Analysing
The concentration of the acid affects the rate of reaction.
Fair Test
Use the same volume of acid for each test. Use the same mass of magnesium for each test also because if the lengths of the Magnesium are different, then the surface area and the mass of Magnesium will be affected. This will produce more than one variable, which will make the results less accurate. Keep the temperature of acid the same. Start the timer as soon as the acid is poured onto the magnesium. The beaker must be washed out after each experiment because if it is not then there will be still reactants in the beaker like the Hydrochloric acid.
Method
- Put on the safety goggles.
- Collect the equipment.
- Cut the magnesium strip in half and weigh each piece. Ensure all the pieces of magnesium are the same length, (0.05g)
- Put the 10cm of acid in the measuring cylinder.
- Place the magnesium strip in a small beaker.
- Pour in the hydrochloric acid into the beaker and start the timer as soon as the acid is poured in.
- Stop the timer as soon as the Hydrochloric acid and Magnesium stops reacting. The Magnesium will have stopped reacting when there is no fizzing.
- Repeat the test again three times for each concentration of acid, 0.5, 1.0,. 2.0M, 2.5M and 3.0M.
There was an Anomalous results in the second experiment so they will be discarded (the 0.75’s set) when working out the averages.
Then using the Formulae a = n+n,
2
the table of averages will be made.
Conclusion:
From the graph and my results table i can see that my prediction was proved right .This is due to the fact that i stated that the highest concentration Hydrochloric Acid (1.5M) would have the fastest reaction rate(4.5 cm3 produced in 10 s) whereas the lowest concentration of Hydrochloric Acid (0.5M) would have the slowest reaction rate (1 cm3 produced in 60 s)which were both shown to be correct. However this is not including water which didn’t have any effect on the magnesium whatsoever.This is because in order for any reaction to occur, particles of both substances must first collide.
In a solution with a higher concentration there is a larger amount of particles to react thus allowing for more successful collisions and a higher collision frequency to occur. As reactions rely on successful collisions occuring, a higher collision frequency leads to a faster reaction rate. Furthermore as the number of water particles decreases there is becomes a smaller chance of the acid particles becoming obstructed by the water particles thus giving them more possibilities to collide with the magnesium.
Evaluation
I think my results could have been more accurate as I may have forgotten to rinse out the beaker cylinder between testing different concentrations. Another reason may have been that my measuring wasn’t accurate enough. I may have used too much or too little acid concentration into the cylinder. The experiment could have been repeated using a wider range surface of areas. It could also be repeated using a different metal, other than Magnesium to make sure that the conclusion does not only refer to Magnesium. If the acid used was changed, the conclusion would not just apply to Hydrochloric acid. I would also use a gas syringe to measure the volume of gas.
