Aim
I plan to investigate the effect of concentration of acid, in the reaction between dilute hydrochloric acid and magnesium ribbon. The rate of a chemical reaction is a measure of how fast the reaction takes place. It is important to know that a rapid reaction is completed in a short period of time. Some reactions are very fast, for example; the formation of silver chloride precipitates when silver nitrate and hydrochloric acid solutions are mixed. In this investigation I will test different concentrations of acid reacting with magnesium.
Apparatus
Hydrochloric acid
Water bath
Measuring cylinder
Magnesium (4cm)
Stop clock
Water
Method
- I got a tube and filled it to the top with water and placed it up-side down in the water bath which also contained water. I made sure that no water could escape from the measuring cylinder.
- I then got a piece of magnesium which was 4cm long and 25ml of hydrochloric acid and put it in a beaker.
- Then, ready with the stopwatch, I quickly dropped the magnesium ribbon into the acid, and started the stopwatch. This was all done in a very short space of time to make it a fair test and to get accurate results.
- I then recorded the results in a table. I then repeated the experiment for the rest of the concentrations. I then repeated the whole experiment again and recorded the average for both results and the concentration.
Prediction
I predict that the more concentrated the acid the quicker the reaction will take place, because the more concentrated the acid is then it will make the magnesium react faster and more hydrogen will be given off in a quicker time.
Diagram
Results
Graph
Analysis
From my results I can conclude that the stronger the concentration, then the quicker the reaction happens. This matches my prediction because I predicted that the concentrated the acid was, the faster the reaction will happen. This is shown in my graph. The shorter the line, the less time it took. So the shortest line is the strongest concentration and the longest line is the weakest concentration.
Evaluation
I think the main error in my experiment was that I could not put the magnesium in at the same time as setting off the stop watch. This is why I worked in a pair so one of us could put the magnesium in and the other could set the timer off. Even though we did this as carefully as possible, we still could not be sure of its accuracy. If we used some kind of machine that could start the stopwatch as soon as the magnesium was put in then it would be better but we did not have the equipment.
To further my experiment I could get a bigger measuring cylinder which will carry more water. With this I could check that my results were correct and find out more detail about it. I could also try stirring the solution to see how that affects it. It would probably speed up the reaction because the molecules are moving faster. The only problem with this is I would not be able to be sure that I was stirring it at the same speed constantly so that could affect the results. If I could be sure I was stirring at a constant speed then my experiment could be extended and I would have more information.
