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Module 7: Organic Chemistry
Quick questions on Esters, esterification and saponification explained: HSC Chemistry Module 7
8short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What are physical properties of esters?Show answer
Esters have a polar but no , so they cannot hydrogen-bond to each other. Boiling points are lower than the parent acid and alcohol of similar molar mass, comparable to ketones. Small esters are volatile liquids with characteristic fruity smells.
What is hydrolysis?Show answer
Acid hydrolysis. Reflux the ester with dilute sulfuric acid; the reverse of esterification:
What is purification?Show answer
Pour the cooled mixture into saturated sodium hydrogencarbonate to neutralise unreacted acid (effervescence stops when complete). Separate the organic layer, dry over anhydrous , then distil at the boiling point of the ester.
What is acid hydrolysis?Show answer
Reflux the ester with dilute sulfuric acid; the reverse of esterification:
What is base hydrolysis?Show answer
Reflux the ester with aqueous NaOH:
What is q1?Show answer
Name the ester formed when propan-1-ol reacts with ethanoic acid, and write the balanced equation including the catalyst. [3 marks]
What is q2?Show answer
A 9.20 g sample of ethanol is reacted with excess butanoic acid to form ethyl butanoate. If the percent yield is 60 percent, calculate the mass of ester produced. [3 marks]
What is q3?Show answer
Sodium hydroxide is used to hydrolyse ethyl ethanoate. (a) Write the balanced equation. (b) State why this reaction is described as saponification when applied to a triglyceride.