Magnesium + sulphuric acid ==> magnesium sulphate + hydrogen
Mg(s) + H2SO4 (aq) ==> MgSO4 (aq) + H2 (aq)
Magnesium will react with hydrochloric acid because it is higher in the reactivity series than hydrogen. When the two chemicals react a displacement reaction will take place and the magnesium will displace the hydrogen in the hydrochloric acid forming magnesium chloride and hydrogen gas.
Prediction:
I predict that as the temperature increases due to the reaction, the reaction will increase further, because at a higher temperature molecules move around faster as they have more energy, therefore increasing the likelihood of a collision. I also predict that the higher the concentration of acid, the quicker the magnesium will react and dissolve, as in more concentrated acid there are more particles, also increasing likelihood of a collision.
Apparatus:
- Test Tube Rack
- Strips of Magnesium Ribbon
- Bottle of Sulphuric Acid
- Bottle of Water
- Stop Clock
- Test Tubes
- Safety Goggles
- Measuring Cylinder
Method:
- We first collected all apparatus listed above.
- Put on our safety goggles at the beginning of the experiment
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We started with 1 test tube with 30cm 3 of Sulphuric Acid in it. We added a strip of magnesium ribbon and began timing the reaction
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For the second test tube we measured 25cm 3 of acid and 5cm 3 of water and added them together, we then again added a magnesium ribbon and timed the reaction.
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We repeated this a further four times, each time taking away 5cm3 more of acid and adding 5cm 3 more of water.
I have chosen to repeat the experiment three times therefore allowing me to calculate an average. This will ensure higher accuracy for my results.
Diagram:
Variables:
- Acid Concentration
- Amount of water added
- Temperature within the test tube
Constants:
- Total volume of acid and water when mixed together
- Length of Magnesium Ribbon
- Room Temperature
Factors that could affect my Experiment:
- Concentration of acid
- Type of acid used
- Surface area of the magnesium
- Temperature of the acid/water
Fair Test:
To ensure my experiment is a fair test the following factors could be kept the same -
- Length and surface area of magnesium
- Volume of total acid and water when added together
- Starting Temperature of acid/water / Room temperature
I will also repeat the investigation three times per different concentration of acid.
Safety Measures:
- Ensure you wear safety goggles at all times
- Tie long hair back
- Take care whilst handling glass test tubes
What I saw:
As the reaction took place the magnesium turned white and then fizzed, to finally dissolve. The acid/water fizzed up and turned cloudy, and then settled down and went clear again after a few minutes.
Conclusion:
My results tell me that the test tube with the most amount of concentrated acid used was the quickest to react to the magnesium ribbon. This is because as it being the highest concentration of acid it contained the most acidic particles and as a by-product of the reaction the temperature increased. Energy built up causing particles to move around quickly, therefore colliding with atoms quickly, causing a fast reaction. This I stated in my earlier prediction.
Altogether I tested 6 different concentrations of acid. The quickest to react was 30cm3 which was the most concentrated acid I used. The slowest to react was a combination of 5cm3 acid and 25cm3 water which took 15 minutes to complete the reaction with the magnesium ribbon.
Evaluation:
Overall I think I have made my investigation a fair test. To my best ability, I tried to accurately measure each measurement of hydrochloric acid and water. I also accurately measured the time the reaction took to the nearest second on a stop clock. The results collected were reliable as I repeated each concentration three times.
