Sodium Thiosulphate and hydrochloric acid

Transcription

1 Sodium Thiosulphate and hydrochloric acid Introduction The rate of reaction can be altered by varying temperature or concentration, or by changing the surface area of a solid reactant, or by adding a catalyst. You are going to investigate the reaction between hydrochloric acid and sodium Thiosulphate whose rate depends on temperature. You can repeat this experiment at several temperatures: 20 o C, 30 o C, 40 o C, 50 o C and 60 o C. To measure whether the reaction takes place, you can use a Light sensor or a Colorimeter. This Logbook can measure the absorption and so, the turbidity of the solution. On the left column, you will see the instructions to carry out the experiment with the Light sensor and on the right one, with the Colorimeter. Apparatus Datadisc Au A lamp Two 40 ml beakers 100ml beaker Logbook ML, SE or XD with a Light sensor A cuvette A five-pin din cable Colorimeter (Logbook CM) Logbook ML, SE or XD A serial lead or USB-serial lead Temperature probe 0.1M Hydrochloric acid 0.1M Sodium Thiosulphate A water bath A 20ml syringe Duration 1h30

2 Method 1. Plug the Logbook into the PC using a serial lead or USB-serial lead. 1/ Plug the Temperature probe into port 3 or, if you are using Logbook XD, plug the Light sensor into port 1 and the Temperature probe into port Measure out 50ml of 0.1M Sodium Thiosulphate with a syringe and pour it into a 40ml beaker. 4. Measure out 5ml of 0.1M Hydrochloric acid in a syringe and pour it into another 40ml beaker. 5. Place the two beakers in the water bath at the temperature chosen. 2. Plug the Colorimeter CM into the Logbook (port 1 or 3 according to the Logbook you are using) using a five-pin din cable. Plug the Temperature probe into port 2 or Turn on the Colorimeter by pressing any button. You will see the ScienceScope splash screen and then the Not calibrated screen. 4. Place a cuvette filled with distilled water in the Colorimeter the right way round. 5. Press. You will see the Calibrating screen. 6. The frequency you use doesn t matter because you are not going to measure colours. Choose the Transmission (Tx) with. 9. Start Datadisc Au. 7. Measure out 3ml of 0.1M Sodium Thiosulphate with a syringe and pour it into a cuvette. 8. Place the cuvette in the water bath at the temperature chosen. 10. Click on Measure and then click on Meter. A menu will appear asking you to choose channels to meter. 11. Click on OK. You will see the light level reading or the transmission and temperature readings. 12. Remove the reading you don t need (Ch1: Temperature) if you are using Logbook SE or ML. 12. Remove the readings you don t need (Ch1: Temperature, Light level) if you are using Logbook SE or ML. 13. Check the temperature of the Sodium Thiosulphate and wait for it to reach the chosen level. 14. Close the Meter window. 15. Click on Measure.

3 16. Click on Auto time. Then the Recording window will open. 17. Choose the channels you want to measure on the toolbar if you are using Logbook ML or SE. 18. To make the recording: a. Place the lamp above the Light sensor and switch it on. a. Prepare about 0.3ml (8 drops) of 0.1M Hydrochloric acid in a syringe. b. Click on the green recording icon on the toolbar: this starts the recording. c. Start the experiment: place the beaker with the Sodium Thiosulphate on the Light sensor, place the Temperature probe inside and pour the acid into it. c. Start the experiment: add the acid in the cuvette containing the Sodium Thiosulphate, mix it and place it in the Colorimeter and put the lid on. Leave the Temperature probe in the water bath. d. Stop recording by clicking on the red hand when the light level or the transmission stops changing. e. The graph should show you a decrease of light level or transmission. 19. Click on Keep this data. 20. Switch off the lamp if you are using it. 21. Remove the Temperature probe from the solution and rinse it off. 22. You can repeat the experiment at another temperature. How to save your recording 1. Click on File. 2. Click on Save as. 3. Choose the directory you want to save in and type the name of your file. 4. Click on Save. How to select a part of the graph 1. Click on Data. 2. Click on Select part. You will have a message from Datadisc Au.

4 3. Read it and click on OK. 4. Select with the mouse the part of the graph you want to keep. How to amend the range of the temperature graph 1. Click on Graph. 2. Click on Scale. 3. Click on Direct entry. 4. Choose the lower limit 0 and the upper limit 100 for the Temperature. 5. Click on OK. How to find the rate of the reaction 1. Click on Graph. 2. Click on Cursor. 3. Click on Gradient. 4. Click on the light level graph where the curve decreases. The gradient will be displayed at the top of the window. How to represent the graph of gradient against temperature 1. Click on Measure. 2. Click on Spreadsheet entry. 3. Enter the data.

5 4. Click on File. 5. Click on Update. How to amend the graph 1. Click on Graph. 2. Click on Plot options. 3. Tick Join points. 4. Click on OK. How to store information about your recording 1. Click on Data. 2. Click on Data information. 3. Type all the information you want in Data title and Data information. 4. Click on OK.

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7 How to save your file and exit 1. Click on File. 2. Click on Save. 3. Click on File. 4. Click on Exit.