Method:
In my experiment there were some things, which I kept the same:
Temperature + surface area of K2CO3;
Volume of acid (0-50 cm3)
Mass of K2CO3 (no more than 1g)
The first thing I’m going to do in my experiment is to make sure that everything in my experiment is safe and there’s no risk for me and other students. I’m going to wear white coat, goggles and generally be very careful when using equipment in the laboratory. After this, I will prepare all equipment I need. Then, I’m going to prepare my stop clock and start the experiment. I have decided, that during the experiment I will be changing the concentration of hydrochloric acid from 0.5 mol/dm3 to 2 mol/dm3 . I weighed out 1g of potassium carbonate into a 50cm3 beaker. I then measured out 50cm3 of 2 mol/dm3 acid into a measuring cylinder. I then added the acid to the potassium carbonate balls and at the same time started the stop clock. I then did the same experiment again to repeat and make sure the results were correct. I then varied the concentration of the hydrochloric acid. For 1 mol/dm3 I used 25 cm3 of acid and 25 cm3 of water, for the 0.5 mol/dm3 solution I used 12.5 cm3 of acid and 37.5 cm3 of water. I’m going to record all the results I get in the first experiment and then, I’m going to put them into my results table. Then, I’m going to do the same experiment the second time, in order to make my variables more accurate. Then, I’m going to calculate the average results and, according to them, plot the graph, which will help me to find if there’re any anomalies in my experiment. After all these procedures, I will be able to evaluate my experiment and analyze all mistakes and errors which could occur in the experiment. After this, I’m going to write about how I can improve my experiment.
Results:
The amount of hydrochloric acid (mol/dm3) |
Time taken (s) First experiment |
Time taken (s( Second Experiment |
Average time Taken (s) |
|
0.5 |
49 |
47 |
48 |
|
1.0 |
37 |
36 |
36.5 |
|
1.5 |
16 |
17 |
16.5 |
|
2.0 |
9 |
6 |
7.5 |
|
The amount of hydrochloric acid (mol/dm3) |
The rate of reaction (g/s) |
|
||
0.5 |
0.02* |
|
||
1.0 |
0.03* |
|
||
1.5 |
0.06* |
|
||
2.0 |
0.13* |
|
||
*-on the graph these results will be multiplied by 10, in order to make it easier to show them on the graph.
Analysis
According to the results I’ve gathered in my experiment I have plotted a graph. From my graph I found that as the concentration of hydrochloric acid increases, the time taken for the reaction to take place decreases. Therefore, the rate of reaction increases as the concentration of hydrochloric acid increases. I have proved this by choosing a variety of four concentrations of hydrochloric acid. The average time taken to end the reaction at 0.5 mol/dm3 was 48s. When the concentration was doubled, (1.0) the time taken was 36.5s, at 1.5 mol/dm3 it took 16.5s, and at 2.0 mol/dm3 the time taken was 7.5 seconds respectively. From these results I can see that the time didn’t halve. When the concentration was doubled from 0.5 to 1.0 mol/dm3, the rate of the reaction has changed from 0.02 to 0.03 g/s. This suggests that there was an anomaly in my experiment. There were several factors, which could cause this anomaly to happen:
Lack of accuracy when measuring the mass of potassium carbonate
Temperature
Inaccuracy caused by human reaction
I’m going to explain each of these factors and suggest the ways to prevent them in my evaluation. Although the time of reaction doesn’t quite halve when the concentration of hydrochloric acid increases from 0.5 to 1.0 mol/dm3, when the concentration of hydrochloric acid increases from 1.0 to 1.5 mol/dm3 the rate of reaction doubles from 0.03 to 0.06. Also from 1.5 to 2.0 mol/dm3, the rate of reaction increases from 0.06 to 0.13, which shows that the rate of reaction is more than just doubled. This shows that my prediction was correct. Also, if we look at the graph we can see that from the point 0.5 to 1.0 the rate of reaction doubles. As the concentration of hydrochloric acid increases from 0.5 to 1.0 mol/dm3, the rate of reaction doubles from 0.5 to 1.0 g/s, which suggests, that the rate of reaction is directly proportional to the concentration of hydrochloric acid.
My graph shows, that the rate of reaction increases proportionally to the concentration of hydrochloric acid, and therefore is directly proportional to the concentration. On my graph I used a line of best fit, in order to show that. The line on the graph is straight, which shows this proportion. However, on my graph I have also showed my actual results and points, which came up as anomalies on this graph. Even so, my graph still shows that I was right in my prediction. I have predicted, that if the concentration of hydrochloric acid was doubled, the rate of reaction would double or time would halve. This graph gives me enough evidence to show, that as the concentration of hydrochloric acid doubles, the rate of reaction doubles as well, which proves that my prediction was correct.