To investigate the effect of temperature on the rate of reaction

Surface area of a solid reactant

The surface area of the solid reactant can affect the rate of reaction. This is because the two types of molecule can only bump into each other on the surface of the solid. Therefore, simply, the larger the surface area of the solid, the faster the reaction will be.

Variables

        

My preliminary consists of me measuring the rate of reaction at two specific temperatures: 70°C and 0°C. Additionally, I will be reacting two sizes of calcium carbonate chips; small and large. As mentioned, the smaller chips have a larger surface area and so will react faster. The amount of acid that I will be using is 30cm cubed. The volume of marble chips will also be same (one spatula full). The time intervals that I wish to use in this experiment is 10 seconds.

This is because this experiment involves reacting the HCL with CaC03 and then calculating the volume of carbon dioxide that is given off. I will be monitoring the volume of gas produced every ten seconds and recording that volume at that time.

Finally I will take more than the minimum readings of 7 and take 10. I will also retake these readings three times for each stage. This is because if I make an anomalous result than I have three chances to get it right and the average of all three will then become closer to the actual result which should be sufficient as a final reading.

Equipment list:

• Calcium carbonate (small chips, large chips)
• Hydrochloric acid
• 1 Spatula
• 1 Measuring cylinder
• Ice
• 1 Conical flask
• Beaker
• 1 Kettle
• 1 Thermometer
• 1 Clamp stand
• 1 Gas syringe
• Water
• 1 Stopwatch
• Pen/paper to record

Preliminary Method:

1. (a) For 70°C; using the kettle, heat some water, put it in the beaker and use the thermometer to read when the temperature is at 70°C.

      (b) For 0°C; put ice in the beaker, and the temperature is at 0°C

2. Put the conical flask in the beaker.
3. Add one spatula of chips in the conical flask.
4. Set up the syringe on the clamp stand with the stopper just above the conical flask; make sure the syringe is at the 0 on the meter.
5. Measure out 30ml of hydrochloric acid.
6. Add it quickly to the conical flask, closing the stopper straight away and starting the stopwatch immediately.
7. Every 5/10 seconds, record the amount of gas that has built up in the syringe; until it reaches 100, at which we stop the experiment.
8. Repeat the experiment (at 0°C and 70°C) for both small chips and large chips.

Preliminary Results:

Temperature at 0°C

 

Temperature at 70°C

Errors in Preliminary

I have also decided to keep the amount of HCL at 30ml.

Equipment List:

• Calcium carbonate (medium chips) – the solid reactant
• Hydrochloric acid – the liquid reactant
• Spatula – to measure out accurate amounts of marble
• Measuring cylinder – to accurately measure the 30ml of hydrochloric acid
• Ice – to make the temperature fall accordingly for the 0°C part
• Conical flask – for the reaction to take place in
• Beaker – to put in cold/hot water to change the temp. of solution
• Kettle – to heat the water
• Thermometer – to check the temperature
• A clamp stand – to hold the gas syringe in place
• Gas syringe – to collect any gas produced, and allowing us to record the volume
• Water – for varying the temperature of the solution
• Stopwatch – to time the reaction
• Pen/paper – to record results

• Goggles  – to protect my eyes in case I spill the HCL

Method for real experiment:

1. (a) For over 0°C; using the kettle, heat some water, put it in the beaker and use the thermometer to read when the temperature correct.

      (b) For 0°C; put ice in the beaker, and let it set so that the conditions are ideal; check with the thermometer that the temperature is at 0°C

2. Put the conical flask in the beaker.
3. Add one spatula full of medium chips in the conical flask.
4. Set up the syringe on the clamp stand with the stopper just above the conical flask; make sure the syringe is at the 0 on the meter.
5. Measure out 30ml of hydrochloric acid.
6. Add it quickly to the conical flask, closing the stopper straight away and starting the stopwatch immediately.
7. Every 10 seconds, record the volume of the gas in the syringe until the syringe becomes full.
8. Repeat the above steps twice more, the 2nd and 3rd readings.
9. Increase the temperature by 10°C accordingly and repeat steps 1-8.
10. Repeat step 9. until you reach a set of results up to 70°C.

