· Starting temperature of the acid
· Volume of acid used (cubic centimetres)
· Surface area of the magnesium
· Clean the magnesium with emery paper before experiment
· Length of magnesium
I will also have to make sure that the gas syringe is correctly connected and that it is placed quickly and tightly enough so that no hydrogen gas escapes.
The following factor that I will change is:
· The concentration of the acid
Apparatus and chemicals used
The apparatus and chemicals used during my experiment are as follows:
Chemicals
· 1M hydrochloric acid
· 1.5M hydrochloric acid
· 2M hydrochloric acid
· 2.5M hydrochloric acid
· 3M hydrochloric acid
· 3.5M hydrochloric acid
· Distilled water
Apparatus
· Measuring cylinder (100ml, 50ml, 25ml and 10ml)
· Conical flask (250ml and 100ml)
· Safety glasses
· Beakers (200ml and 90 ml)
· Test tubes
· Test tube rack
· Gas syringe
· Tile
· Paper boat
· Ruler
· Thermometer
· Scissors
· Glass rod
Safety
The things that I will need to do to keep my experiment a safe one for myself and other students around me are as follows:
· Wear safety goggles as I am using concentrated hydrochloric acid
· Care to eyes and the skin besides all the other people is always vital and necessary
· Care in using glassware since it is sharp when broken and can cut skin
· Safe disposal of reagents and laboratory chemicals
· Care when returning all used glassware and equipment at the end of the experiment
Preliminary work
The preliminary work that I will be conducting is to find out the optimum length of magnesium ribbon and the optimum volume of hydrochloric acid.
To do this I will be measuring out a volume of hydrochloric acid and a length of magnesium ribbon and reacting them together. If there is still some magnesium left over when it has stopped effervescing then I will have to increase the volume of hydrochloric acid.
If the reaction takes too long to finish then I will have to shorten the length of magnesium that I use, however if the reaction is too short then I will have to do the opposite and increase the length of magnesium that I use. The optimum rate that I am trying to find is a reaction that isn't too short but isn't too long, so I can get enough results to plot a good graph. I need to find the optimum volume of hydrochloric acid so that it is in excess after the reaction is over.
Apart from trying to find the optimum rate of reaction I also have to find out how to keep the temperature change down. This is because as the reaction is taking place the temperature will rise because the reaction is exothermic, and this could cause my results to be inaccurate as the temperature change will heat up the acid and give the acid particles more energy so they will move faster and collide with the magnesium with greater force causing more successful collisions per second.
To show that the hydrogen gas is not being given of from the water in the hydrochloric acid I will have to conduct a control experiment. This is when I will react magnesium ribbon with distilled water to show that there is no reaction between magnesium ribbon and water and that the hydrogen gas is evolving from the hydrochloric acid when it is being broken down into magnesium chloride and hydrogen.
Preliminary results
After my preliminary experiments I discovered that if I used 50cm3 of hydrochloric acid with 3 cm of magnesium ribbon then I could obtain some good results.
Also with these quantities the temperature change is kept to a minimum
Time (seconds) 5 10 15
Gas evolved for 1M hydrochloric acid (cm3) 4 7 11
Gas evolved for 2M hydrochloric acid (cm3) 18 24 24
Starting temperature (oC) End temperature (oC) Temperature change (oC)
22 25 3
As these results produced a reasonable volume of gas in a reasonable time these were the quantities of chemicals that I used.
I also used these quantities of chemicals because it kept the temperature increase to a minimum.
