This equation works out the concentration of the hydrochloric acid.
1M =1moler
My theory is that If I double concentration the rate doubles, 4moler is half the time of 2moler solution.
My theory is that the higher the concentration the more molecules that can react are able too because there is a higher percentage of them, so the quicker the reaction, this is also known as the collision theory.
Strategy
The purpose of our investigation is to find a link between what affects the amount of gas and the time it takes to reach that amount. We will be changing the percentage of concentration in the hydrochloric acid to see what affect this has on the time it takes to reach 100cm3 in the gas syringe.
Equipment
For method 1 we used: a rubber pipe, gas syringe, a holster (to keep the gas syringe in place) and a test tube. For method 2 we used: a gas collector, a rubber tube, a test tube, and a tray filled with water.
Preliminary test
We initially started with the experiment in diagram 1 because we worked out that there was a higher chance we would read the results correctly, the method in diagram 2 is a less accurate, because of the fact we would have to measure the amount of gas in the cylinder with a ruler and we could not find a tray deep enough to full it halfway with water. Diagram 1 was a more reliable approach besides from the fact it was quicker and easier to assemble, it was more accurate to measure as we did not have to use a ruler. We chose the rubber pipe as a glass or metal pipe would not bend or stretch to fit on the nozzle of the gas syringe. The gas syringe is a useful gas measuring device, because it can tell you how much gas is in there with one glance. The holster is to make sure the gas syringe does not fall over and leak the gas. The measurements of each reactant we will be using, as I have said before, are 2 gram of marble chips and 20cm3 of hydrochloric acid.
Method
I am going to describe the experiment procedure. Firstly clear a space for you too start assembling your equipment, find a pair of plastic gloves and goggles to be safe; then get a timer a test tube, and if needed a test tube rack. Get a holster; place the gas syringe in the holster so as to elevate above the test tube. Attach an air tight rubber tube to the gas syringe. Fill the test tube with 2 grams of marble chips; get 20cm3 of hydrochloric acid. Add the two reactants together in the test tube; quickly put the rubber tube on, so that it is air tight. As soon as you have put the rubber tube on the test tube, your partner should have started the timer and if not be waiting until an agreed measurement to set it off. Now you can measure where the gas syringe gets to every 5, 10, or 15 seconds until it reaches the end or another agreed measurement. Then repeat this experiment 2 – 3 times. Put your results into a table and work out the average of the results. If you were trying to do this more accurately increase the number of time you repeat the experiment. You can then change the measurements of the reactants and see what happens. Experiment one should look like this
For method 2 you need a reasonable amount of space, a test tube, with test tube rack (if needed), a tray filled with water, a gas collector, (carefully placed in the tray of water), a rubber tube, going from the gas collector out of the tray to the test tube. Fill the test tube with 2 grams of marble chips, and get a beaker of hydrochloric acid, 20cm3. Add both of the reactants to the test tube, and put the rubber tube on the top of the test tube so that it is air tight. It should look as shown below. I would measure how long it takes for the gas collector to fill up all the way. You can tell when this happens because the water starts to get lower inside the gas collector. Then repeat this experiment 2 – 3 times. Put your results into a table and work out the average of the results. If you were trying to do this more accurately increase the amount of time you repeat the experiment. You can then change the amount of reactants and see what happens.
Results
Here we used 2 Moler concentration; we got it straight out of the bottle, as was. We used small size marble chips though.
Preliminary tests
The outliers are marked in red
small chips
Concentration 100%
Average for small chip
Concentration 100%
Medium chips
We then used big chips to see if there was a difference in time.
We never got to 100cm3 because it would take too long.
Concentration 100%
Refined tests
Average for Medium chips
Concentration 100%
Small chips 75%
AVERAGE
Small chips 50%
AVERAGE
We will do no more than 50%; it becomes a waste of time after 50% and takes to long to measure. We did try 25% but it took along time for it to get beyond 10cm3 .
Observations
Preliminary results
This graph shows that the smaller the chips, the larger the surface area that faster they react with the hydrochloric acid around them.
I have noticed that when you increase the dilution of the acid the reaction time slows down because there is a smaller amount of reactants; therefore it takes longer for the reactants to reach each other and react.
In conclusion I have found the bigger the surface area, the faster the reaction happens, the more gas that is released. I can see this because of the gradient of the line. Also the higher amount of concentration the more molecules that can react with the marble chips.
This may be due to the “collision theory” where the hydrochloric acid molecules are hitting less marble chips because there is a smaller amount of hydrochloric acid and a bigger amount of water.
The procedure
If I were to do this again I would use the same equipment every time, and probably give myself more time to do the experiments, and do more of them, to a higher standard.
The reliability of the evidence
The reliability of the evidence is quite high because of the fact that we didn’t make it too complicated; we did have a very low range and not very many repeats. We used fairly simple recording methods. We used the acid from the same bottle so that it was always the same concentration unless we personally changed for the experiment. The fact that also there are only three outliers is a very low error rate, as I have done more than 30 readings.
The reliability of the conclusion
The conclusion is quite reliable because of the fact that we did do many experiments to make it fair, we firstly tried medium sized chips to see if they where appropriate to use, then we tested the big marble chips, these took a lot of time to record the results, and small chips reacted to fast to record the results, so we had no time to do it in. This is quite a reasonable method to test reactants.