Investigate the factors that effect the rate of the reactions between magnesium and acid.

Fair Test:

 I will make this experiment fair by controlling the different factors. This reaction is exothermic so during each experiment I will place the equipment in cold water so that no extra heat is added because higher temperature increases the rate of the reaction and therefore would ruin my results. I would also make sure I use the same amount of hydrochloric acid by measuring it in a conical flask. I will also make sure that the size of the magnesium strip is the same each time by using a ruler to measure it.

Preliminary Experiments and results:

 In my preliminary experiments I chose which size of magnesium I shall use for this experiment. I found that 2cm of magnesium strip was the best measurement to use as it showed in the experiments because all other measurements seemed to have either not fizzed enough or fizzed too much.

I also found that the magnesium strip reacted straight away with the hydrochloric acid when I dropped it in. This means that I will start the stop clock as soon as I drop the magnesium in. I will also start the concentration from 1.0 molar because anything below would not show much of a result. In the preliminary experiments I noticed that as the concentration is increased the rate of the reaction will also increase. I expect the same thing to happen in this experiment.

Apparatus

• Strip of magnesium
• 20cm³ of Hydrochloric acid
• conical flask
• trough
• measuring cylinder
• delivery tube
• ruler
• stopclock

Method:

1. First of all I will collect all equipment and measure how concentrated the hydrochloric acid should be by first using 1.0 molars.

2. Then I shall put the Hydrochloric acid in the conical flask

3. I then will fill a trough with water and put the conical flask into it and then fill another trough with water and fill the measuring cylinder with water to the top and quickly put it into the water

4. Then I will put the delivery tube underneath the measuring cylinder

5. I will add the magnesium to the hydrochloric acid and straight away start the stop clock

6. I will do this experiment a number of times increasing the concentration of the hydrochloric acid by 0.2 molar.

Safety:  To ensure that the experiment will be safe I will wear goggles at all times when handling the experiment and be careful not to spill any hydrochloric acid or water.

Prediction: I predict that as I increase the concentration of the hydrochloric acid the rate of the reaction will also increase. I predict this because of the collision theory. The collision theory is when particles collide together and cause reactions. When the concentration is made stronger the particles gain more energy and this leads to more collisions and so the rate of the reaction will increase.

Results:

1.0 Molar

1.2 Molar

1.4 Molar

1.6 Molar

1.8 Molar

2.0 Molar

Conclusion: 

The variable I investigated in the preliminary experiment was the length of the magnesium strip. I found that the best length to use was 2cm because less wouldn’t fizz enough and would be too weak but more would fizz too much and would be too strong. So 2cm would give the most reliable results.

The variable which I investigated in this experiment was the concentration of the hydrochloric acid and I found out that as I increased the concentration of the hydrochloric acid the amount of gas produced increased and so the rate of the reaction increased. This is exactly what I had predicted and this is because of the collision theory.

I controlled the temperature variable because I knew that after each experiment if I had not stopped the temperature from increasing the rate of the reaction would of increased because of this as well and so my results would have been unreliable.

I controlled the temperature by placing the conical flask in cold water during the experiment so that no extra heat would be added to the results.

Evaluation:

I think that enough data was collected for definite results because the experiment was carried out with 5 different concentrations and done 3 times with each concentration. The results do support the collision theory so I think that they are good. I don’t think any of the results do not fit the pattern because as the concentration increased the amount of gas produced in the first 10 seconds would also increase but in each concentration the amount of gas produced by 60 seconds was always around 20 grams.