# The magnesium strip

The chemical equation for this experiment is

Mg + 2HCl MgCl2 + H2

## Prediction

My prediction on this experiment is when the temperature is kept at low degrees the reaction of magnesium strips with HCl will be slower but when the temperature is raised to a higher degree the magnesium strip will react with HCl much faster. So when the particles move faster they would have more collisions between them. In cold temperature In hot temperature Example when magnesium strip is set to react with HCl at 10 degrees the reaction will be much slower compared to when the magnesium strip is set to react with HCl at 60 degrees.

## Preliminary Test I

Preliminary Test I have carried out preliminary test to make sure that my experiment will go right. In my preliminary test we done the same type of experiment which we will be doing for out final one. After conducting this test we found out that the test was correct and so now we could do a real experiment

### Method

1. I had to setup all the apparatus which were needed in the experiment
2. Place some water into a bowl then add some ice to it to make the temperature to 10 degrees because we will be that is the temperature we need to start our experiment with
3. Record 10ml of HCl on a test tube
4. Cut out around 20 magnesium strips at one centimeter each
5. Once the water is set at 10 degrees then I had o put the test tube on the beaker holding it by the clamp and stand
6. Once we put in the Mg strips we have to start the stopwatch
7. When the Mg strip has been fully dissolved I had to stop the stopwatch
8. Check the reading on the stopwatch and record it
9. After the reaction is over take out the test tube and wash it thoroughly leaving back no HCl
10. Then again add 10ml of HCl on to the test tube once it becomes dry
11. Repeat the same reaction 2 more time.

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12. Then instead of 10 degrees of water we will increase it by another 10 degrees so it now will be 20 degrees
13. For the same steps above I had to carry out the reaction again
14. Every three times of same reaction I had to do the reaction with a higher 10 degrees of water into the bowl. The highest we will be going is 80 degrees
15. I had to keep in mind that between each reaction I had to take the results and without them I would have to do the reaction again

To find the average number of time taken I had to use a formula which was: Time 1 + Time 2 + Time 3

## Conclusions

My predictions were correct that when the temperature increases in a rate of reaction the reaction goes much faster. You can also see this from the table of result on top that at 100 the average time is 60 seconds and when you will look at 800 the reaction took only 37 seconds Accuracy of Results Although there were some anomalous results in my first set of readings I think that overall the accuracy was sufficient for the experiment as the pattern shown by my results and my conclusions are supported by the collision theory.

## Evaluation of the Experiment

I think that this experiment worked well, as the results fit with my hypothesis and are supported by the collision theory. Errors There is one suspected anomalous readings in my results from this investigation taken in the first set, for the temperature of 30i?? C (see Table 1) The anomalous readings from the first set give slower reaction rates for increased temperature which is not a trend shown by any other results. The second set of results taken show the trend predicted in my hypothesis of increased reaction rate as temperature increases.

These anomalous readings could be due to a number of reasons as follows: –

1. Errors timing the reaction length with the stopwatch – deciding when to stop the stopwatch to mark the end of the reaction was difficult as the magnesium floated to the surface causing bubbles making it hard to know when the reaction had finished.
2. Variation in the shape of the magnesium ribbon – if the ribbon was twisted or misshaped it could make the hydrogen bubble effects discussed in my analysis above more significant.
3. Errors in measuring the length of magnesium, longer lengths would give an increased reaction time.
4. Failing to stabilize the temperature of the acid, if the temperature of the acid were higher at the bottom of the flask than at the top where the reaction is taking place this would give anomalous readings.
5. Errors reading the burette – if there were less acid this could increase the reaction time.
6. Temperature of the magnesium at the start of the reaction – if it had been cooler this could have slowed the initial rate of the reaction. Improvements.

We could improve our experiment in many ways such as improving the method of timing how long it takes the ribbon to dissolve by looking at the ribbon very carefully without any distraction and closely using goggles which would help us to know when exactly the ribbon got dissolve. Other improvements could be to do the experiment on a water heater except doing in the bowl because we can keep the temperature at a steady rate, which it needs to be on.

