practicals

Question 1

rate of reaction

colour change

Answer 1

1. Measure 10 cm3 sodium thiosulfate solution and put it into the conical flask.
2. Measure 40 cm3 of water. Add the water to the conical flask.
3. This dilutes the sodium thiosulfate solution to a concentration of 8 g/dm3
4. Put the conical flask on the black cross.
5. Measure 10 cm3 of dilute hydrochloric acid.
6. Put this acid into the flask. At the same time swirl the flask gently and start the stop clock.
7. 7. Look down through the top of the flask. Stop the clock when you can no longer see the cross.
      Take care to avoid breathing in any sulfur dioxide fumes.

Question 2

rate of reaction

gas

Answer 2

1. Measure 50 cm3 hydrochloric acid using one of the measuring cylinders. Pour
   the acid into a conical flask.
2. Fit the bung and delivery tube to the top of the flask.
3. Half fill the trough or bowl with water
4. Fill the other measuring cylinder with water. Make sure it stays filled with water when you invert it into the water trough and that the delivery tube is positioned correctly.
5. Add a single 3 cm strip of magnesium ribbon to the flask, put the bung back into the flask as
   quickly as you can, and start the stopclock
6. Record the volume of hydrogen gas given off at suitable intervals (eg 10 seconds) in a table
   like this