The amount of acid I have decided on is 10ml. And so the amount of marble must be in excess - 3g.
I can measure the speed of the reaction by how much gas is given off. I can measure this in cm3 in a gas syringe. When the experiment takes place, I will take the reading every 10 second to get a good graph for the results. If the reaction goes very quickly, I will take the readings every five seconds.
To be sure I can rely on my results I will repeat he experiment twice or three times if necessary, because there is chance of inaccurate results for many reasons.
I learnt from the trial experiments that it is quite hard to start a stopwatch, pour acid and stick a bung into a boiling tube all at the same time, so I will get someone to assist me while doing so.
If the experiment goes on for a ridiculous time, I will cut it off. I don't think it is necessary to have the experiment go over three minutes, so I will cut it off then. Also, if the amount of gas goes off the scale I will stop it there.
It is important to keep the starting temperatures constant for all the reactions as this can affect the results by giving the particles more energy (and making it faster).
Analysis of Results.
From the experiment, I have found that an increased concentration of acid increases the rate of the reaction.
I think that the best way of displaying these results is by drawing a line graph. In it, I have used the average of the two sets of results. The pattern I can see is that when the reaction first starts, the reaction is fastest, from then on, the reaction slows. We can see this because the gradient of the curve is steepest at the beginning.
The cause of this curve is that at the start of the reaction, there is the most ammount of acid molecules that are colliding with the marble. (I can draw this from my initial hypothesis)
OBTAINING EVIDENCE
TABLE of RESULTS
Concentration of Acid. Time 10 20 30 40 50 60 70 80
0.5 15 20 25 28 30 32 34 36 37 38
0.5 14 22 28 33 38 41 44 47 48 50
1 28 48 58 67 79 83 93 97 100 105
1 20 40 54 64 73 81 86 92 99 103
2 40 60 76 90 100
2 38 55 74 89 100
3 30 44 70 85 99 110
3 30 62 90 110
4 7 115
4 30 65 87 110
During the experiment, I kept the starting temperature constant at 23 degrees.
I stop watch to time the experiment.
I wore safety glasses.
Time is in seconds. Concentration is in morality..
I repeated the experiment twice to make sure my results were reliable.
