reaction it will also be quicker in some situations but if they are too hot they would be reacting good I also found out the most efficient temperature which the particles work best at which is 37o
If the particles were at a cold temperature they wouldn’t really be speeding around and colliding with enough force to complete a successful collision, they will still be moving around but if any collisions occur it wont affect the reaction that much.
Surface Area (Particle Size)
Too have successful reactions and good collisions I think you should have many small particles instead of fewer large particles because there is more surface area on the smaller particles than the larger one. You can see this by looking at the following diagram:
As you can see there is only 4 directions in the big particle that the other particles can collide with.
As you can see there are 16 directions in the other 4 particles that can fit into the larger one that other particles can collide with.
So as conclusion you can see the small particles have more of a surface area and will be more efficient to have in the reaction.
Catalyst
Use of a suitable catalyst means the particles may react even if they collide with only moderate energy. This means more often collisions are likely. Some catalysts work because one of the particles is fixed to a surface. This makes the chance of a collision more likely. More collisions mean a more successful reaction so this basically means that some particles stick to the catalyst and stay still and wait for other particles to collide with them.
Scientific Knowledge
There is a minimum amount of energy
which colliding particles need in order to react with each other.
If the colliding particles have less than this minimum energy,
then they just bounce off each other and no reaction occurs.
This minimum energy is called the .
The faster the particles are going, the more energy they have.
Fast moving particles are more likely to react when they collide.
You can make particles move more quickly by heating them up
(raising the temperature).
(I got this piece of info from www.revise.it)
Fair Test
What I plan to do to make it a fair test is to always use the same amount on magnesium (a 3cm strip) and the same amount of hydrochloric acid (25ml) the only thing I will change will be the concentration of acid.
Prediction
Here is my prediction of the variables that will make up the best reaction.
Concentration…………………………………………………………………….…… The highest
Temperature………………………….… The most efficient for the particles (37o)
Surface Area (Particle Size)…….... Small Particles = Larger Surface Area
Catalyst………….……………………………….….. Includes a catalyst (magnesium)
A High Concentration + 37o Temperature + Many small particles + A Catalyst Present = A fast Reaction.
The concentration must be high so there are more particles confined to less space so the more particles would be in a certain space that will cause many more constant collisions.
The temperature must be the most efficient (37o) which the particles work best at so the particles would be moving around at top speed and colliding with the best possible force.
The surface area (particle size) I think would have to be small particles because lots of small particles hold more surface area than big particles which basically means there is more area for the other particles to collide with.
The catalyst would have to be present for helping the reaction speed up.
In my conclusion: The 2.5m Acid would be the quickest to finish the reaction because the higher the concentration the quicker the reaction will finish.
Extended Prediction: When the hydrochloric acid reacts with the magnesium it will form a solution called magnesium chloride and Hydrogen will be given off.
Preliminary Tests
There were 3 experiment methods of doing this experiment:
- Burette Method
- Syringe Method
- Top Pan Method
Burette Method
What happens is the hydrogen goes up the tubing and gets released into the burette and becomes a bubble of hydrogen and when it get to the top it gets released from bubble form and gets stuck at the top and then the water beneath it gets pushed out by pressure.
Advantages:
Disadvantages:
- The bubbles might cause a blockage
- A tube might come loose
- Takes a long time to set up
Results:
Syringe Method
What happens is the hydrogen goes up through the tubing and then goes into the syringe and as the hydrogen increases it makes the syringe move by pressure force.
Advantages:
Disadvantages:
- Might get a stiff syringe
- Quite hard to take the readings
- A tube might come loose
Results:
Top Pan Method
You will have to measure the whole beaker of hydrochloric acid and magnesium including the glass beaker and then when the reaction is finished you see how much weight it has lost and take that away from the original weight and that’s your measurement of hydrogen.
Advantages:
- It is quite easy to set up
- Experiment is quick
Disadvantages:
- Might be Insensitive scales
- Might not read on 2+ significant figures
Results:
Test analysis
We have chosen the “Syringe Method” because the results seem less jumpy than the other experiment (Burette Method) and the experiment was quite easy to complete but the other experiment we had problems getting it to work (Burette Method).
