Chemical reactions are greatly dependent on temperature. As the temperature goes up so does the rate of reaction. A simple 10 degrees Celsius rise wills often double the rate of reaction. The particles move about faster so they are more likely to collide. They also have more energy so when they do collide it is more likely to result in an effective collision.
The concentration plays a big part in chemical reactions. I am told that when the concentration is lower the time of reaction is lower, and to the opposite, when the concentration is larger the reaction time is faster. It is this variable that I have decided to study.
Formula:
Calcium carbonate + hydrochloric acid → Calcium chloride + Carbon dioxide +
CaCo3 + 2HC → Ca2 + CO2 +
Water
H2O
Aim:
Investigating the factors that affect the rate of a chemical reaction, In particular concentration.
Method:
- To start our experiment we collected and set up the apparatus (see diagram)
- We filled the water bath up with up with water then the burette with water to
- We attached the burette to the retought stand
- We turned the burette upside down and placed it in the water bath making sure that the burette had no air bubbles in it
- We then carried out a number of pre tests to find out a good mass of CaCo3 (calcium carbonate)
- We knew that we had the right amount of CaCo3 when gas was collected on the minimum amount of Hydrochloric acid (0.1 M) and no gas was lost on the maximum (1 M)
- With our apparatus in place and our pre test complete we could then put in the required mass of CaCo3 in the required strength of acid
- As soon as we put the CaCo3 in the acid we placed the bung on top, timed for 500 seconds then recorded the gas released in to a table
Equipment
- Retaught stand
- Water bath
- Conical Flask
- Burette
- Bung
Diagram
Fair Testing
These are some of the factors that could affect the rate of reaction:
- Surface area
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Temperature
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Mass of carbonate.
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Time
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Stirring it
- No catalyst
So to keep my test fair I will keep all the above continuous
Prediction:
I predict that the higher the concentration of hydrochloric acid the quicker the rate of reaction and the more gas to be collected
Hypothesis:
I know the following will happen because I have scientific knowledge to back up my theory. In the book New Modular Science it says that by increasing the concentration of dissolved reactant or the pressure of the gas mixture the particles are more likely to of coiled. This their for backs my idea.
It also tells me in Chemistry for GCSE’s by E.M Ramsdon ‘If the acid concentration is doubled, the speed doubles’.
Acid conc.
This is because ions are closer together in a concentrated solution. The closer they are together the more often the ions collide. The more often they collide the more chance they have of reacting. This also backs my theory.
Variables:
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Surface area- I know that the larger the surface area the faster the rate of reaction and the smaller the surface area the slower the rate of reaction. The following results (taken from Chemistry for GCSE) show that the smaller the smaller the particles of calcium carbonate, the faster the reaction time is
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Temperature- temperature affects the rate of reaction, as the particles are heated they gain energy, as they gain energy they are more likely to ‘bump into one another’ causing a chemical reaction
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Mass of carbonate-If you have more carbonate then there is more chance of the acid reacting with it, for example, if you tear the corner of a piece of paper off and put it on the floor then bring a class of 30 in it is less likely to be stood on than if you ripped the whole piece of paper up and place it on the floor.
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Time-the more time given, the more time there is for the reaction to take place
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Stirring it- If you stir the combined CaCo3 and the 2HC then in affect you are giving the particles energy, and once again the more energy given to the particles the more likely a reactions to of taken place.
Readings;
I will take my readings from 1 molar down to o.1 taking small incremental steps of 0.10 molars each time. We will record how much gas is collected in 500 seconds. We will also measure of CaCo3 at the beginning and at the end.
Using science to plan my procedure:
As I now know ‘if the acid concentration is doubled, the speed doubles’ as quoted from Chemistry for GCSE’s. This means that as the acid strength rises so the reaction time becomes greater, Because of this information I decided to make small incremental steps of 0.10 Molars this will their for show the increase of reaction time more clearly, it will also make my results more accurate.
I also knew from my pre test to use 0.75g of CaCo3 this mass will be enough to collect gas on the smallest concentration (0.1M) and so that no gas is lost on the strongest concentration (1.0M).
Pre Test
No gas is aloud to escape the burette but yet the mass of CaCo3 must be large enough to collect some gas on the smallest concentration.
I carried out a number of experiments by changing the mass and volume of chalk and this is what my pre test results proved:
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Concentration: Max 1.00 Molars
Mass of CaCo3: 0.75g
Volume of 2HC: 4cm
Mass of CaCo3:0. 75g
Volume of 2HC: 4cm
Book references:
Chemistry for GCSE’s
New Modular Science for GCSE’s
Obtaining:
Results:
Hazards:
We didn’t have many hazards as we were not dealing with any particularly dangerous substances, but the ones we did have were:
- Being careful with the acids as it is corrosive/ an irritant
Equipment for accurate readings:
So that we got accurate results we did our results on the computer. This gave us precise readings that had not been affected by any of my variables.
We also used a burette which gave us more accurate results as we could clearly see and make sure that there were no air bubbles in there. The burette also gave us clearer results as we could take our readings more accurately than if we had of used something like a measuring cylinder for example as I have done in a similar previous experiment
Odd results:
I have no odd results, my prediction was right
Analysis:
What I’ve found out:
From my results and the shape of the line on my graph I have found out that my prediction was right: the larger the concentration of hydrochloric acid the more gas collected.
What happened?
As the concentration doubled so did the rate of reaction.
This is because ions are closer together in a concentrated solution. The closer they are together the more often the ions collide. The more often they collide the more chance they have of reacting.
Accurate prediction
My prediction was accurate; I know this because my results agreed with my prediction.
Nothing different happened to what I expected, I think this was because I had a good hypothesis and from this scientific knowledge that I gained I could accurately predict.
Evaluation
Good method?
I think that I had a good method, as it was clear and accurate. The reason I think this is because I feel that by following my method even if you had never done the experiment you would come out with a set of accurate results
Good Results?
I think I have a very good set of results they are clear and accurate and clearly show that I predicted right. I had no odd results, which also showed that the test was done accurately, and that none of my variables were involved in my experiment.
Using my method for accurate results:
To make my results and any one who followed my method in the future more accurate I made sure that I mentioned things like making sure there’s no air bubbles in the Burette, how to actually set the apparatus up rather than just guess by looking at the diagram and mentioning things like we timed for 500 seconds.
Things that may of made my procedure less reliable:
- Temperature
- Surface area
- Stirring
- Mass of Carbonate
All of the above could of affected my experiment slightly with out them happening on purpose for example, there’s no way that I could of got the mass of carbonate exactly right, I could change this by measuring the weight of the carbonate
Reliable results:
To make sure that I ended up with reliable results I took small incremental steps of 0.10 molars, I could have repeated the experiment 3 times and than worked that average but I thought this to be the best way
Conclusion
I conclude that by doubling the concentration you double rate of reaction. I know this as the scientific Knowledge that I have backed my prediction and my prediction was right.
Method of improving work:
I could improve my work by not only taking small incremental steps but by testing the same concentration 3 times and then averaging it out
Carrying on the investigation
I could carry this investigation on by maybe finding the rate of reaction between Calcium carbonate and hydrochloric acid when one of my variables becomes the factor to study i.e. surface area.