Preminary Study: -
I’ve tested using two molar Hydrochloric acid with Marble chips but I couldn’t even take the reading every
Bhaktipriya Nayan Kapadia- Chemistry coursework
Minute. The reason for this is that the concentration was too high. I then tried to use 5ml of Hydrochloric acid 5ml of water, which would decrease the concentration to one molar of Hydrochloric acid so then the reaction would be slower. This would mean I could take the reading every 30 seconds. This worked out in my trial so I obtained this for my final results.
Preminary Results: -
These readings show that I can take the reading every 30 seconds by diluting the acid to make the reaction a bit slower.
Variables involved: -
For this experiment I would expect to have 3 different variables (independent variable, Dependent variable and fixed variable), which would help me to plan and explain the experiment thoroughly.
Bhaktipriya Nayan Kapadia- Chemistry coursework
- The independent variable: (Thins you change)
The element that I will be changing in this experiment is the sizes of the marble chips (surface area). To see which size marble chips are the fastest.
- The Dependent variable: (things that you measure)
The things that I will be measuring in this investigation are the Volume of gas produced with, Marble chips reacting with Hydrochloric acid. Also I will be measuring the time in seconds.
- The Fixed variable: (things that you keep the same)
The things that I have chosen to keep the same in each individual experiment to keep it a fair test is to use the same amount of hydrochloric acid, water and mass of the marble chips. In this case I will use 5ml of hydrochloric acid, 5ml of water and 3 grams of marble chips.
Safety: -
Safety is an important aspect in every investigation, even if the experiment seems to be very harmless. This is why I’ll be taking this into consideration.
Bhaktipriya Nayan Kapadia- Chemistry coursework
I will be using Hydrochloric acid, so I will be careful that the solution doesn’t get to our eyes and body, because we are not fully aware of the damage it could do to us. So for safety reasons I will be wearing a lab coat to protect my skin and goggles to protect my eyes.
But other than that there will not be any big matter to be cautions of.
Equipment: -
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GOGGLES: - this will be used to protect my eyes.
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LAB COAT: - This will be used to protect my skin and cloths
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TEST TUBE: - This will be used for the reaction to occur in
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STOP WATCH: - This will be used to time the reaction on when to take readings.
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LARGE MARBLE CHIPS: - These will be used to react with Hydrochloric acid and water.
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MADIUM MARBLE CHIPS: - These will be used to react with Hydrochloric acid and water.
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SMALL MARBLE CHIPS: - These will be used to react with Hydrochloric acid and water.
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CRAMP STAND: - This will be used to hold the syringe.
- SYRINGE: - The gas will be produced from the syringe.
Bhaktipriya Nayan Kapadia- Chemistry coursework
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HYDROCHLORIC ACID: - This will be used for the marble chips to react in
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WATER: - This will be used to decrease the concentration.
Method: -
I plan to carry out this experiment by using all the safety issues and fair testing procedures to give me the most accurate set of results.
I plan to have a range of sizes for marble chips but the same mass. I will use sizes small medium and large. I will be using 5ml of Hydrochloric acid, 5ml of water and 3 grams of marble chips.
Once I have set up my apparatus I will measure 5ml of Hydrochloric acid and 5ml of water. I will then pour this into the test tube. Then I will get the stopwatch and quickly drop the marble chips and at the same time start my stopwatch. This must be done in a very short limit of time. From then on I must take the reading of the volume of gas produced in the syringe every 30 seconds. I must record the results in a table. The factors that affect my results are how quick my chips are put in and how quick the stopwatch has began. Although this is a factor that will affect the end results, and as long as the time is kept constant throughout then it should not matter too much. Tap water may have some things have some things in it so I used special water, which was provided.
Bhaktipriya Nayan Kapadia- Chemistry coursework
Results Table: -
A table to show how different size chips reacting with HCl
Bhaktipriya Nayan Kapadia- Chemistry coursework
Graph
A graph to show the difference between different sizes of marble chips.
Bhaktipriya Nayan Kapadia- Chemistry coursework
Conclusion: -
The evidence obtained from this investigation supports the prediction that I made: -
- “I predict that the smaller the particles the faster the reaction”
My prediction that I am correct as the smaller marble chips is the fastest reaction that occurred. My results
Table and graph show this. The graph shoes that:
- Curve 1 shows the base rate
- Curve 2 shows starts steeper than curve 1, which shows the rate started faster, so the pieces are smaller
- Curve 3 shows only half the amount of gas produced, so half the amount of carbohydrate may have been used
When a chemical reaction occurs the particles, which combine need, to meet with each other this is called “collision theory”. There are two types of bonds, when electrons cannot be gained or given away so they have to share electrons and this is called “covalent bonding”. When electrons become positively or negatively charged electrons are giving away or gaining electrons, this is called “ionic bonding”. In this case Marble Chips and hydrochloric acid would be sharing electrons. This is because hydrogen’s outer most shell is not full and chlorine’s outer most shell is not full. Therefore they would be sharing electrons which is called “covalent bonding”
Bhaktipriya Nayan Kapadia- Chemistry coursework
Evaluation: -
I think that the experiment went very well, there were no 'odd' results and they produced a good graph. My results are accurate as you can see from the graph and results table. They show this by showing that smaller molecules work faster but larger molecules work slower. In the science this has been proved and my results also show me this. The graphs and tables still show however the effects. I wanted because the rise in the amount of gas when the chips are smaller.
My results were made accurate because I used the same mass of Marble chips weather they were small or large, but in some cases I could not use only large or medium because they would be too lass in mass or too high so I had too add a small amount of small marble chips. This would have not been totally a fair test.
In this investigation I could have broken the large molecules instead of using the small marble chips. This way they would not be totally small. This could be improved if I would do this experiment again.
At the beginning of the experiment I decided that it might be interesting to see if the molecule size effects the reaction rate, I was interested to see if anything did change, so I thought for quite a while by using my own knowledge and wrote down what my theory was in my
Bhaktipriya Nayan Kapadia- Chemistry coursework
Prediction. I was very pleased when I discovered that my theory was correct.
If I had a chance to do this experiment again I would rather use a flask and measuring scale and see how much weight is lost. This would show how much carbon dioxide is lost from the mass. It would not be very confusing in looking at scale; as for a syringe it was quite difficult in taking the readings. But this measuring scale would be very easy too read from.
Bibliography.
- The GCSE Bitesize sites on Internet.
- Chemistry for AQA textbook
- My class notes
- Chemistry CGP book
