Carboxylic Acids
5 marks · EasyMethanoic acid is the first member of the carboxylic acid homologous series.
Draw the displayed formula of methanoic acid.
Name the salt formed when methanoic acid reacts with magnesium.
Write a balanced chemical equation for the reaction between methanoic acid and magnesium.
What would you observe during this reaction?
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.
Show answer
(a) Displayed formula: H–C(=O)–O–H, showing all bonds, with one C atom double-bonded to O and single-bonded to another O–H. · must show all bonds, -COOH group drawn fully, single C atom
(b) Magnesium methanoate
(c) Mg(s) + 2HCOOH(aq) → (HCOO)2Mg(aq) + H2(g) · must show state symbols, balanced, correct formulae
(d) Fizzing or effervescence; bubbles of hydrogen gas seen.
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Fully correct displayed formula showing all bonds for methanoic acid (COOH group clear)
B2 (b) · 1 mark · Correct name: magnesium methanoate
M1 (c) · 1 mark · Correct reactants and products, even if unbalanced (follow-through)
A1 (c) · 1 mark · Fully balanced chemical equation with correct formulae and state symbols
B3 (d) · 1 mark · Correct observation: fizzing/effervescence or hydrogen gas given off
Worked solution
a) The displayed formula of methanoic acid is:
b) The salt formed is magnesium methanoate.
c) The balanced equation is:
d) You would observe fizzing or effervescence due to hydrogen gas being produced.