Make an Acid Indicator

1) Buy a red cabbage (紅椰菜) from supermarket (picture: http://www.chemistryland.com/CHM107Lab/Lab1/CabbageStart.jpg) and grate the cabbage into small pieces and place them in the pot + water. Boil the mixture for 20-30 minutes, until the liquid turns a dark purplish color. Decant the fluid into a glass or jar, pouring through a strainer to remove the cabbage

2) Acidic.

3) The juice should turn pink in acidic solutions, and green in basic solutions.

4) Yes, it will, please refer to the reference site.

You are a form two, right? I am a form one....
no.1====1. chop the red cabbage leaves into small pieces
=======2.put them into a beaker, cover them with water
=======3.heat the beaker and stir it until it boils. allow the liquid to cool for 15 minutes
=======4. now you have prepared the red cabbage extract which can be used as an indicator
no.2==== it is neutral (a natural indicator)
no.3====acid (pH value is less than 7): red or orange depends on the pH value of the acid, if it is a strong acid (pH value is 0) it will turn red; if it is a weak acid (pH value is 5/6) (like orange juice, apple juice) it will turn orange...
=======alkalis (pH value is more than 7): blue, blue-black or purple depends on the pH value of the alkali, if it is a strong alkali (pH values is 14), it will turn purple, weaker alkali (pH value is 10), it will turn dark blue; if it is a weak acid (pH value is 8/9) it will turn blue
====neutral (pH value is7): green
No. 4=== yes
=======add some more alkalis like, sodium hydroxide/ lime water/ ammonia solution

P.S:
Acid solutions: Hydrochloric acid/ sulphuric acid/ nitric acid or black coffee , lemon juice, acid rain , rain, vinegar
Alkali solutions: sodium hydroxide/ lime water/ ammonia solution or liquid soap, household cleaner, oven cleaner







Hope these little ideas will help you...

2008-01-25 20:44:36 補充：
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