Method
1. Put on safety goggles
2. Collect clamp stand, clamp and boss
3. Collect conical flask and measuring cylinder
4. Collect stop clock
5. Measure out 50 cm3 of 0.0M hydrochloric acid with the measuring cylinder
6. Pour hydrochloric acid into the conical flask
7. Collect thermometer
8. Measure the starting temperature of the hydrochloric acid
9. Measure 3cm of magnesium ribbon
10. Clean the surface of the magnesium with the sandpaper
11. Drop the magnesium into the conical flask
12. Quickly place the rubber bung into the conical flask
13. Start timing with the stop clock
14. Record the amount of gas evolved every 5 seconds for 15 seconds
15. Measure the temperature of the solution after the reaction is over and measure the temperature change
16. Repeat steps 5 to 12 changing the concentrations of the acid
17. Repeat steps 5 to 15 to make sure that my results are reliable and reproducible
Results
Raw results
A table to show the results for test 1
Time (seconds) 0 5 10 15
Concentration (Molar)
0.0 0.0 0.0 0.0 0.0
1.0 0.0 4.0 7.0 11.0
1.5 0.0 10.0 20.0 26.0
2.0 0.0 18.5 24.0 24.0
2.5 0.0 29.0 29.0 29.0
A table to show the results for test 2
Time (Seconds) 0 5 10 15
Concentration (Molar
0.0 0.0 0.0 0.0 0.0
1.0 0.0 4.0 8.0 11.0
1.5 0.0 10.0 20.0 26.0
2.0 0.0 15.0 21.0 21.0
2.5 0.0 25.0 26.0 26.0
Processed results
Gas evolved in test 1 (cm3) Gas evolved in test 2 (cm3) Average gas evolved (cm3) Initial rate of reaction (cm3/s)
Concentration (Molar)
0.0 0.0 0.0 0.0 0.0
1.0 4.0 4.0 4.0 0.8
1.5 10.0 10.0 10.0 2.0
2.0 18.5 15.0 16.7 3.3
2.5 29.0 25.0 27.0 5.4
My processed results contain the results for the amount of gas that had evolved in 5 seconds for both tests then the mean average for both of them and then I calculated the initial rate of reaction.
Conclusion
My results table and graph show me that when I increase the concentration of the hydrochloric acid, the initial rate of reaction also increases.
Altogether I tested 5 different concentrations of hydrochloric acid. 0.0M, which was the lowest concentration of acid that I used, there was no reaction. 2.5M hydrochloric acid, which was the highest concentration that I used, produced the fasted rate of reaction. I repeated all 5 concentrations twice to be sure that they were reliable results and in all cases the higher the concentration the higher the rate of reaction. I had stated this in my prediction.
However I also stated in my prediction that if I doubled the concentration from 1M to 2M hydrochloric acid then the rate of reaction will also double. I have discovered that this is not the case.
Concentration (Molar) Test 1 Test 2
1.0 4.0 4.0
1.5 10.0 10.0
2.0 18.5 15.0
As you can see from this table as the concentration doubles then the rate of reaction approximately quadruples. My graph also shows that as the concentration doubles then the initial rate of reaction approximately quadruples.
When the concentration is 1M the rate = 4 = 0.8 cm3/second
5
When the concentration is 2M the rate = 16.7 = 3.3 cm3/second
5
I therefore conclude that:
1. The initial rate of reaction increase as the concentration of the acid increases
2. There is a fourfold increase in the rate of reaction as the concentration increases
3. As the concentration doubles the initial rate of reaction is approximately squared
My original prediction was that the initial rate of reaction would double as the concentration doubles. This was incorrect because it was not based on experimental evidence.
Evaluation
Was I precise in my measurements?
I feel that I was precise and accurate in recording measurements.
I measured the acid accurately by measuring the acid when the bottom of the liquid meniscus just touched the line on the measuring cylinder.
Liquid Meniscus
Measuring cylinder
I accurately cut the magnesium ribbon to the nearest millimetre with the ruler provided.
I measured the starting and the end temperature accurately with a thermometer to the nearest .5OC.
I accurately measured the volume of gas evolved to the nearest .5cm3.
I accurately measure the time that had elapsed to the nearest second with the stop clock.
Did I take enough readings?
Not enough concentrations were used for a good graph. I should have used concentration 3M acid ought to have been done but it was not known then that it was necessary and required.
The results that I did collect were reliable as I repeated the experiments twice to obtain good average results. My results were not only reliable they were reproducible.
Anomalous results
I obtained two anomalous results.
For concentration 2M there was 18.5cm3 of gas produced in test one, and in test two there was 15.0cm3, which is a 3.5cm3 difference:
= 23% error
For concentration 2.5M acid there was 29.0cm3 gas produced in test one, in test two the was 25cm3 gas produced, which id a difference of 4cm3:
= 16% error
These errors both occurred in the first run, when the technique and practical skill had not been perfected over a large number of experiments. The more times an experiment is preformed then the more accuracy and skill the student acquires. At higher concentrations there is more heat evolved which gives a larger volume error, since gases have a larger volume at higher temperature.
Another reason for these anomalous results is that the plunger on the syringe may have been sticking on the barrel after a lot of runs, which would have given me lower readings.
Improvements to my procedure
Improvements to my experiment are that I could stop the syringe plunger sticking by applying a thin coating of Vaseline to it.