Syringe Method
How to set it up
Its quite simple all you do is set up a clamp stand so it is holding the syringe as straight as possible but don’t tighten it too much as you might break the plastic. Attach the orange plastic tubing from the syringe to the orange bung on top of the beaker and you have it set-up and get your stop clock ready.
Measurements
We used 5 different concentrations of Hydrochloric Acid and we used a 3cm strip of magnesium for each concentration and we will time the reaction for 120 seconds because we might be able to get all of the hydrochloric acid concentration to finish their reaction then we could get a much more accurate average.
Measurements for each experiment:
25ml of Hydrochloric Acid x concentration
3cm strip of Magnesium
We will time for 120 seconds each.
We are going to do the experiment for each concentration 3 times to make sure that we have not accidentally done 1 wrong if so we will be able to see because we could just look at the others and see if they are similar. We will then take an average to get a clearer result that is easier to read and work out which reaction finished first.
Method
Here is a step-by-step detailed description of how we are going to do our experiment:
1. Measure the hydrochloric acid and cut the magnesium to size and remember try to be as accurate as possible. The measurements are as followed:
Hydrochloric Acid = 25ml
Magnesium = 3cm strip
2. Put the hydrochloric acid inside of the glass beaker and be careful not to spill any otherwise you will have to re-measure and try not to make the hydrochloric acid touch the sides of the beaker.
3. Carefully drop the magnesium in and try to drop to the middle of the beaker as possible and put the lid on as quickly as possible but also carefully to avoid a spillage (to stop any Hydrogen escaping).
4. Start the stop clock as the cap is put on it has to be immediate.
5. Take the syringe reading every 10 seconds for 120 seconds so you have 12 results and write them in table format and if you accidentally miss a result just leave it out and not guess it cause these figures will be increasing at a rapid rate.
6. Then take the lid off and empty the acid and wash it ready for the next concentration of acid.
7. Finally wash your hands.
Analysis
Looking back at the variables all of them would change a reaction quite easily but the only one I was changing was the concentration of hydrochloric acid. I had stated the higher the concentrated the quicker the reaction would finish in my prediction and this has proven to be true.
In my prediction I said, “The 2.5m Acid would be the quickest to finish the reaction because the higher the concentration the quicker the reaction will finish.” so in this case I was correct.
The 0.5m concentration hydrochloric acid was the slowest to finish the reaction.
The 2.5m concentration hydrochloric acid was the fastest to finish the reaction.
So this means that when the concentration of acid is strong the particles collide a lot and collide with a great force this help the reaction to happen quickly plus there is a catalyst present to speed it up even more. When the concentration of acid is weak the particles don’t collide as much and don’t collide with a great force so this is why the reaction is slower even if a catalyst is present.
When an acid has greater moles of concentration it just means that it is more concentrated within the contents. When an acid has fewer content particles we would call it more of a diluted acid.
During the reaction when the magnesium particles collided with the hydrochloric acid particles a gas was given off called hydrogen and the magnesium and hydrochloric acid reacted to form a solution called magnesium chloride. Here is the chemical and work equation:
Magnesium + Hydrochloric Acid Magnesium Chloride + Hydrogen
Mg 2HCI MgCl2 H2
Now I know that the 0.5m acid was the slowest to finish the reaction and the 2.5m acid was the fastest to finish the reaction when looking at my graph I noticed something very important. This thing was that when I looked at the 2.5m acid the line was very steep (had a high gradient) and the 0.5 acid had the least steep line (a lower gradient) so I came to the conclusion:
The steeper the gradient the faster the reaction
So from this vital piece of information I can work out that my graph is moderately accurate.
Evaluation
I think the syringe method was a good decision because as you can see the results in the table went as expected and the graph all made sense and nothing was really out of place apart from a few jumpy results but I missed out them results when it came to the graph.
So according to my graph the steeper the gradient of the higher the concentration the greater the rate of reaction. I was pleased how the experiments went and how the results came it also proved that my prediction was correct, I kept all of the magnesium and hydrochloric acid at the same mass so it will be a fair test.
A problem I encountered was when the experiment started was that nothing was happening the syringe was not moving, nothing happened for 120 seconds (experiment finish time) and in the end I found out that we had a stiff syringe so that was something I had to watch out for.
Resources
I mostly used a site called for some of my notes and info on rates of reaction
