Carboxylic acid investigation

Experiment

Observations

Inferences

1. Put 1cm³ of water into a test tube. Add one or two drops of ethanoic acid.

Mixes with water

Ethanoic acid is soluble in water

2. Put 1cm³ of water into a test tube. Add one drop of UI solution. Add one or two drops of ethanoic acid.

Green → Orange (pH 3)

Ethanoic acid is a weak acid

3. Put 1cm³ of water into a test tube. Add one piece of pH paper. Then add five drops of water.

Stays green until water is added

Ethanoic acid only acts as an acid in the presence of water

4. Put 1cm³ of ethanoic acid in a test tube. Add one piece of Mg ribbon. Then add five drops of water.

Effervescence, white precipitate, water added = more fizzing, Mg gone

H₂ gas produced

Acid + Metal reaction

5. Put 1cm³ of ethanoic acid in a test tube. Add one spatula of anhydrous Na₂CO₃ crystals. Then add five drops of water.

Lots of effervescence.

Water = effervescence

CO2 gas produced

Acid + carbonate

6. Put 10cm³ of 2M NaOH in an evaporating dish. Add 5cm³ of ethanoic acid in a test tube.

Got warmer

Neutralisation

Acid + Alkali → Salt + water

7. IN THE FUME CUPBOARD. Put 1cm³ of ethanoic acid in a boiling tube and add 1 spatula of PCl₅.

PCl₅ dissolves, acidic gas released

Damp UI paper turned red

Acyl chloride formed

It reacted with moisture in air to form HCl gas