Question

Answer please

Q. What do you observe when you drop a few drops of acetic acid to test tubes containing
(a) phenolphthalein
(b) distilled water
(c) universal indicator
(d) sodium hydrogen carbonate powder

Answer 1

a)phenolphthalein -- no change
b)distilled water-- no change
c)universal indicator-- colour will change to orange

d)With sodium bicarbonate

NaHCO3 + CH3COOH-------->CH3COONa+H2O+CO2
so there will be brisk effervesence

Answer 2

Hi Friend !!!

Acetic acid show acidec behaviour . It breaks and give H+ ions . These H+ ions shows the acidic behaviour in indicators.

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( a ) Phenolphthalein :

Phenolphthalein is usually colourless in neutral and acid. It turn pink in base.

So here , Phenolphthalein will be 'colourless' as we add an acid.

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( b ) Distilled water :

Both Distilled water and acetic acid are weak acids . Both doesn't dissociate full.
Thus solution remains neutral.


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( c ) Universal Indicator :

The solution will be orange - yellow as pH of acetic acid is 4.76


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( d ) Sodium hydrogen carbonate powder

CH3COOH + NaHCO3 ----> CH3COONa + H20 + CO2

This reaction takes place. ( Neutralisation reaction )

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Hope it helps