Does The Number of Drops of Catalyst Effect The Rate Of Reaction

Variables and Things that are kept constant

The variables are the number of drops of the catalyst, Copper Sulphate1 Drop,

2 Drops,

5 Drops,

7 Drops,

10 Drops and

15 Drops.

The things that are kept constant are the amount of zinc, the number of solution and the strength of the acid, mixing the distilled water and the 2M acids carefully to make 1M acids.

This is a fair test because the only thing that is changed is the drop of the copper sulphate and that is what was measuring. We will be repeating the experiment to get a better average.

The only thing that can make his test unfair is the pressure and the temperature, if we wanted to be more accurate we would put the reaction in a bath to keep the temperature constant as water heats up a lot slower than air so during the time it takes to do the experiment the heat will remain the same.

Diagram

Names and Quantities of the Solutions Used

I will use 50cm3 1M Sulphuric Acid, H2SO4.To get 1M acid solution you add 25cm3 of Distilled water and of sulphuric acid in either measuring cylinders or a graduated flask, which is more accurate.

I will use Copper Sulphate, CUSO4 as the catalyst. I will use the following amounts of catalyst:

1 Drop,

2 Drops,

5 Drops,

7 Drops,

10 Drops and

15 Drops.

Expectations

I would expect that the rate of reaction would go up as the no. Of drops increased as by the collision theory as the speed of the reaction goes up the more chance of collisions as they have greater power to hit into one another and the reactions will happen more frequently. I expect as the No. Of drops to double that the rate of reaction doubles also due to collision theory. These are the results I am hoping for.

Measurements

I will measure the amount of hydrogen collected during the experiment. I will measure the time it takes to collect 20 cm3 of hydrogen and I will use a gas syringe to collect the hydrogen. I will use the number of drops of catalyst as stated in the ‘Names and Quantities’ section and a teat pipette will be used to measure out the drops, it must be the same pipette as all pipettes give different drop sizes so to remain constant use the same teat pipette. I will mix the distilled water and the acid in a measuring cylinder.

What I will do to ensure my results are reliable

I will do the same experiment three times so the results are accurate and if I get an odd result the others will balance it out, in the end I will use the average. I will always use the same apparatus so everything is kept constant.

Results for Pilot experiment

In the real experiment I will work out the rate of reaction, to do this I will:

   1                  1                /sec or /s-1

 Time             secs

This is valid:  Amount of product                       =20cm3 of gas which is constant

                              Time                                                         time

Rate = 20                             1

          Time                       Time            =  Inversly proportional to time

Obtaining Evedence

Table Of Results

Analysing

The red dot indicates an anomalous result

Findings

The results in the end supported my original hypothesis, of course in lab conditions the results are not going to be perfect as the drops could have been different sizes and the zinc was not measured exactly. The general trend is that the line is basically straight and follow a pattern, because as the more drops of catalyst the more collisions between zinc and copper sulphate to form copper and zinc sulphate, the true catalyst of the reaction is the copper, the reaction between zinc and the acid particles react on the surface of the copper and so the more copper sulphate the more copper so the more chance that a reaction between zinc and copper sulphate on the surface of the copper as there will be a bigger surface area to react on.

Quantative Prediction

I predicted that if the amount of the catalyst doubled then the rate would double, that almost worked out and it was only out by about 1 second. I can prove this again by collision theory as if the amount of copper sulphate and therefore the amount of copper doubled then the rate of reaction would double as there would be double the surface area.

Evaluating

Were the results Good or Bad?

I think on the whole my results are fairly good as they follow the particular trend and there is a basic straight line on my graph as I expected.

How accurate were the results?

My results were not perfect as there was an anomalous result in the graph namely at 3 drops of copper. But the graph did show as the number of drops went up the rate also went up due to it being inversly proportional.

How Reliable were the results?

My results were reliable, I can say that because all of my duplications were fairly close to each other and so the avarage was very close to all of my runs.

How suitable was the procedure?

 The problems with the procedure are that the zinc was not measured to the highest accuracy so I would have very accurate scales and take time to get a perfect gram.The amount of copper sulphate could have varied as the teat pipette could have given different sized drops so I would make the experiment bigger and use measurements from a pipette filler. Also the temperature could have varied as it was not controlled, one idea to control this is to put it into a water bath and set it at a constant temperature, this would also keep the pressure constant.

What Caused The Anomalous result?

 I think the anomalous result was caused by the facts listed above, the temperature, pressure, amount of zincand the amount of copper sulphate were not kept constant.

Did I do enough readings

I think I have done enough readings as the trend of my predictions were there but I could have done a greater range. The only problem with that is I would have to dilute the acid again as the times were very quick for 15 seconds so it would be to awkward to collect if I did 30 drops of copper suphate it would have been to quick to record.

Could your results lead to any findings outside the range of results covered?

Yes I could as my graph is a straight line graph so I could extend it and look at maybe 40 or 50 drops and look at what the rate is for them

What additional relevant work could you do to extend your theory?

We chose to vary the amount of drops of catalyst but what you could vary is maybe whether the temperature, pressure, concentration of the acid or amount of zinc.