I could also use a monometer to be sure that the atmospheric pressure inside the syringe is the same as the pressure outside of the syringe.
Monometer Gas Syringe
To be sure that the pressure is the same inside the syringe as outside the syringe the water levels in the monometer must be level.
The last improvement to my procedure is that I should check for gas leakages where the bung is placed into the conical flask, a smear of Vaseline would help me do this.
Further work
There are several things that I could do for further work. The first is to find out what the initial rate of reaction would be for concentrations 1.25M hydrochloric acid and 1.75M hydrochloric acid as it would be interesting to see how the rate increases compared to 1M hydrochloric acid.
Another experiment that I could do is change the type of acid that I use.
I could use sulphuric acid. This is a dibasic acid and its molecular build-up is H2SO4 and hydrochloric acid is 2HCL, because of this I would obtain different results. I could also use phosphoric acid, which is a tribasic acid, and its molecular build-up is H3PO4, I would also obtain different results if I used this type of acid. Nitric acid is a monobasic acid but its molecular build-up is HNO3, which is very similar to the molecular build-up of hydrochloric acid so the results that I would obtain from using this acid would be similar to the ones I already have, so I would not use this for any further experiments. The reason I could use a different type of acid for any further work is to find if the is a difference between them if their molecular build up is different.
I could also use the less reactive metals of the reactivity series (zinc, aluminium, iron and lead) that way I could find the initial rate of reaction at 5 seconds for the higher concentrations of acid like 3.0M or 3.5M and I could find there relative activity.
Bibliography
I obtained most of the information that I needed for my experiment form my teacher and exercise book. I also obtained information from several science textbooks and computer encyclopaedias. I obtained a small amount of information from the Internet.
Reaction between HCl and Mg
In the reaction between hydrochloric acid and magnesium ribbon, the hydrochloric acid will dissolve the magnesium and produce hydrogen gas. All chemical reactions involve reactants which when mixed may cause a chemical reaction which will make products. In my experiment the reactants are hydrochloric acid and magnesium ribbon. The chemical reaction takes place when the magnesium ribbon is dropped into the hydrochloric acid. The products that are formed during this reaction are hydrogen gas and magnesium chloride. The formula equation for this experiment is:
Mg + 2HCl (r) MgCl2 + H2
Magnesium + Hydrochloric acid (r) Magnesium Chloride + Hydrogen
The rate of reaction between the product and the reactant will increase or decrease depending on certain factors. The factors that may affect the rate of reaction are:- temperature of the Hydrochloric Acid, mass of the magnesium ribbon used, concentration of the Hydrochloric acid, surface area of the magnesium ribbon used
All of these factors will change the rate of reaction because of the Collision Theory. This is a theory that is used to predict the rate of a reaction. The Collision Theory is based on the idea that for a chemical reaction to take place, it is necessary for the reacting particles to collide with each other with enough energy to break or form new bonds between the other particles, which is called a successful collision. If when they collide and they do not have enough energy to break or form new bonds then they will simple bounce of each other, causing an unsuccessful collision.
Scientific Knowledge
"When a chemical reaction occurs, the particles which combine need to meet up with each other (collide) so that they can swap or share electrons. If you want to speed up a reaction, you need to get these particles to hit each other more frequently." (www.revise.it)
? ?
" If the solution is made more concentrated it means there are more particles of reactant knocking about between the water molecules, which make collisions between the important particles more likely." (GCSE Double Science Revision Guide)
Method
Fair Test
In order to keep my experiment a fair test I will have to make sure that I keep the following factors the same:- volume of acid used (cubic centimetres), surface area of the magnesium, length of magnesium. I will also have to make sure that the gas syringe is correctly connected and that it is placed quickly and tightly enough so that no hydrogen gas escapes. To make sure that all my results are as accurate as possible I will do each experiment three times and then take an average to prevent any anomalous results affecting the end conclusion in a big way.
