Whilst I was doing my experiment I straightaway knew how I could make improvements and more came when the test was over. I could've used a larger range of concentration to get more results and construct a more detailed graph to see any other abnormal values. I could've also used different types of acids to compare graphs and results. I could also of used a larger range of magnesium ribbon. In other words just increased the length of the ribbon.

The method I used for this investigation was quick, simple and appropriate for getting the results. Working with 3 other people speeded up the process but I felt that if we did our experiment separately and compared results the outcome would've been more precise.

Max Buadi 10D