Introduction: In this experiment, I am going to find out what happens when different concentrations of hydrochloric acid are mixed with the same amounts of magnesium. The probable outcome of this is that the reaction will be more vigorous to start with, meaning the reaction would end up being completed faster, if the concentration was to be higher than normal. This would happen because there would be more atoms of hydrogen and chlorine in a higher concentrated solution, to react with the magnesium.
As you can see, the circles that represent the hydrogen and chlorine atoms of the hydrochloric acid find it a lot harder to fit inside the right-hand rectangle, that is the same area as the left rectangle (the rectangles representing the solution of acid). This means that the right-hand rectangle is more concentrated, as the hydrogen and chlorine atoms take up more space. If a piece of magnesium were to be placed in the rectangles, then the more vigorous (and faster) reaction would take place in the right-hand rectangle.
This is because the magnesium would be confined to the (smaller) area where there aren’t hydrogen or chlorine atoms, so the collision rate is likely to be higher. Prediction: I predict that the higher the concentration of HCl, the faster the reaction will take place. As I said in the introduction, the atoms will find it easier to react (collide) with the magnesium, as there would be more atoms to react with it. I think that the graph I will draw from these results will show proportionalities between the concentrations of the acid, and the time taken to react.
However, the table wont show proportionalities, because it won’t take into account the different differences between each concentration. For example, 0. 1M, 0. 2M, and 0. 5M (which are some of the concentrations I will use) don’t have the same difference between each other. My graph will take the different differences into account, as you will see later. Method: This is the equipment I will use in the experiment 6 x 3cm magnesium strips. 6 x 10ml of hydrochloric acid – each having a concentration of 0. 1M, 0. 2M, 0. 5M, 1M, 2M or 4M. 10ml measuring cylinder to measure amounts of acid used.
6 test tubes. Test tube rack. Stopwatch. Ruler to measure size of strips. Scissors to cut strips. Sticky labels to label each test tube. I am going to make this a fair test, so that each amount won’t turn out different than it should do, because for example, less magnesium wouldn’t take longer to react with the HCl. I am going to use the same amount of acid (10mls) and the same amount of magnesium (3cm strips) to achieve this. I will do this by measuring precise amounts of acids with a measuring cylinder, and a ruler to measure the strips.
In fact, the only thing that I want to be different for each reaction is the concentration of the acid (with all six being between different concentrations between 0. 1M and 4M, as I mentioned in the list above). I am going to fill the 6 test tubes with the 10mls of hydrochloric acid, which will be measured with the measuring cylinder. I will then drop the magnesium strips into them. I will time the reactions for however long it will take the magnesium to disappear (i. e. when the reaction has finished).
I am also going to do more than one test, to make sure that I don’t do any of the tests wrong. If I were to only do one test, then any anomalous results will look more inaccurate, than they would do if I were to do two tests. This is because if one test had been done wrong and I didn’t know about it, and the other test had been done correctly, then the average result would reduce the deficit of the anomalous test by half. The only problem with this would be if I did all my tests wrong – because then my averages wouldn’t make a difference on the deficit of the results.
I will try to do two tests, in the two lessons allocated for the practical side of the experiment. In each lesson, I will run three reactions at once, twice. I will do this by running the 0. 1M, 0. 2M and 0. 5M reactions first, and then once those have stopped reacting, I will set up the 1M, 2M and 4M reactions up. If my prediction is correct, then this would be the way to do it to be less time-consuming, as not a lot of time would be spent on the reactions involving the 0. 1M, 0. 2M and 0. 5M acid. The only problem I see with this method is the time factor.