whether the strength of Hydrochloric acid will affect the speed of the rate of reaction when reacting with Magnesium Ribbon.

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I want to find out whether the strength of Hydrochloric acid will affect the speed of the rate of reaction when reacting with Magnesium Ribbon.

Variables

There are two important independent variables in my investigation the first of which is the concentration of the Hydrochloric Acid used during the investigation. The concentration of the acid will partly determine how fast the reaction takes place, if we put some of the magnesium ribbon into the HCL at 2molar then it might have simply dissolved within a few seconds and then I would not have had time to record down any decent enough results to plot a graph with. The other important independent variable that will affect the speed of the rate of reaction is the length of magnesium ribbon. We need to put enough Mg Ribbon into the HCL so that it doesn’t run out straight away but also so that the experiment stops by itself once the gas syringe has filled up.

The reasons for choosing these two independent variables are that it would be too hard to try and find a catalyst for this experiment; a catalyst is a substance that increases the rate of a chemical reaction without being consumed in the reaction. Finding a catalyst for this particular experiment could take months never mind the amount of time we have been given for our experiment.

The independent variable that I will change is going to be the hydrochloric acid, we will use 50ml of HCL at the following molarity concentrations; 2molar, 1.6molar, 1.2molar, 0.8 molar and 0.4 molar. I have decided to experiment with these different strengths of molar because I think it will give a wide set of results to put into a graph.

The dependant variable I shall be measuring will be the time it takes for the magnesium to completely react with the hydrochloric acid, I shall record the times for each concentration of hydrochloric acid three times so that it makes it a fair test.

To ensure the investigation is fair we will use the same length of magnesium ribbon for all the different strengths of hydrochloric acid and the length will be the one that we picked out from the preliminary experiments. Another way in which we will keep the investigation fair will be to carry out an experiment at each concentration of hydrochloric acid three times so that we can then get hopefully around the same outcome from each experiment, and if there are any anomalies we can try to explain why they happened.

The final way in which we will try to keep our experiment fair will be to use the same gas syringe each time therefore we will not have one which glides smoothly for one experiment and one that sticks and jumps for a different experiment. Although we cannot always guarantee that the experiments will be fair because we will not always get the same bottle of hydrochloric acid because there will not be enough to carry out all the experiments with just the one bottle so the different bottles could be at ever so slightly higher or lower concentrations of hydrochloric acid which will affect the  outcome never the less.

Prediction

I think that my results will show that the hydrochloric acid with a molarity of 2 will finish reacting the quickest because it is the strongest hydrochloric acid and I predict that the slowest experiment to finish reacting will be the 0.4 molar strength of hydrochloric acid. I think that the results will go slower and slower the nearer they are to the 0.4 strength of hydrochloric acid. The reason that the experiment with hydrochloric acid at 2 molar will dissolve the magnesium ribbon faster is because it is of a stronger concentration and so the molecules in the hydrochloric acid move faster and so react with the magnesium ribbon quicker.

Preliminary Experimental Work

I have carried out two preliminary experiments, the first reason that I carried out these were to see which of the two would be easiest and most accurate to carry out in the actual experiment. Then once I had picked one of the two to take forward I then went on to try to get some good measurements and molar strengths to use in the actual experiment.

Burette Method

Equipment

Conical Flask, Bung, Connecting Pipe, Burette, Large Measuring Jug.

For this method we first set up the equipment needed to carry out the burette experiment as shown below;

 

The burette method consists of the Magnesium ribbon being put into a conical flask with 50ml of hydrochloric acid quickly put the bung in once the magnesium ribbon has been put in, then the gas will go up and around the pipes and go into the burette which will be filled with water as air bubbles. This method was hard to take down results because every time a bubble of the gas released went through the burette it would simply stop and start, for example just as I was abut to take a reading a bubble shifted the reading down 7ml and so this gives the results a certain degree of inaccuracy. We took down measurements in 5 second intervals. The burette has a volume of 50ml³.

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Gas Syringe Method

Equipment

Conical Flask, Bung, Connecting Pipe, Gas Syringe, Hydrochloric Acid, Magnesium Ribbon, Clamp, Stand.

For this method we set up the equipment as follows;

        

The first to do is to gather together all equipment, then once that is done get the conical flask and put the bung into the top of it. Then connect the pipe from the bung to the gas syringe, making sure that it is air tight. Then once everything is set up get the stop clock ready, measure out the 50ml of hydrochloric acid and pour it into ...

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