Safety
The safety of this experiment is very important. The things that I will need to do to keep my experiment safe for myself and other students around me are as follows:- Wear safety goggles as I am using hydrochloric acid which can irritate the skin, Care to eyes and the skin besides all the other people is always vital and necessary, Care in using glassware since it is sharp when broken and can cut skin. Safe disposal of reagents and laboratory chemicals, Care when returning all used glassware and equipment at the end of the experiment
Plan
The experiment will be done using the equipment shown above. The acid will be measured in a measuring cylinder and then put into a conical flask. The water (if necessary) will be measured in the same way and added to the same conical flask as the acid. When I have set the gas syringe up in a clamp ( see diagram), I will cut a piece of magnesium ribbon to 5cm long. To make sure that all the gas given off is collected, I will ask some-one else to start the stop-watch as soon as the magnesium ribbon is in and the bung to the conical flask placed in the top. I will then time for 2 minutes and take a reading of the gas every twenty seconds. I will use six concentrations for this experiment and they will be:-
25ml acid : 0ml water
20ml acid : 5ml water
15ml acid : 10ml water
10ml acid : 15ml water
5ml acid : 20ml water
0ml acid : 25ml water
I will record the results in a table like the one shown below:
AMOUNT OF GAS COLLECTED
Time (s) Experiment 1
(ml) Experiment 2
(ml) Experiment 3
(ml) Average
(ml)
20
40
60
80
100
120
Prediction
I predict that the higher the concentration of the acid, the faster the rate of reaction will be. I predict this because I know that the higher the concentration of the acid, the greater the number of acid molecules present in that volume. This means that there are more acid molecules colliding with the particles on the surface of the reactant ( magnesium) thus increasing the rate of reaction.
What factors affect the rate of reaction between magnesium ribbon and hydrochloric acid?
GCSE CHEMISTRY COURSEWORK
This chemistry coursework requires an investigation to see how long it takes for magnesium ribbon to be eaten away by hydrochloric acid.
Before starting the investigation, I decided to do some research about magnesium and hydrochloric acid.
Magnesium is a light, shiny grey metallic element, symbol Mg, atomic number 12, found in group two in the periodic table. It is quite reactive giving vigorous reactions towards acids. It is one of the alkaline earth metals, and the lightest of the commonly used metals. It is used in alloys, flash photography, flares, fireworks and flash bulbs because it burns vigorously in air with a bright white light. Magnesium reacts with steam to release hydrogen and it also burns in carbon dioxide gas.
Hydrochloric acid, HCl, is a solution of hydrogen chloride (a colourless acidic gas) in water. The concentrated acid is about 35% hydrogen chloride and is corrosive. The acid is a typical strong, monobasic acid forming only one series of salts, the chlorides. Like most acids, it releases hydrogen ions when it is added to water and certain metals, and has a pH of less than 7. Hydrochloric acid is a common laboratory acid.
Extracts from: a chemistry coursework from an Internet source and
The HUTCHINSON Dictionary of SCIENCE second edition.
Before looking at the factors that can alter the rate of reaction, we must consider what happens when a reaction take place.
First of all, the particles of the reacting substances must collide with each other and, secondly, they need a certain amount of energy to break down the bonds of the particles and form new ones. This energy is called the activation energy or Ea. If a collision between particles can produce sufficient energy (i.e. if they collide fast enough and in the right direction) a reaction will take place. Not all collisions will result in a reaction.
The investigation could be done using one variable and therefore have a set of results which were related in some way. The variables that could be used are:
1. Concentration
2. Particle size/surface area
3. Pressure (for reactions involving gas)
4. Temperature
5. Light
6. Presence of a catalyst.
These variables can be used because:
1. The more concentrated the reactants, the greater the rate of reaction will be. This is because increasing the concentration of the reactants increases the number of collisions between particles and, therefore, increases the rate of reaction.
2. When one of the reactants is a solid, the reaction must take place on the surface area of the solid. By breaking up the solid into smaller pieces, the surface area is increased, giving a greater area of collisions to take place and so causing an increase in the rate of reaction.
3. When one or more of the reactants are gases an increase in pressure can lead to an increased rate of reaction. The increase in pressure forces the particles closer together. This causes more collisions and increases the rate of reaction.
4. An increase in temperature produces an increase in the rate of reaction. A rise of 10º C approximately doubles the rate of reaction. When a mixture of substances is heated, the particles move faster. This has two effects. Since the particles are moving faster they will travel greater distance in a given time and so will be involved in more collisions. Also, because the particles are moving faster a larger proportion of the collisions will exceed the activation energy and so the rate of reaction increases.
5. The rates of some reactions are increased by exposure to light. Light has a similar effect as temperature because it produces heat.
