Carboxylic acidsIB MYP Chemistry: Mind map

Exam questions on Carboxylic acids

1. A teacher writes the formulae HCOOH, CH₃COOH, C₂H₅COOH and C₃H₇COOH on the board. They are the first four members of a family of organic compounds.
   Explain why ethanoic acid is a weak acid, whereas hydrochloric acid of the same concentration is a strong acid.2 marks
2. A student investigates how ethanoic acid reacts with different substances: magnesium ribbon, calcium carbonate and sodium hydroxide solution.
   Write the word equation for the reaction between ethanoic acid and sodium hydroxide.2 marks
3. A student compares ethanoic acid and hydrochloric acid, each with a concentration of 0.10 mol dm⁻³. She measures the pH of each acid with a pH meter. She then times how long a 2 cm strip of magnesium ribbon takes to dissolve completely in 50 cm³ of each acid at 20 °C. Hydrochloric acid had a pH of 1.0 and the magnesium dissolved in 40 s. Ethanoic acid had a pH of 2.9 and the magnesium dissolved in 210 s.
   State a testable hypothesis that the student could have been investigating, and include a scientific reason for it.3 marks