TOPIC 1. LAB ACTIVITY 2

¡The effect of temperature changes on reaction rate!

By J. Carlos Martínez1r. Batx.

BASIC INSTRUCTIONS:

MENU SAFETY Purpose and procedure. EXPERIMENTS: -Temperature 1 -Temperature 2 -Temperature 3 -Temperature 4

To avoid the danger in the laboratory, you always mustn’t smell a chemical reaction directly. Because the product can be for example: Ammonia. This smell is very dangerous for the human because is very irritant and after if you smell the ammonia you will have some ache or irritation in your nose. And remember that you mustn’t touch any substance.

PURPOSE AND PROCEDURE To observe a type of chemical reaction. To predict the products of each. To write the things that we observe.

1. Using syringes add 5 cm3 of sulphuric acid, 2 cm3 of potassium permanganate solution and 40 cm3 of water to a dry glass beaker.

2. Heat the mixture to about 40º C/50º C/60º C/70º C.3. Place the beaker on a white tale.4. Add the oxalic acid to the mixture in the beaker as

soon as possible and at the same time start the timer.5. Gently stir the reaction mixture with the thermometer.6. When the reaction mixture just turn colourless stop

the timer and record the time (in seconds). Measure and record the temperature of the reaction mixture.

7. Work out the reaction rate.8. Repeat this procedures another three times but at

higher temperatures.

MATERIALS, REQUIREMENTS

Timer Glasses Gloves Heater 3 Syringes. White paper Thermometer Distilled water Graduated Cylinder 100 cm3 glass beaker 600 cm3 glass beaker 0,2 M Oxalic acid 1 M Sulphuric acid 0,02 M Potassium

permanganate

EXPERIMENT 1

1. Place 5 cm3 of sulphuric acid and 2 cm3 of potassium permanganate in an Erlenmeyer flask.

2. Put in the 600 cm3 distilled water.

3. Put the Erlenmeyer flask into the 600 cm3 beaker.

4. Put the heater into the 600 cm3 beaker and heat the distilled water.

5. When the solution that is in the Erlenmeyer flask arrives to 40º C, we put off the flask.

6. Measure the time with the timer until the solution changes its colour.

In 40º C, the solution changed its colour in 135 seconds.

EXPERIMENT 2

1. Place 5 cm3 of sulphuric acid and 2 cm3 of potassium permanganate in an Erlenmeyer flask.

2. Put in the 600 cm3 distilled water.

3. Put the Erlenmeyer flask into the 600 cm3 beaker.

4. Put the heater into the 600 cm3 beaker and heat the distilled water.

5. When the solution that is in the Erlenmeyer flask arrives to 50º C, we put off the flask.

6. Measure the time with the timer until the solution changes its colour.

In 50º C, the solution changed its colour in 48 seconds.

EXPERIMENT 31. Place 5 cm3 of sulphuric

acid and 2 cm3 of potassium permanganate in an Erlenmeyer flask.

2. Put in the 600 cm3 distilled water.

3. Put the Erlenmeyer flask into the 600 cm3 beaker.

4. Put the heater into the 600 cm3 beaker and heat the distilled water.

5. When the solution that is in the Erlenmeyer flask arrives to 60º C, we put off the flask.

6. Measure the time with the timer until the solution changes its colour.

In 60º C, the solution changed its colour in 25 seconds.

EXPERIMENT 4

1. Place 5 cm3 of sulphuric acid and 2 cm3 of potassium permanganate in an Erlenmeyer flask.

2. Put in the 600 cm3 distilled water.

3. Put the Erlenmeyer flask into the 600 cm3 beaker.

4. Put the heater into the 600 cm3 beaker and heat the distilled water.

5. When the solution that is in the Erlenmeyer flask arrives to 70º C, we put off the flask.

6. Measure the time with the timer until the solution changes its colour.In 70º C, the solution changed its

colour in 8 seconds.

GRAPH

0 20 40 60 80 100 120 140 1600

10

20

30

40

50

60

70

80

Temperature (ºC)/Time (seconds)

Time (sec)

Temperature (ºC)

RESULTSTemperature (º C)

Time (seconds)

40º C 135 seconds

50º C 48 seconds

60º C 25 seconds

70º C 8 seconds

5(COOH)2 (aq) + 6H+ + 2MnO4- 2Mn2+

(aq) + 10CO2 (g) + 8H2O(l)

REACTION:

QUESTIONS1. State the aim of the experiment.

I think that the aim of the experiment is that we can see how afects the temperature in a solution that it is changing its colour.

2. State two factors which had to be kept constant in the experiments. The volume of the different substances and the same substances (Oxalic acid…)

3. How was the rate of the reaction determined?

The rate of reaction was determined by the temperature. If the temperature increases, the rate of reaction increases.

CONCLUSION My conclusion is this: When we increase the temperature of the

solution, the time of change colour decreases because the rate of reaction increases.