I will take into consideration that the speed with which I put in the marble chips, place in the bung and press the stop watch may well affect how well the experiment works. Although these factors will affect the end result so long as they are kept constant throughout then it should not matter too much.
I also did a trial experiment beforehand to give an idea as to what to do in our investigation because it allowed me to know what amount and size of marble chips to use in the proper experiment. It was also a very good thing to do because it showed me how to use the equipment properly and safely and gave an idea as to what was to come.
Apparatus
- Conical flask with bung
- Delivery tube
- 2 Measuring Cylinders
- Beaker
- Tub of water
- Weighing scale
- Stopwatch
- Hydrochloric Acid Solution
- Medium sized Marble chips
Diagram
Method
After collecting the apparatus and arranging as shown above, fill the tub full of water and measure out 40ml of 0.5M acid and pour it into conical flask.
Weigh out 10 grams of the marble chips; use the same weight each time for each of the molarities. Place the chips into the conical flask and insert the bung.
As the reaction takes place bubbles should start to come out of the delivery tube into the upturned measuring cylinder. From the first bubble measure how long it takes for the upturned measuring tube to fill up with gas.
Record the result and refill the upturned measuring cylinder with water, wash out the conical flask and weigh out the next lot of marble chips.
Repeat the experiment but each time using a different concentration of acid 0.5M more each time until you get to 2M and as you will need 5 different concentrations you can do 1.25M or 1.75M acid aswell. You may want to repeat the experiment three times to get a more accurate average for each concentration.
Fair Test – Controlling the Variables
- What I will keep the same –
Each time I repeat the experiment I will keep the temperature, surface area of the marble chips, amount of acid used and the amount of carbon dioxide to be collected the same. These are the other factors, which may affect the rate of reaction.
The only thing that I will change each time is the molarity of the acid. Each time I will increase the molarity by 0.5M (apart from the fifth concentration), there is little problems with using the conical flask over because I am starting from the weaker to the stronger concentration of acid in turn.
Results table
Conclusion
My results prove my hypothesis. The higher the concentration of acid, the faster the rate of the reaction. The results also showed a valid pattern, as the concentration doubled so does the rate of reaction. Between 0.5M and 1.0M the amount of time roughly halves as the concentration is doubled, this is also true for the 1M and 2M gap. If my results had been more accurate I think the results would show the concentration of the acid and the rate of reaction to be proportional.
The graph also supports my prediction. On the graph, the steeper the curve, the faster the rate of reaction.
Evaluation
Overall I am pleased with my results and the way the experiment was carried out. I think my results were fairly accurate and proved my hypothesis. To make the overall experiment results more accurate we repeated it three times and then took the average.
If I were to do this experiment again I would probably make it more accurate by using smaller particles of marble chip so I could match up surface area and weight more accurately each time. I would like to then see if the concentration of acid is proportional to the rate of the reaction.
Some other areas in the experiment that I feel I could have improved on were factors like, controlling the stopwatch. There is a lot of human error here. But the inaccuracies due to them were minor because I paid close attention to these during the experiment.
Bibliography
- to create the graph.
- to do research about rates of reaction.
By Abbas Hooda 11LJG