Reaction with metals
3 marks · EasyEthanoic acid is a weak acid.
State the colour change seen when blue litmus paper is placed in ethanoic acid.
Explain what is meant by the term "weak acid".
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) Turns red
(b) A weak acid only partially ionises in water. · must show Partial ionisation, Does not release all H+ ions
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · States that blue litmus turns red or pink in ethanoic acid.
B1 (b) · 1 mark · States that a weak acid is only partially ionised (or dissociates/ionises partially) in water.
B2 (b) · 1 mark · Mentions that not all H⁺ ions are released or only some acid molecules ionise.
Worked solution
a) Blue litmus paper turns red in ethanoic acid since ethanoic acid is acidic.
b) A weak acid is an acid that is only partially ionised in water. This means that only a fraction of the acid molecules release hydrogen ions (H⁺), while the rest remain as molecules.