Preliminary work
We only used magnesium ribbon in sizes 20mm and 10mm, in 20ml of acid and 10ml of water. Using the stopwatch to time the reaction we found that: The 20mm piece of magnesium took 40.16 seconds to fully react in the acid, and the 10mm piece of magnesium took 35.84 seconds to dissolve in the acid. In out main experiment we are going to choose a 15mm piece of magnesium with acid. The experiment will be repeated three times to make sure our results are accurate. We have also done 20mm and 10mm of magnesium in 10ml of acid with 20ml of water. 20mm: 1.26 minutes and 10mm: Experiment done wrong. We used different sizes of magnesium to get a range of results.
Equipment (main experiment)
This is the equipment we are going to use in our main experiment. We will be using hydrochloric acid with magnesium ribbon. We will measure the magnesium using a ruler then cut it, using scissors this will not be 100% accurate but it is near enough. We will measure the water and acid using a pipette, measuring cylinder and a beaker with both the solutions it should add up to 30ml. The measuring cylinder is more accurate for measuring liquids than the beaker. We will measure how long the reaction takes by using a stop-clock. We will ensure we take standard safety precautions whist doing the experiment, by making sure goggles are worn at all times, and we tip away the acid, once we have done the experiment.
Here is the Equipment list:
- Magnesium
- Hydrochloric acid
- Water
- Beaker
- Pipette
- Stop-clock
- Scissors
- Measuring cylinder
- Goggles
Prediction
I think the experiment could go similar to our preliminary work, if we are using 15mm of magnesium with different concentrations of acid. The results will be all around the same (using the same concentrations and amount of magnesium). But as I increase the concentration the reaction time should be decreasing. If we use 20ml of acid and 10ml of water we are not getting full concentration of acid this will affect the rate of reaction because the magnesium will not be reacted as fast as it is been hit with water particles which have no affect unlike the hydrochloric particles, which will attack the magnesium and react in it. When you want a stronger concentration of acid, then you must add more acid, so you are adding more acid particles in with the current particles of water and acid. Which means there is a lot more acid particles than the water particles, this means that the magnesium will react faster because there is more acid particles. So this means more successful collisions are likely to take place, between the magnesium and acid particles. To make a concentration weaker, you add more water, this means there is a lot more water particles than the acid particles, so the reaction of the magnesium will take longer.
Method
In my main experiment I will use 15mm of magnesium with my 20ml of acid and 10ml of water. I am going to be using a stop-watch to see how long it takes the magnesium to dissolve. This experiment will be repeated three times to make sure my results are accurate
Results
Analysis
We have found that the stronger the concentration of acid, the faster the magnesium will react, if u have all acid 0ml of water, then there are no water particles to prevent the collisions been unsuccessful. So the acid particles will quickly collide with the magnesium and react it away. If we used a powder instead of the ribbon, the reaction would be over in less than a few seconds, because there is a bigger surface area of the magnesium which will make it react faster, due to the collision theory. Looking at the results table, we are able to plot a graph from our results. Our graph shows us that the different concentrations of acid generally follow the same trend. (circled)
The graph shows the average time taken, for magnesium to react in hydrochloric acid, there are anomalous results, I am pleased with the results.
Evaluation
The experiment we did (what affects the rate of reaction between a metal and an acid) was quite successful we got a good set of results and we did the experiment as efficiently as possible. We made sure that is was a fair test all the way through. We had 1 anomalous result. This good be from a number of things, like us making mistakes with the preparation, or the readings. They results are plotted because of the fact that the magnesium will have had a large surface area that is exposed to acid and water particles which will be colliding with the magnesium surface causing a reaction( only the acid particles will react, the water particles will just bounce off, it would be unsuccessful) This anomaly appears to be well out of the line of best fit, I think we made a mistake with the readings, we took of the reactions we did. As this experiment was done in a group, it could have been 1 of work mates, who slipped up and made a mistake but it is my responsibility, to make sure that I get my results done accurately. We could have improved our coursework by making sure we did the experiments on time. And worked at a reasonable speed instead of chatting too much and lagging behind the rest of the class. To back up our theory we could do the experiment which we prove our results and theory. We tried to make sure that our magnesium ribbon was the same size all the way through. It could have been easier if it was a powder then we could have weighed it to get a precise amount. It was quite a good experiment we are learning new things.
By Lewis Jones 10AP