In the experiment I predict that when the concentration of the acid is increased, the reaction will go faster, because in dilute acid there are not many acid particles. This means there is not much chance of an acid particle hitting a calcium carbonate molecule. There fore there will not be so many successful collisions.
E.g.
In a 2 molar acid there are twice as many acid particles than in a 1 molar acid there fore there will be twice as many successful collisions between the acid particles and the calcium carbonate molecules to produce twice as much carbon dioxide. The experiment will also go twice as fast.
Here the acid is more Here there are not as many
Concentrated – there are as many acid particles so
More acid particles in it. There won’t be as many
There is more now more successful collisions.
Chance of a successful
collision.
Method
I began by collecting all the necessary equipment for the experiment. This included mainly the equipment list. I then set the equipment up.
Once the equipment was ready I poured an unspecified amount of 0.5m acid into a beaker. I then poured the exact amount of acid required (30cm³) into a measuring cylinder. Having poured the correct amount of acid into the measuring cylinder I went to collect my calcium carbonate chips, to do this I placed a sheet of filter paper on the balance. I then reset the scale so that it read 0.0g; I then took a small amount of medium sized chips and placed them on the scale until it measured 3.0g. Once I had the correct amount of calcium carbonate chips I checked they were all roughly the same size. This is to ensure that all the chips have an equal coverer age of acid during the reaction. After weighing the chips, I begun to properly set up the experiment. I put the 3g of calcium carbonate chips in a collection tube, which lead into an inverse-suspended measur5ing cylinder. I then made a rough table stating the concentration of acid, the time interval (10s) and the volume of gas produced. When I had completed my table, it was time for reaction to begin. My chips were already in the collection tube, so I added the acid, placed the bung on top and began to record my results every 10 seconds. When the experiment finished, I checked my results for outstanding or uncommon results called anomalies. I did not have any, but to be sure I would have to wait for the results from my other experiments to see if the 1 molar was an anomaly on the whole. After finishing my experiment, I cleaned my equipment, re weighed some medium calcium carbonate chips (to mass of 3g) and got a small amount of 1.0 molar acid to put a beaker and then measured 3oml into a measuring cylinder. I then got all my equipment ready like I did for the fist experiment. When everything was ready I repeated the experiment exactly the same as the first time recording my results until I had matching results with all of the acid molars. Having all of my results I constructed a four tables:
- I was unable to record results in the 1.5 and 2 molar experiments because I didn’t have the equipment to record the amount of gas produced after 100 cm³.
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To record the results as accurately as possible I used a 100cm³-measuring cylinder to get the correct amount of acid, to put in the collection tube to produce the reaction.
- I used the electronic scales to get the correct weight of calcium carbonate chips, I also checked they were all the same size so that the chips would have an equal coverage.
Analysis
In the graph I had to use a line of best because the graph paper didn’t have enough gradients to create a big enough graph and get a curved line.
My graph proves that my results are correct as the 1 molar line goes up twice as steep as the 0.5 molar line. Also the 2 molar line finishes twice as fast as the 1 molar line. This is because in the experiments there were twice as many acid particles in the 1 molar acid than in the 0.5 molar acid and in the 2 molar acid than in the 1 molar acid. Resulting in the reactions being twice as fast, as there are twice as many acid particles which would produce twice as many successful reactions between the calcium carbonate chips and the acid particles. Producing twice as much gas.
Evaluation
To improve the experiment and get more accurate and reliable results I could:
- Use a measuring cylinder that recorded from 0cm³ to 100cm³ instead of 10cm³ to 100cm³.
- Use a syringe to get a more accurate measurement of 30cm³ of acid for the reaction instead of using a 100cm³-measuring cylinder.
What may have caused any anomalous reactions
- The concentration of the reactants. The more concentrated the faster the rate (in some cases the rate may be unaffected by the concentration of a particular reactant provided it is present at a minimum concentration.
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Temperature. Usually reactions speed up with increasing temperature ("100C rise doubles rate").
- Physical state of reactants. Powders react faster than blocks – because they have a greater surface area and since the reaction occurs at the surface we get a faster rate.
- The presence (and concentration/physical form) of a catalyst (or inhibitor). A catalyst speeds up a reaction, an inhibitor slows it down.
- Light. Light of a particular wavelength may also speed up a reaction.
My results were a good match as I was very careful to make sure I had all the correct measurements and shaped calcium carbonate chips. The one anomaly was probably due to an inhabiter, which slowed the reaction down quite a lot.
Further work I could do to provide additional relevant evidence to back up the experiment is use a greater molar value of acid to see if the results would match the results that I currently have. I could use a different size calcium carbonate chip possibly have the size of the ones I used to see if the experiment would go twice as fast.