6. A catalyst is a substance, which can alter the rate of a reaction but remains chemically unchanged at the end of the reaction. Catalysts usually speed up a reaction. A catalyst, which slows down a reaction, is called a negative catalyst or inhibitor. Catalysts speed up reactions by providing an alternative pathway for the reaction, i.e. one that has much lower activation energy. More collisions will, therefore, have enough energy for this new pathway.
Extracts from: Letts Study Guide, GCSE CHEMISTRY.
All this information is relevant to my investigation, as I now know what would happen to the molecules when using different variables. It also makes it easier to decide what variable I am going to use in this circumstance.
I decided to use the concentration of acid as my variable. I used 5 different strengths of hydrochloric acid. These strengths would determine the rates of reactions. I decided to measure the acid in millilitres. I predicted that the higher the concentration of the acid, the faster the reaction between magnesium ribbon and the hydrochloric acid. This would be because there were more acid molecules to react with the magnesium ribbon. I decided that I would do 5 experiments and the different concentrations of hydrochloric acids were:
v 1.0 molar
v 1.25 molar
v 1.50 molar
v 1.75 molar
v 2.0 molar
Before doing the actual experiment I decided to do some preliminary work. These were to tell me the details that I would need to know for my investigation to be successful. I saw from these preliminary investigations that the magnesium ribbon started to react with the hydrochloric acid the moment that I dropped it in. I decided that it would be a good idea to start timing the second that I dropped it in. When the ribbon had been eaten away by the acid, it stopped fizzing. I decided that I would stop timing the second that the fizzing stopped. I discovered from my preliminary experiments that when I used a low concentration of hydrochloric acid, for instance, 0.25 molar, it took a long time for the magnesium ribbon to be eaten away. I decided that it would be impractical to spend time on the following strengths of hydrochloric acid:
v 0.25 molar
v 0.50 molar
v 0.75 molar
This was because they were the three slowest strengths of acids available to react with the magnesium ribbon over a period of time. I also learnt from my preliminary experiments that it was sometimes quite difficult to stop timing on the exact moment that the fizzing stopped. I decided therefore that I would carry out each of the 5 experiments three times and find the average time as this would result in a more accurate figure.
When the magnesium ribbon reacts with the hydrochloric acid, magnesium chloride is formed. I wrote down the equation to show this:
Magnesium + Hydrochloric acid = Magnesium Chloride + Hydrogen
Mg + 2HCl = MgCl + H
The equipment I needed for the investigation were:
v Magnesium ribbon- 15 pieces, 1cm long and weighed 0.01g
v Hydrochloric acid - 30 ml of 1.0 molar
30 ml of 1.25 molar
30 ml of 1.50 molar
30 ml of 1.75 molar
30 ml of 2.0 molar
v Test tubes - 5
v Test tube rack
v Stop clock
v Pipette
v Measuring Cylinder
v Thermometer
v Safety goggles
I decided to do 5 experiments, three times each, using all the information that I gained while I was doing my preliminary experiments.
To ensure a safe experiment and working environment I needed to have at least 1 meter squared of working space around me, wear safety goggles at all times when using acid, use a test tube rack instead of holding the test tubes, secure all equipment and make sure that all the equipment were fully functional and not damaged.
To make the experiment a fair test I used the same amount of acid for all experiments, only changing the concentrations. I used the same size of magnesium ribbon and weight (approximately 0.01g). I also started the stop clock when the magnesium touched the acid and stopped it when the magnesium stopped fizzing for each experiment. I always washed out the test tubes when an experiment had finished so the different concentration wouldn´t get mixed together causing strange results.
First I measured out the amount of hydrochloric acid using the measuring cylinder. I used a pipette to pour the acid into the measuring cylinder as to be accurate. I needed 10 ml of acid in the cylinder and poured it into a test tube. I then put a thermometer into the test tube for 1 minute to check the temperature. I did this to see if the experiments with the same strength of acids affected the rate of reaction if there was a change in temperature. I then got a piece of magnesium ribbon about 1 cm long weighing 0.01g and dropped it into the acid and started timing the moment that the magnesium ribbon touched the acid solution. When the magnesium ribbon stopped fizzing, I stopped the clock and recorded the number of seconds (rounded up to nearest second) taken for the reaction from start to finish.
I made a table to record my results in. The table is shown below.
Experiment Strength of hydrochloric acids in 10 ml No. of Mg ribbon pieces (0.01g) Test 1 secs. Temp Test 2 secs. Temp Test 3 secs. Temp AverageSecs.
