Acidic Environment Pracs

Question 1

whats the procedure for preparing a natural indicator?

Answer 1

1. Cut or grate a portion of a red cabbage, placing the small pieces into a large beaker and add
   enough boiling water to the beaker to cover the red cabbage (or use room-temperature water
   and heat with a Bunsen burner).
2. Allow the red cabbage pieces to boil for several minutes, not stopping until the water has
   become a dark, reddish or purplish colour.
3. Decant or filter the mixture into another beaker. Record the colour of the indicator obtained.
4. Test various substances with the indicator and record any changes in colour. Some substances
   you may wish to test include baking soda, vinegar and house salt (NaCl).

Question 2

what are the results in the natural indicator prac?

Answer 2

When an acidic substance is added to the indicator, the resultant colour should be pink. When a
basic substance is added to the indicator, the resultant colour should be green. Between these two
colours, the colour should be purple.

Question 3

whats the procedure for decarbonating soft drink?

Answer 3

1. Record the weight of a bottle of soft drink.
2. Shake the bottle slightly, opening it carefully to release the gas without spilling the contents.
   Repeat this step until shaking ceases to have a noticeable effect.
3. Remove the cap, and immerse the bottle in a warm bath for several minutes.
4. Remove the bottle from the bath and leave it overnight in a place away from sources of
   evaporation.
5. Replace the cap and reweigh the bottle and record its weight.
6. Calculate the volume of carbon dioxide gas released.

Question 4

whats the go with testing the pH of solutions with a ph probe?

Answer 4

pretty straight forward, just get equal volumes of solution and test each with a probe that has been correctly calibrated using standard solutions of known pH

Question 5

whats the procedure for determining the concentration of a domestic acidic substance using computer based technologies?

Answer 5

1. Prepare beakers of a variety of domestic acidic substances such as vinegar, lemon juice and
   milk.
2. Calibrate a pH probe.
3. Place the probe gently into each beaker in turn, taking care to dip the probe in the buffer in
   between each test so as to avoid distorted results.
4. Record your results.

Question 6

whats the procedure for preparing an ester using reflux?

Answer 6

1. Place 10-20ml of ethanol and an equal amount of the ethanoic acid into a 50ml flask.
2. Add 1ml of concentrated sulfuric acid into the mixture of reactants, and then add a moderate
   amount of boiling chips.
3. Gently clamp the flask and refluxing apparatus onto a retort stand, dipping the flask into a
   water bath.
4. Run a hose through the refluxing apparatus, ensuring water is entering through the bottom
   and exiting through the top. This ensures that water is always present in the cooling jacket,
   even if the water supply stops.
5. Heat the water bath using either a Bunsen burner or a hot plate, and reflux the mixture until
   two discernible layers form.
6. Add 50ml water into the remaining mixture, and pour into a separating funnel. Remove the
   lower layer. The remaining mixture should be a relatively pure ester. Sodium bicarbonate can
   be used to neutralise any excess acid if desired