Analyzing Reaction Rates: Acid Strength and Magnesium

The results should lie on straight lines. I will know from looking at the graphs, if I have any outliners. As you can tell from the straight lines. There are not any outliers and my results are correct. From this test I have decided that 2cm would be the best length to work with, as it provides a long enough time to record accurately the 2mole acid test, and it is also a reasonably short time for the 0. 5 mole acid.

The reaction is as follows:

Magnesium + Hydrochloric acid --> magnesium chloride + hydrogen Mg + 2HCL --> Mgcl2 + H2 Metal + acid --> salt + Hydrogen.

The magnesium displaces the hydrogen atoms from the chorine to give magnesium chloride salt solution and hydrogen gas. This happens because magnesium is more reactive than hydrogen. I am using a gas syringe to measure the amount of hydrogen produced as I can then work out the rate of reaction, and give more accurate results. I will then repeat the experiment using and 2.

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5 mole acid. I will make this a fair test by  Ensuring that only the acid strength changes if  The size of the magnesium changes  The area of the magnesium changes.  The size of the test tube changes.

The ease of movement by the gas syringe changes It will affect the experiment. As always when working with high strength acid you should always wear goggles. I will repeat each acid strength 3 times and average the results to hinder an anomalous result. Results Acid Strength (mole) Time (s) T1(ml3) T2(ml3) T3(ml3) Average(ml3) It is difficult to see any trend using only a table so I have produced a graph that held all the data:

As you can see from the graph, the time at which the reaction stopped is more or less the same ml3.

This is because I used the same amount of magnesium, and the same amount of acid, so I will get the same amount of hydrogen, no matter how strong the acid is. You can also see from the graph the speed at which the reactions took place. 0. 5 moles being the slowest and 2. 5 being the quickest. This proves my prediction that the stronger the acid, the quicker the reaction The collision theory explains how a reaction can only take place when reactive particles meet, under certain conditions.

It stands to reason that if you have more reactive acid particles (a higher concentration of particles) in the same place, they are more likely to collide with another particle, and react. However, other aspects also affect the reaction, but are all made more likely if there are more molecules. For the molecules to react they have to have  Enough energy to achieve an activated complex. This energy that they need is activation energy.  The right orientation for the reaction to take place. Also, when these reactions take place quickly, they produce a lot of heat, the where quickened in the stronger acids, because of the increase in heat.

This increase in energy makes the particles vibrate quicker, and therefore collide with other particles, again increasing there chance of reaction. This is why 2. 5 mole acid had the quickest rate of reaction. I then need to prove my prediction that the rate of reaction would double when the strength double, so I calculated how much gas per second was given off by calculating, a rate of reaction, using the formula. Rate of reaction = Time taken stop reacting Gas given off Acid Strength (mole) Rate of Reaction (Time/gas)  1Again to illustrate my results I put these results into a graph.

I would hope for a completely straight line because when you double the acid strength, the rate of reaction should double. As you can see from the graph and results table my prediction was correct until it came to the 0. 5 mole acid. These are the results rounded to show my prediction. Note that the 0. 5 mole acid is missed out Acid Strength (mole) Rate of Reaction (Time/gas) Calculation I have several theories of why the 0.5 mole acid did not react as expected.