1 1.0 molar 1 151.0 18 ºc 141.0 18 ºc 117.0 18.4ºc 136.3
2 1.25 molar 1 81.0 17 ºc 76.0 17.5ºc 74.0 18 ºc 77.0
3 1.50 molar 1 58.0 17.5ºc 56.0 18 ºc 56.0 18 ºc 56.3
4 1.75 molar 1 50.0 18 ºc 41.0 18º c 31.0 18 ºc 40.7
5 2.0 molar 1 20.0 19 ºc 22.0 19 ºc 16.0 21 ºc 19.3
To calculate the average time that it took for the magnesium to be eaten away by the acid, I did the following calculation:
Test 1 + Test 2 + Test 3 = Average time
3
As I already have mentioned, I used a measuring cylinder to make the measurements and used a pipette for further accuracy. I did each experiment three times so I would be able to calculate averages and thereby get more accurate results. I recorded the results in seconds instead of minutes in order to obtain more precise results. I used a stop clock instead of a 24-hour clock so I could look at the milliseconds and round it up to the nearest second, which made the results more exact.
It was noticeable, when looking at the results table, that the more concentrated acid had a faster rate of reaction than the less concentrated acid. This was probably because there are more particles in a concentrated acid and therefore more collisions will occur. For instance, 1.0 molars´ average time, 136.3 seconds, is longer than 2.0 molars´ average time, which was 19.3 seconds.
I made a graph to show the results.
The graph above supports my original prediction of: the more concentrated the acid the faster the rate of reaction because it shows the time difference between the different strengths of acids. In a higher concentration there are more acid particles to react with the magnesium ribbon and therefore it is eaten away faster.
I conclude that changing one factor does have a significant effect on the rate of reaction as we have seen.
Looking at the set of results obtained, you can clearly see that they all follow the expected pattern. This is pattern suggests that the reaction rate increase when the concentration of the acid increases because if you increase the concentration of the acid you are introducing more particles into the reaction which will in turn produce a faster reaction because there will be more collisions between the particles which is what increases the reaction rate.
The evidence I have been able to gather from this investigation seems to lead to a quite firm conclusion. I might not have been able to find the exact speed of the reactions but the pattern seems to be correct as I have repeated readings three times and as it agrees with the information I have researched.
I used the variable of concentration, which seemed to be of a good choice as it would show the results of how more acid molecules reacting with magnesium, would result in a faster reaction.
There will always be ways in which you can improve your investigations and the same thing goes to my investigation.
I found it very hard to measure out the exact number of millilitres for the acid even though I used a pipette and I was also in a hurry. If I was to redo this investigation I would put some more effort into measuring the acid. I could have used the wrong concentration of acid by accident and that would have affected the speed because there would have been fewer or more acid particles to react with the magnesium ribbon. Next time I do this experiment I would try to remember which acid I am using so it doesn´t get mixed up. Every time I washed a test tube or a measuring cylinder, I did not dry it before using it. This may have affected the rate of reaction, as water would dilute the acid. To improve my results, I could dry the test tubes and the measuring cylinder after they are washed to prevent diluted acids. The size and weight of the magnesium would have affected the rate of reaction. The experiment could be improved by measuring, adjusting and weighing the magnesium ribbons so they all are the same size and weight. I also found out from background information, that the magnesium ribbon is covered with a whitish deposit. This deposit was magnesium oxide where the magnesium had reacted with the air. I would imagine that some pieces had only a little of this oxide and some had a lot. The pieces of magnesium ribbon that did not have much oxide on them reacted faster than those with a lot. To improve my results, I could clean the magnesium oxide of all the magnesium pieces using some sandpaper, and this would mean that the acid would not have to eat through the magnesium oxide before reacting with the magnesium. In my investigation I also measured the temperature to see if there would be any change in the rate of reactions. From my results it was noticeable to look at each experiment and see how the temperature had affected the rates of reactions. For instance, if we refer back to the table on page 5 and look at experiment 5, test three is slightly faster than test 1 or test 2 because it has a temperature of 21º, where as the other two tests both have a temperature of 19º. To improve my investigation I could assure that the temperature was constant all the time. I could also do more readings to get nearer to a more accurate result.
In my investigation I used concentration as my variable. To improve my investigation further, I could use other variables such as, surface area, temperature, pressure for gas, and a presence of a catalyst.
These variables would hopefully prove that they all help speed up a chemical reaction.
