How esters are made and hydrolysed, saponification of fats and oils to make soap, how soap and soapless detergents work, and how they compare in hard water and in their environmental impact.
5 narrated scenes. Press play, listen and read along — the points appear as they are explained. Use ‹ Prev / Next › or the scene bar to jump to any scene.
Soap is one of the oldest chemical products. It is simply the product of an ester being broken down with an alkali.
Narration uses your device’s built-in voice. No sound? Switch to “Captions only” — the captions advance on their own.
Find the ester link, then compare the tail and the head of a soap ion.
Copy these into your notebook in your own words — that is how they stick.
Acid + alcohol ⇌ ester + water; conc. H₂SO₄; warm.
Alcohol part first: ethyl ethanoate.
Ester + water → acid + alcohol (reverse); alkali gives the salt.
Esters of glycerol and fatty acids.
Fat/oil + NaOH → glycerol + soap.
Hydrophobic tail, hydrophilic –COO⁻ head.
Soap forms scum; detergents do not.
Soaps biodegradable; branched detergents were not.
3 quick games on this lesson. Earn XP and badges as you play — your best score for each game is saved. Games are for practice and do not change your exam readiness. More games in the Chemistry Arcade.
8 items modelled on real CSEC Paper 1 questions. Choose one answer for each, then check. Aim for 80% or better. Work each item on paper first.
Write full answers, then reveal the mark scheme and tick the points you earned (16 marks in total). Show all your working — method marks count. Your answers are saved on this device.
Question 1 [16 marks]
Ethyl ethanoate is prepared from ethanol and ethanoic acid.
(a) (a) Write an equation for the formation of ethyl ethanoate and state the type of reaction. [3]
(b) (b) State the catalyst and a condition for the reaction. [2]
(c) (c) State two properties of esters. [2]
(d) (d) Describe how ethyl ethanoate is hydrolysed using sodium hydroxide. [3]
(e) (e) Describe how soap is made from a fat or oil. [3]
(f) (f) Compare soap and soapless detergents in hard water and in terms of biodegradability. [3]
Find these in your own past-paper booklets for extra timed practice. Items above are written in the style of these papers; any adapted from a specific question say so.