I measured the sulphuric acid in a measuring cylinder for the most accurate reading then poured it into a conical flask and took the temperature using a thermometer and decided whether to increase or decrease the temperature. To increase the temperature I heated a beaker of water then placed the sulphuric acid in the conical flask to heat it. I found this was a safer way than to heat the acid directly on a bunsen burner. Once the temperature was correct I added the magnesium ribbon and immediately place the rubber bung on the flask, this was connected to a gas syringe. The gas syringe is the best equipment to measure gas, as it is very accurate. I started the clock and after 15 seconds I recorded the results into the table. All the equipment I chose worked well and was very accurate, in the final experiment I am going to heat up the water on the bunsen burner as the kettle was very slow and not hot enough.
I learnt from my preliminary work I need to do 2 readings for each temperature to get an average. I need to change the acid each time. I will also record the results over 30 seconds, reading off the gas every 10 seconds as this will give me a wider range of results and I found that 15 seconds was very short and wont give me a curved graph and I will not be able to see how much the increase of gas is. I am going to range my temperatures from 10°C to 70°C, going up each time in 10°C. I chose this range as it is safe and there will be enough results to have a fair experiment. From the results table I found it is also possible to find the averages by adding together the two results from the same temperature and dividing them by two. These are shown in the graph.
Prediction
I predict the more you heat the sulphuric acid and the hotter it is the quicker the rate of reaction and the more gas given off. I think this because at a higher temperature on average the particles move faster. These faster moving particles will collide with each other with increased energy. The collisions are more successful than at a lower temperature. The faster moving particles react and give off gas: the hotter the acid, the faster the particles therefore move will be reaching the level of aviation energy and colliding and reacting.
Safety
To make sure any experiment is safe I will wear goggles to protect my eyes at all times and an apron. I will wash my hands if I get acid on them. I have a string attached to the gas syringe so the end cannot fall out. I am going to have the gas syringe on a clamp so it cannot fall onto the floor. I will use a safety mat to prevent anything burning. I will clear the desk free of objects and tie my hair back.
Method
- Collect the following equipment:
- Conical flask,
- Bunsen burner,
- Safety mat,
- Measuring cylinder,
- Gas syringe,
- Thermometer,
- Clamp,
- Boss,
- Stand,
- Stop watch,
- 1 molar Sulphuric acid,
- Magnesium ribbon
- Ice
- Set up the bunsen burner, and place a beaker ¾ full of water on the heat.
- If you need to decrease the temperature of the water, get a beaker of crushed ice.
- Set up equipment like so:
- Measure out 75ml sulphuric acid in the measuring cylinder,
- Pour into a conical flask.
- Place gas syringe horizontally onto the stand, held on by the boss and clamp.
- Check the temperature of the water and get it a few degrees above or below your target temperature for the sulphuric acid.
- Place the conical flask containing the Sulphuric acid, in the beaker of either ice to cool or heated water to heat and wait for it to reach target temperature check with a thermometer.
- Take the conical flask out of the beaker once it is at the correct temperature and place 1 magnesium ribbon (8cm) in the conical flask with the acid.
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Immediately place the rubber bung on the top and start the stopwatch.
- Read off the gas cylinder every 10, 20 and 30 seconds.
- Change the Sulphuric acid each time, measuring it in the measuring cylinder each time for accuracy.
- Repeat twice for each temperature.
Diagram
Results
These are the averages I have worked out from my results table. To find out the average I added the 3 results at
Conclusion
From the graphs and the results table I can see that heating acid does make a difference to the amount of gas produced. The higher the temperature of the sulphuric acid, the more acid is produced. I can also see that the higher the temperature, the quicker the gas is produced. In the higher temperatures the gas was being produced a lot quicker than the lower temperatures. At 10°C only 33ml of gas was produced after 10seconds, at 70°C, 75ml of gas was produced after 10seconds, showing an increase of 37ml, this is a large increase. Each time the temperature was increased by 10°C the gas produced increased from 4ml-8ml, based on the averages. The rate of the reaction increased because of the rise in temperature. The rise in temperature caused the particles to move faster, these faster moving reactants will collide with each other with more energy than they would do at lower temperatures. When they collided in the experiment the gas was given off therefore the faster the particles moved, the more particles collided, giving off more gas.
The results table proves my prediction, where I said that more gas would be produced at a higher temperature. Also my reason for predicting was correct when I said about the particles moving faster.
Evaluation
I think my experiment worked very well and the results prove this. The results are good and show a pattern and support my prediction. I think the results are reliable and set out a clear answer for my investigation. None of my results were abnormal or seemed out of place.
The equipment I used I felt was the best I could use and the most accurate. It really helped me doing a preliminary experiment, as I was able to see how I could improve things. I did improve a lot of aspects of my experiment, such as the range of time and this meant I did have better results. I could have improved my experiment further by using an even larger range of temperatures and time. I could have started on 0°C and gone up to a higher temperature. This would have given me larger data, which would be better.
I could also carry on my experiment, to carry out further investigations by changing some of the key variables. I could change the strength of the acid to 0.5 molar or a stronger. I could also see if changing the length of the magnesium ribbon would make any significant changes to my results. I could add a catalyst to speed up the reaction and see if it would make as bigger difference as changing the temperature did. I could have also changed the volume of Sulphuric acid.
I am pleased with how this investigation went and also the results it proved. I don’t think there are many things I would do differently except the ones I have written about.
Anna Boast 10L Mr Williams
