In this particular experiment, my altering factor will be the length of the magnesium strip; this will be measured in cm.
Diagram:
Plan:
Equipment:
- 100ml measuring cylinder
- Conical flask
- 30cm magnesium ribbon
-
100cm3 dilute sulphuric acid
- Plastic tub
Method:
I will take my 30cm magnesium strip and divide it up into different lengths starting with 1cm, 2cm, 3cm, and 4cm. I will repeat this twice more using all of each length. One piece of each length was used in the preliminary investigation and the other two pieces of each length in the main experiment.
After setting up the equipment as shown in the diagram, I will pour 10 ml of the sulphuric acid into the side arm flask and then add the piece of magnesium to the acid in the side arm flask and put the bung on the side arm flask. It will be carried out in this order as it was found to be the most efficient in the preliminary work. I will then collect the hydrogen gas in the measuring cylinder.
To make sure it is a fair test I will keep certain factors constant. The factors I will keep constant are the same amount of acid (in ml), volume of acid, type of acid and concentration of acid. Also I will wash all equipment to stop contamination and I will not shake the flask because I cannot ensure that I will shake the flask the same way and amount each time, which will influence the results.
I will make it a safe experiment by wearing safety goggles at all times, dispose of all chemicals, clear up any spillages and by handling all glass equipment and care.
Results:
Conclusion:
I can see from the results I obtained from the experiment, that my prediction was correct. As the length of the magnesium increased, the volume of hydrogen gas produced increased. This also proved as the surface area of the magnesium increased so did the volume of hydrogen gas produced.
This is to do with the collision theory when we increase the surface area of the magnesium it has a higher probability of colliding with an acid particle which will create a chemical reaction which produces a by-product of hydrogen gas, thus the more collisions the more gas.
You can see from my graph that no anomalous results were taken which shows that my results were fairly accurate because I carried out the experiment to the guidelines laid out in my plan to ensure a safe and fair test.
Evaluation:
My experiment was not as accurate as it could have been which slightly lowers the reliability of my results. To make my experiment more accurate I could find a more accurate way of cutting the magnesium into strips or using the weight of magnesium instead of length. Also I could develop a way of releasing the magnesium into the acid without losing any gas from the flask. Also I could of changed the collecting method and used a gas cylinder which would be more accurate.
A way I could further this experiment is by changing the other variables, such as the type of acid, the strength of acid or the volume of acid.