Effect of temperature on the rate of reaction between sodium thiosulphate and hydrochloric acid

In this article, we have discussed the effect of temperature on the rate of reaction between hydrochloric acid and sodium thiosulphate.

Aim:

The aim of this experiment – Understanding the effect of temperature variation on the rate of reaction between hydrochloric acid and sodium thiosulphate.

Theory:

The rate of a chemical reaction is directly proportional to the temperature. As the temperature increases, the reaction rate also increases. With the increase in temperature the kinetic energy of the molecules also increases. Usually, it is observed that for every 10-degree increase in temperature the rate of reaction is doubled. Therefore, the rate of reaction of hydrochloric acid and sodium thiosulphate also increases with rise in temperature.

Materials required:

The apparatus and materials required for this experiment are as follows:

1. Conical flask of volume 250 mL
2. Stop-watch
3. Tripod stand
4. Measuring cylinder
5. Stopwatch
6. Burner
7. Thermometer
8. Wire gauze
9. 0.1M sodium thiosulphate solution
10. Concentrated nitric acid
11. Distilled water
12. 1M hydrochloric acid

Procedure:

The effect of temperature on the rate of reaction:

1. Take a conical flask of volume 100 mL.
2. Add 50 mL of 0.1M sodium thiosulphate solution to it.
3. With the help of a thermometer measure, the temperature of the solution which is added to the flask.
4. Take 1M HCl of volume 10 mL with the help of a burette and add it to the conical flask containing sodium thiosulphate.
5. Start the stopwatch as soon as you have poured half of the hydrochloric acid into the flask containing sodium thiosulphate solution.
6. Take a white tile and draw a cross mark on it.
7. Shake the conical flask and place it on the tile.
8. Observe the flask and start the stop-watch as soon as the cross mark becomes invisible.
9. Empty the flask and wash it with concentrated nitric acid first and later with distilled water.
10. Take the washed flask add 50 mL of 0.1M sodium thiosulphate solution and heat it to (T+ 10)°.
11. Continue the steps from points 4.
12. Repeat the experiment for (T+ 20) °C, (T+ 30) °C, (T+ 40) °C and record the results.
13. Record the time taken for the process.

Observation and result

Precautions to be taken during the experiment:

• Thoroughly wash the apparatus with concentrated nitric acid and distilled water.
• Take the exact quantity of solutions needed for this experiment.
• Complete the experiment in one go to avoid temperature variations.
• Use THE same tile for all the observations.
• Stay alert while you start and stop the stop-watch.

Viva Voce:

1. What is the concentration of sodium thiosulphate used for this experiment?

Ans: 0.1M.

2. What is the concentration of hydrochloric acid used for this experiment?

Ans: 1M.

3. When to start the stop-watch?

Ans: As soon as you pour half of HCl into the flask containing sodium thiosulphate solution.

4. Name the two solutions used in this experiment.

Ans: Hydrochloric acid and sodium thiosulphate.

5. What is the importance of concentrated nitric acid?

Ans: It is used in thorough washing of the apparatus used in the experiment. After washing the apparatus with HNO₃ rinse it with distilled water.