Also the heat energy, which is supplied to the atoms, is converted into kinetic energy and therefore the atoms move and collide with each other causing reactions. If you add more heat energy (i.e. increasing the temperature) then the atoms will have more kinetic energy and therefore move faster. If they are moving faster the rate of reaction increases because the atoms will collide more often and the reaction will speed up. This also means that there will be more successful collisions, as the atoms are colliding with a greater force.
Variables:
Whilst I am carrying out my experiment I will make sure that I carry it out fairly and accurately. I am going to do this because any incorrect readings that are taken will affect my results.
During my experiment I will try and keep the following factors the same:
- Concentration of hydrochloric acid: I will make sure that I use the constant amount of acid each time.
- Volume of acid: I will measure the volume of acid using precise measuring tools each time. There must also be no extra acid left in the beaker between the intervals of two experiments as it will lead to a false amount of acid in the beaker.
- Surface area of magnesium: To keep this constant I must use the same amount of magnesium each time and make sure that each strip weighs the same throughout the investigation.
One following factor that I will have to change during the experiment each time is the:
- The temperature of the acid: I will heat the acid until it has reached the right temperature for each test.
One factor that is not included in the variables but that I will keep the same is the working condition in which the experiment will take place and also the apparatus that have been used to carry out the experiment.
Apparatus:
To carry out my experiment I will need the following apparatus:
- Bunsen burner: to heat the acid.
- Gauze mat: to ensure the beaker does not fall onto the Bunsen burner.
- Tripod: to hold the beaker above the Bunsen burner.
- Safety mat: for safety whilst using heating equipment.
- Beaker: to heat the acid.
- Test tube: to carry out the actual experiment.
- Measuring cylinder (×2): to measure out the correct millilitres of acid and to measure the amount of gas collected from the experiment.
- Thermometer: to check the temperature of the acid.
- Timer: to measure the elapsed time.
- Water trough: to hold the measuring cylinder upside down into the water.
- Delivery tube: to carry hydrogen gas given off the experiment in the test tube to the water trough.
- Hydrochloric acid: 20ml oh hydrochloric acid for each test.
- Magnesium ribbons: 0.1g of magnesium ribbon for each test.
Readings and Measurements:
From the experiment I am going to take six readings. Each reading will be at a different temperature starting from 30ºC going up to 80ºC. At each range point I will take five readings which will be in minutes going up to five minutes of the overall time of each test. I will repeat the experiment twice so that I have two different sets of results. From these two sets I will get an average for each result.
I have chosen to go up to 80ºC because from my research I found out that after 80ºC, hydrochloric acid starts to evaporate. This means that if I take my readings further on I will loose some acid because of evaporation. If I do lose any acid before the experiment, one of my variables, which is the volume of hydrochloric acid, will change and therefore lead to an unfair test.
What I will be measuring in the experiment is the hydrochloric acid which I is going to be heated up, the magnesium ribbons and the hydrogen gas which is given off from the tests.
The measurement units that I am going to use are:
- ml: I will use millilitres to measure the hydrochloric acid from a measuring cylinder into a beaker and also to measure how much hydrogen gas I collect in the measuring cylinder from each test.
- g: I will use grams to weigh the magnesium ribbons so that I use the same amount of magnesium for each test.
Method:
Here is a brief account of how I carried out my experiment.
First of all I got all the apparatus that I needed to carry out the experiment. Then I poured 20ml of hydrochloric acid into a measuring cylinder and then poured it into a beaker. I put the beaker on top of the tripod and gauze mat and heated the acid using the Bunsen burner. I inserted the thermometer into the beaker as well. When the acid gets to the right temperature, I poured the acid into a test tube already set up with a magnesium ribbon inside. I had already set up the delivery tube and water trough so as soon as I poured the heated acid into the test tube I but put the delivery tube inside the test tube which already had a rubber bung to stop the gas escaping and started my timer. Then using the time, after each minute going up to five minutes I took a reading of how much hydrogen gas I had collected from the test.
I used this same procedure for each test in my experiment making sure that after each test the apparatus that I was using were ready and useable for the next test.
Diagram:
Here is a diagram of how I carried out my experiment:
Results:
These are the results I got from my experiment. The first table shows the results for the first experiment and the second table shows the results for the second experiment. The third table shows the average results of both of the experiments.
TABLE 1 – showing results of the first experiment
TABLE 2 – showing results of the second experiment
TABLE 3 – showing averages of both experiment results
Conclusion:
From my results I can see the obvious connection with temperature and
the rate of reaction. As the temperature increases so does the rate
of reaction. So going back to my prediction I can say that I was accurate in
the fact that I had predicted that as the temperature increases the rate of
reaction also increases. Also the amount of hydrogen gas formed at the
end of each test also increases as the temperature increases.
As the temperature of the hydrochloric acid increases the atoms inside
move faster as they receive more energy from the extra heat provided.
This means that the particles move faster, and they collide more often.
What it also means is that more collisions are successful as the particles
impact with a greater force and more bonds are broken.
Also the rate of reaction increased because the atoms are gaining more
energy. The atoms gain kinetic energy from the heat which is produced.
So if you increased the temperature you therefore, are increasing the heat
energy supplied to the atoms. This in turn increases the kinetic energy
and the atoms move faster. If the atoms are moving faster they collide
more often with each other and therefore, increase the rate at which they
react.
This means that I have one conclusion on the investigating the effects of
temperature on the rate of reaction between hydrochloric acid and
magnesium. That conclusion is:
Evaluation:
Looking at my result I can say that they are sufficient enough to draw up
the conclusion which I have made and that they do not seem to bring out
any extremely anomalous results. I have also noticed that the volume of
the acid decreases as it is heated. This maybe due to the fact that
hydrogen from the liquid evaporates from the solution. This may have
thrown off the accuracy of the investigation. However, the chance that
hydrogen evaporated is not as likely, as water. Because the hydrochloric
acid has been diluted and there is a significant amount of water, making
HCl less concentrated. However, at higher temperatures the water
might have evaporated, and caused the concentration of the acid to
increase.
On the other hand I still think I carried out my experiment as carefully as I
could making sure that all the test I took were fair. This is probably why
my results look satisfactory and do not bring out any extremely
anomalous results. From this I made out a good conclusion stating
the difference that the temperature of an acid makes to a reaction.