Diagram

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Analysis     

My results suggest that as the temperature gets colder, the longer it takes for the solution to react; meaning a slower rate of reaction. My graph clearly shows a positive correlation and it is evident that when the temperature was high, the curve was steeper than when the temperature was low. My results suggest that the hotter the temperature, the faster the reaction. When particles are heated they gain more kinetic energy, so they move around faster and will collide more; thus increasing the likelihood of successful collisions. They also overcome the energy barrier, so more molecules have greater energy than the energy needed to activate the reaction.

At 50 seconds, 89ml of CO2 was given off when the solution was 70oC. At 50 seconds, 53ml of CO2 was given off when the solution was 40oC. This shows that when the solution was at a low temperature, less CO2 was produced in the reaction.

To find the rate and reaction, I divided the y point by the x point. To work out the rate of reaction, I chose a point (55 ml) on the y-axis, and joined it to the curve, then to the x-axis. I drew tangents and then read the point off the curve.

Rate of reaction = y/x

      This table shows that as the temperature got hotter, the rate at which CO2 was being produced increased, thus more millilitres of CO2 was being produced per second.

       When the solution was at 70oC, the rate of reaction was 2.75 Vm/sec-1 and when the solution was 40oC, the rate was 1.1Vm/sec-1. This was because when the temperature was higher, particles had more kinetic energy, collided more and had more energy than that of what is needed to activate the reaction. As a result of this, it was more likely that the particles collided successfully. My prediction corresponds to my results very closely, as my results show that as the temperature lowers, it takes longer for the solution to react and produce 100ml of carbon dioxide in the syringe. Although the results are consistent and verify my prediction, they do not support my quantitative prediction. My numerical prediction was that as the temperature doubles, the rate of reaction would also double. For example, at 20oC, the rate of reaction was 0.47 Vm/sec-1, which doesn’t double when the temperature was 40oC, as the rate of reaction at this point was 1.1 Vm/sec-1.

Evaluation

      I think the procedure I used wasn’t exactly the best to get the most reliable and accurate evidence. However, considering the circumstances my results came out better than I had expected. My prediction was correct as my results showed that as the temperature got colder; it took longer to produce the carbon dioxide. The particles in a colder solution do have enough energy to collide and activate a reaction but in a solution where the temperature is warmer, more particles have more energy than the activation energy and overcome the energy barrier. If more particles have more energy, they are more likely to collide successfully.

      My results are quite good with only 2-3 seconds (sometimes even less or none) between readings, which mean they are fairly accurate.

      There were more anomalies when the temperature was colder, as I found 0oC, 10oC and 20oC, hard to control. With the 0oC, the points in the graph are too low which meant that not enough carbon dioxide was being produced. This may have been due to the temperature was too cold or because there weren’t enough marble chips so there was less to react, or there could have been not enough HCl2. With 10oC and 20oC, some of the anomalies were too high, which meant that too much CO2 was being produced. This could have been because the temperature was too warm or there were too many marble chips and more to react. It also could have been because there was too much hydrochloric acid.

      I think my method was fairly suitable but could be bettered by improving the way we used the equipment and managed out time.

      I believe my results were quite reliable because the readings were close and consistent. If I repeated the experiment, I feel I would find similar results (though not exactly the same).

      My results are accurate enough to support my forecast that as the temperature increased, the reaction rate was much quicker. However, I do not think that my test was as fair as it could have been. The temperature was not kept constant for every reading. It may have been too low or high by a few oC each time. As the experiment was carried out over three days; the same beaker of HCl was also not used each time, so it may have been more or less concentrated on different days, meaning that it may have reacted too much or too little and rendered the experiment a little inconsistent. The amount of marble of chips might have differed because we used the spatula to take out the calcium carbonate. This means that a different amount of solute was added each time. Additionally, the gas syringe may have affected the fairness of the results, because from time to time it would stall and jump suddenly, which means that some carbon dioxide may have been either escaping or simply because the slide in the syringe was not as mobile as it should have been.

Anomalies

On the 20oC curve, the points were too low:

• As the temperature was too low
• Not enough marble chips
• Not enough HCl2

If the temperature was too low, the particles would not have had enough kinetic energy to move around and successfully collide with other particles and react. It also meant that not a lot of molecules had energy more than the energy barrier which is why not enough CO2 was produced; therefore the points were too low.

      If I were to repeat this experiment, or extend it, I would change numerous variables to explore the investigation further. The Mass Loss method could be tried; this is where we measure how much mass is lost from the marble chips and use this to calculate the rate of reaction.

To extend this investigation further I could: increase the temperature range, or change the reactants (change CaCO₃ and  HCl) etc.