- If the size of the reacting particles is decreased, there is more surface area available for reacting and so the speed of reaction increases.
- When a solution becomes more concentrated, the number of particles present in the solution increases.
- Increasing temperature increases the speed at which the particles move. Thus speeding up the reaction.
Factors effecting the rate of reaction
I am looking at the pros and cons of investigating each factor on the rate of reaction.
Catalysts
Pro- This speeds up the rate of reaction by helping bonds between atoms to break and form more easily. It is also reusable
Con- The problem with this would be it makes this an unfair experiment unless you carefully measure out the same amount of catalayse.
Temperature
Pro-Heating it would speed up the experiment, and keeping it cold would slow it down. This is because if you heat it up it makes the water particles collide and move about more breaking up the marble chips faster.
Con- Heating it is can be very dangerous and it could make the test tube explode.
Concentration
Pro- You can see a definite difference if you use different concentrations.
Con- It can be quite expensive using a large concentration of the chemical.
Surface area
Pro-Its inexpensive, practical and not dangerous.
Con-It is a little inaccurate if not measured in exact sizes.
Choice
I have chosen to test the rate of reaction on surface area. This is because of all the reasons above can get around the con by using roughly the same size chip.
Plan
Pre-test
I’ve carried out the pre-test using different quantities of calcium carbonate and different quantities of Hydrochloric acid. The quantities with long and most vigorous reaction will be the quantity I will use in the investigation because it will give me a good set of results.
Apparatus
Medium sized Calcium carbonate chips
Three Test tubes
Scales
Timer
Method
- Measure 5g of calcium carbonate and measure 20ml of Hydrochloric acid.
- Put the calcium carbonate in the test tube, pour the acid in and quickly start the timer.
- Observe every ten seconds the weight of the marble chips and acid. Stop when the same weight occurs four times in a row.
- Repeat steps 1-3 with 10g of calcium carbonate and 40ml of hydrochloric acid.
- Repeat steps 1-3 with 15g of calcium carbonate and 60ml of hydrochloric acid.
Results
5g and 20ml of hydrochloric acid–Fast reaction and not very vigorous.
10g and 40ml of hydrochloric acid-Long reaction and very vigorous.
15g and 60ml of hydrochloric acid-Long reaction and quite vigorous.
Conclusion:
This pre-test showed me that the best results to use in my investigation would be 10g and 40ml of Hcl. This was because this was the most vigorous and the longest results without wasting too much Hcl and Calcium carbonate.
Evaluation
This pre-test was quite accurate. There was only one problem, acid was loss to the spitting I will use cotton wool to cover the top. The reason I will not use a cork stop is this will prevent all gas escaping. I will use wool because this will let gas escape but not acid.
Prediction
I predict that the large marble chips are going to take the longest to diffuse. The medium a fair amount of time to diffuse and the smallest chips will be the quickest to diffuse. I know this by my theory on diffusion and the collison theory. I know that If the size of the reacting particles is decreased, there is more surface area available for reacting and so the speed of reaction increases.
Equipment
Small, medium and Large marble chips.
Conical flask
Electronic Scales
Measuring cylinder
Hydrochloric acid
Cotton wool
Method
- Measure 10g of Marble chips in small, medium and large.
- Place the flask on the scales and take away the weight.
- Pour the large marble chips in the flask.
- Measure 40ml of hydrochloric acid and pour
- Quickly put the cotton wool on top and start the timer.
- Observe weight every ten seconds. Stop observing when the same weight repeats itself four times.
- Repeat steps 2-5 but use medium marble chips.
-
Repeat steps 2-5 twice using small marble chips.
- Record all results in the table. Work out the averages of the small chips.
Diagram
Results
Analysis of Results
Conclusion
The rate of reaction should be longer for the small chips because more surface area for the hydrochloric acid to work on. The loss of mass is the largest in the big chips. However the loss in the medium chips is not as large as the small chips. The small chips loss of mass was consistent in the experiment. This is because the larger the surface area the faster the rate of reaction is. As you can see my results link back to my planning. In my planning it was said that if the size of the reacting particles is decreased, there is more surface area available for reacting and so the speed of reaction increases. This is true and matches up to my results.
Evaluation
My experiment worked extremely well in the plan but didn’t work as well when I did the whole experiment. My results were not as accurate as expected. The flaws in my experiment were probably due to the following factors:
- Timer wasn’t started at exactly the time the marble chips went in.
- To rectify this I will observe more carefully when to start the timer.
- The cotton’s mass was not taken and deducted at the end.
- I should next time take the mass of the cotton
- Hydrochloric acid was not measured out properly.
- I could maybe weigh the amount of hydrochloric acid used on some electronic scales.
- Lots of people were in the room and were all walking about. People could have knocked the table causing the mixture to be swirled around a bit. Making the results slightly unfair.
- I could possibly of done the experiment in a quite room on my own without distractions and lot’s of people walking about knocking the table.
- The Calcium carbonate chips were not all the same size.
- When choosing the chips I could of looked for similar sized chips to use so surface area was still the same.
However even with these factors taken into account the experiment gave me my expected results. So I presume that these flaws in my experiment did not really effect the results.
To further on my work I could look at how a catalyst would effect the rate of reactions. I could also look at all the other factor such as temperature and concentration and how they effect the rate of reaction.
