Temperature's Effect on Chemical Reaction Rate

Hypothesis

If temperature increases then the rate of reaction between the reactants will increase because the molecules will gain more kinetic energy and make it easier to overcome the activation energy.

Independent Variable: Temperature

Dependent Variable: Product produced in a set time

Constants: Time, concentration

Materials:

1. Hot Plate
2. Hydrochloric Acid (1 mol)
3. Calcium Carbonate
4. Cylinder ±0.1 ml
5. Stopper
6. Timer ±0.1 sec
7. Thermometer ±0.1 C
8. Tube for Stopper
9. Clamp
10. Beaker 0.1 ml
11. Water
12. Flask
13. Scale ±0.1g

Procedure

• Fill the cylinder with water.
• Fill 2000 ml beaker with water.
• Tip the cylinder upside down, without losing any water, into the 2000 ml beaker.
• Clamp odometer about 2 in above the bottom of the beaker to the ring stand.
• Put the tube inside the cylinder and have the stopper ready for the flask.
• 6Measure out 5 ml of hydrochloric acid of 1 mole and dilute it in 80 ml of water and fill it in the beaker.
• Check if the hydrochloric acid is about room temperature (22° C) with the thermometer. If not, put the beaker on the hot plate to heat it to the right temperature.
• Measure out 1 g of Calcium Carbonate.
• Fill the flask with the Calcium Carbonate
• Fill the flask with the hydrochloric acid and start the timer. Quickly put the stopper on the flask.
• Hold the flask and lightly stir it for 4 minutes.
• After the 4 minutes record the displacement made.
• For the rest of the variables (32° C, 43° C, 52° C, and 62° C), repeat steps 3-12 but on step 7. Make sure you heat it to the right temperature.

General Observations:

1. Temperature was hard to keep constant
2. If you stir differently every time then the amount of gas produced varies with every trial.
3. Some gas was lost when putting both the Calcium Carbonate and the Hydrochloric acid because the stopper needs to be on at a faster time. There was no way to have the stopper on instantaneously with both the reactants.
4. Calcium Carbonate is sticking to the container that it was put on.
5. There was a correlation between the amount of gas produced and the change in temperature.

Calculations:

The balanced equation:

CaCO3(s) + 2 HCl(aq) = CaCl2(aq) + CO2(g) + H2O(l)

(Using variable 1): Trials: 5.7 ml, 5.9 ml, 6.0 ml

Add them all together: 5.7 + 6.0 + 5.9 = 17.6

Then divide it by 3: 17.6 / 3 = 5.9

Conclusion and Evaluation:

Overall, my data supports the hypothesis I have made. There was a correlation between the temperature and the amount of gas that was produced. As the temperature increased, the amount of gas produced increased because the reactions are taking place at a higher rate. There were a lot of random errors in this experiment such as the gas that was lost during the experiment. The reason was because of the amount of time it takes to pour the HCL into the flask and also the amount of time to put on the stopper makes the results inaccurate, because gas is being lost to the outside and we cannot measure that, but in the end it still have similar results. In the graph it shows that the percent of increase was low but as we get to 52° C the percentage became higher. I believe that around the 42 – 52° C range is when the temperature is high enough to overcome the activation energy, that is why the gas produced is at a much higher at the 52 – 62° C range than the 22 – 42° C range. The systematic error in this experiment is the temperature, because the temperature fluctuates as I cannot get the temperature perfect with every experiment.

I believe the procedure was followed really well but the whole set-up is really time consuming. The hardest part of the experiment was turning the cylinder upside down while not trying to lose any water. Also, there was the problem of pouring the HCL inside the flask with the Calcium Carbonate then putting the stopper on, because, as I addressed before, it was losing gas to the outside which cause inaccuracy in the data. There was also the issue of stirring. I have noticed that every experiment the stirring rate is different which is caused by me.

There were many limitations in this experiment, such as the instruments that were used and because of the instruments that were used, the precision of the experiment is decreased. There was also the temperature, which is a factor that was hard to keep constant because the temperature fluctuates and also the thermometer is not too precise. To improve this experiment I need better instruments that can measure with more precision. Also find a way so when we tip the cylinder upside down, no water is lost during that process and finding a way to lose no gas that was produced while in the process of pouring in the HCL and putting the stopper on.