Question #bc581

1 Answer
Jan 16, 2018

(a) Nothing; (b) nothing; (c) a colour change; (d) evolution of a gas.

Explanation:

(a) Acetic acid + phenolphthalein

You will observe nothing.

Water is slightly acidic because it absorbs carbon dioxide and forms carbonic acid.

Phenolphthalein is an acid-base indicator. It is colourless in acidic solution.

HPh
(From Modern Soapmaking)

You are going from a slightly acidic to a more acidic solution, so you will observe no change.

(b) Acetic acid + distilled water

Both solutions are colourless. You will observe no change.

(c) Acetic acid + universal indicator

If your initial solution is neutral, the colour will be green.

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When you add the acetic acid, the colour will change to yellow or beige.

(d) Acetic acid + sodium hydrogen carbonate

You will observe the evolution of a colourless gas.

Sodium hydrogen carbonate in the presence of acid decomposes to form carbon dioxide.

#"NaHCO"_3"(aq)" + "HC"_2"H"_3"O"_2"(aq)" → "NaC"_2"H"_3"O"_2"(aq)" + color(red)("CO"_2"(g)") + "H"_2"O(l)"#