Acid Chloride
One molar strength hydrochloric acid has half of the amount of atoms than two molar strength hydrochloric acid has; therefore collisions of the particles occur twice as often.
Another factor which is included in collision theory is that of heat. If the chemical is heated then the particles move faster, thus making the collisions more frequent. For this reason the investigation must all be conducted at the same room temperature.
Prediction
I predict that as the strength of the hydrochloric acid increases, as does the rate of reaction. The reason I am making this prediction is based upon my past knowledge, and preliminary tests, but mainly on my knowledge of collision theory. The higher the strength of the acid, the more particles there are for the magnesium particles to collide with, so a quicker and more vigorous reaction will occur, and hydrogen will be produced at a higher rate.
Apparatus
4cm Magnesium ribbon strips x15
Hydrochloric Acid- in ½ M, 1M, 2M, 3M and 4M strengths
100cm³ measuring cylinder
25cm³ measuring cylinder
250cm³ conical flask
Rubber bung and delivery tube
Water bath
Stopwatch
Safety goggles
Method
The bowl is filled half full with water, and the 100cm³ measuring cylinder is filled with water and turned upside down, forming a vacuum. The end of the delivery tube is under the water beneath the measuring cylinder, so that when the hydrogen is produced it is collected in the measuring cylinder.
25cm³ of the chosen molar strength acid is then placed into the conical flask. The strip of magnesium is dropped into the acid, and the rubber bung replaced as quickly as possible. As soon as this is complete then the stopwatch is initiated, and is stopped when the amount of gas released reached 55cm³.
Results
Time Taken to Reach 55cm³ of Hydrogen Produced
Rates of Reaction
The rate of reaction is worked out to show how much hydrogen is released per second. The rate of reaction is defined as a measurement of the change that happens in a single unit of time- In this case seconds because it is the easiest unit to analyze.
Conclusion
From conducting the experiment, I have discovered that my prediction was accurate in its qualitative form. There is no obvious numerical link between the different molars, apart from the fact that as the molar increases, the rate of reaction doesn’t increase proportionally; for example, the rate of reaction increases dramatically as the molar doubles.
Evaluation
In my opinion the investigation was a success and was carried out accurately. However, there are some factors which could be improved to make for a more accurate result for possible future investigations.
One such factor is that of using the magnesium ribbon. Using 4cm strips is not very accurate, and could be improved by measuring out a specific mass.
Also, using a lower molar variety of acid would have meant for a slower reaction, thus less hydrogen would escape due to human error.
After completing the experiment, I feel that all the experiments were conducted to a suitable degree of accuracy, and I am satisfied with the results that I have received.