### Aim

My aim to this experiment is to discover whether different surface area affects the rates of reaction

### Apparatus needed

• Electronic Balance
• Motor and Pistol
• Stopwatch
• Calcium Carbonate
• Cotton wool
• Hydrochloric Acid

Fair test In order to keep a fair test, only the surface area (i. e. size) of the marble chips and powder is variable. Other variables are to be kept constant to avoid obtaining wrong results. These other variables include:

• Temperature: -temperature of the reactant is kept at room temperature.
• Volume of acid: – the volume of acid is kept constant at level
• Concentration of acid: – the concentration of acid is kept same throughout
• Surface area of the conical flask: – the size of the conical flask is kept same

The HCl cannot be used again after the reaction because the acid becomes less strong to react with the acid. I need to be accurate in taking my readings as an inaccurate reading may cause errors and alter my results. The surface area of the chips needs to be appropriate and vary in different experiments to get the correct rate of the reacting size The word equation for this reaction is Calcium carbonate + hydrochloric acid calcium chloride + water +carbon dioxide The chemical equation for the reaction

CaCO3(s) + 2HCl(aq) CaCl2 (aq) + H20 (l) + CO2 (g).

## Prediction (activation energy and collision theory)

I predict that as the size of particles decreases, surface area will increase causing the average collision of particles to increase. Which means that the powdered chips will react faster. An increase in rate of collision causes an equal increase in the rate of reaction. This is based on the collision theory that states that for a reaction to occur between two particles, an effective collision must take place to form product molecules. The reaction rate is the measure of how frequently effective collisions occur.

In chemical reactions, existing bonds in the reactant particles have to be broken down first before new bonds are formed to produce product particles. Reactions only occur if colliding particles have more than a minimum amount of energy. This energy is known as activation energy (EA). It acts as a sort of ‘energy barrier’ unless particles have more energy than the activation energy, the reaction cant take place. As a result, of increase in surface area, I predict that there is greater area for contact between the powder and the acid for reactions to take place therefore increasing rate of reaction.

The rate simply depends on how fast and often particles collide with each other. The increase in surface area also results an increase in the rate of reaction. The most concentrated substances the faster that reaction would be. The more surface area will allow particles to move more freely and have more collisions Small Surface large surface area area the smaller the marble chips are the increase in surface area so it also means reactions has to increase.

### Safety

• Wear goggles to prevent dangerous substances (such as acid) from entering eyes as it can cause damage to the eyes.
• Handle acid product with responsibility as it is a harmful product and it is corrosive when it meets skin.
• If gas syringe is used instead of gas generator and measuring cylinder, gas syringe should be watched while collecting gas as the syringe may fall out of the end and break if too full.
• Marble chips (small or large) can be inhaled or wedged in body organs or openings E. G. ears or eyes and this is dangerous.
• Be careful pouring acid into the beaker Method The steps of method will show the way in which I done my experiment
1. First we need the calcium carbonate into powder by using the mortal and pistol
2. The powder should be measured by using the electronic balance. It should be weighed about grams
3. 100 ml of acid should be added to the conical flask
4. Put the flask on the electronic balance and then make the reading on the electronic to ” 0 “
5. Now pour powdered form of calcium carbonate into the flask
6. As soon as the reaction begins start the stopwatch
7. Then immediately we kept a cotton wool on top of the flask
8. Keep taking the record of the weight every minute
9. Keep the reaction till 10 minutes and stop the experiment and record the final weight.
10. Now we had to use the chips instead for the powder of calcium carbonate
11. For this reaction do the same steps above and note down the recordings
12. Finally I had to put the two results on two different tables. 1 for the powder and the other for the chips

From the results of my experiments I observed that each of the reactions start of fast but start to slow down after some time. A reaction is exothermic if heat energy is given out during the chemical change, and the surroundings get hotter.

On the following pages there are two graphs showing the rates at different surface areas. And another graph with both the reaction compared Conclusion In this experiment my aim was to see which type of surface area gives the fastest rate of reaction. I have succeeded in doing so. I recorded the rates of reaction using different sizes of particles. My predictions matched and concluded with my results, as you can tell from the graph, I have proved that the smaller the size of marble chips the faster the rate because the surface area is more and more collisions take place per second.

The particles of hydrochloric acid (HCl) and calcium carbonate (CaCO3) react by colliding with each other. Although the chips are the same mass with powdered chips, it has less surface area. In the graphs, I saw distinct patterns: they all have positive link that illustrates that they all have the same trend. The graphs are more efficient in describing the same effects as that of the tables because it shows clearly that the smaller the size of particles, the faster the rate of reaction. Evaluation I think my experiment was successful as I was able to obtain the evidence I needed to achieve my aim.