Chapter 18.3: Alcohols and Carboxylic Acids

Alcohols

alcohols are a homologous series of organic compounds which contain the hydroxyl functional group

Functional group of alcohol

hydroxyl group or —OH

alcohols are ________ liquids at room temperature and pressure

volatile

solubility of alcohols in water

they are soluble in water

• but their solubility decreases and boiling point increases as their molecular size increase

why does the solubility of alcohols decrease

this is due to the forces of attraction increasing between the alcohol molecules

acidity of alcohols

they are neutral

alcohol + oxygen

carbon dioxide + water vapour

how can alcohol be oxidised to carboxylic acids

heat the alcohol with an oxidising agent like acidified potassium manganate (VII)

alcohol + oxygen from oxidising agent

carboxylic acid + water

how is ethanol manufactured

by the fermentation of carbohydrates

fermentation

a chemical process in which microorganisms such as yeast act on carbohydrates in the absence of oxygen to produce ethanol and carbon dioxide

equation for fermentation of carbohydrates

C6H12O6 —> 2 C2H5OH + 2 CO2

whats this setup for

the preparation of ethanol in the laboratory

purpose of limewater in prep of ethanol setup

to ensure that carbon dioxide was produced and that fermentation was taking place.

also to act as an airlock

how is ethanol extracted from the solution of carbon dioxide and a dilute solution of ethanol

fractional distillation

what happens when ethanol is exposed to oxygen

ethanol would be oxidised to ethanoic acid by bacteria in the air.

word equation for:

ethanol would be oxidised to ethanoic acid by bacteria in the air.

ethanol + oxygen from air —> ethanoic acid + water

how is the set up for fermentation of carbohydrates made air-tight

• the rubber bung is secured tightly to the flask

• limewater in the test tube prevent oxygen from entering the apparatus

functional group of carboxylic acids

carboxyl group -COOH

general formula for carboxylic acids

CnH2n+1COOH

carboxylic acids solubility in water

they are soluble

why are carboxylic acids weak acids

they ionise partially in water, therefore the concentration of H+ ions is low

carboxylic acids + reactive metal

salt + hydrogen

ethanoic acid + magnesium

magnesium ethanoate + hydrogen

carboxylic acid + carbonate

salt + carbon dioxide + water

carboxylic acid + base

salt + water

ethanoic acid + copper(II) oxide

copper(II) ethanoate + water

how can ethanoic acid be produced

oxidation with acidified potassium manganate(VII) or by atmospheric oxygen