Unit 2 - Topic 3 - Carboxylic Acids
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Describe vinegar
Vinegar is a dilute solution of ETHANOIC ACID. Its old name is ACETIC ACID. Vinegar is used in household cleaning products and is a non-toxic acid so can be used safely in household situations.
What are the -COOH group of atoms called?
Carboxylic group This is called the functional group as it gives the molecule the chemical properties of a CARBOXYLIC ACID.
Describe carboxylic acids
The carboxylic acids with a structure based on an alkane structure are called ALKANOIC ACIDS.
What does the name of the ethanoic acid tell you?
How many carbon atoms it contains That is has a single carbon to carbon bond oic means that it contains a carboxyl group (-COOH) The carboxyl group gives the molecule acidic properties
Name the family of carboxylic acids
Alkanoic acids
Describe the appearance (colour and state) of ethanoic acid
Colourless Liquid
Describe the smell of ethanoic acid
Strong and Sharp
Describe the conductivity of a solution of ethanoic acid
Insulator
Describe the solubility in water of the alkanoic acids
Methanoic, ethanoic, propanoic, and butanoic acid are all miscible in water, thereafter the solubility decreases as the size increases
Describe the pH (acidic, neutral, or alkaline) of ethanoic acid
Acidic
Describe the reaction with magnesium of ethanoic acid
Reacts slowly making H2O
Describe the reaction with marble (calcium carbonate) of ethanoic acid
Reacts slowly producing CO2
Describe ethanoic acid
A solution of ethanoic acid contains ions. With a pH less than 7, the solution contains the hydrogen ion (H+ ). A solution of ethanoic acid reacts with magnesium and calcium carbonate showing it is a typical acid.
How is etanoic acid formed?
Ethanoic acid is formed when ethanol undergoes mild oxidation. This reaction can happen in alcoholic drinks (e.g. wine or cider) when the ethanol reacts with oxygen from the air.
Describe how alkanoic acids are made
Alkanoic acids are made when alcohols undergo a mild oxidation reaction. The hydroxyl group (-OH) on the alcohol molecule has to be on the end of a carbon chain to produce a carboxyl group (-COOH) during mild oxidation.
What is the general formula of the alkanoic acids based on?
The alkane general formula
What is the general formula of the alkanoic acids?
CnH2n+1COOH The n in the formula is not related to the carbon atoms indicated by the name, as there is a carbon atom in the carboxyl group
Give the formula of methanoic acid
HCOOH
Give the formula of ethanoic acid
CH_3COOH
Give the formula of propanoic acid
C_2H_5COOH
Give the formula of butanoic acid
C_3H_7COOH
Describe the physical properties of the alkanoic acids
As the number of carbon atoms in the alkanoic acid molecule increases, the boiling point increases. As alkanoic acids increase in size their melting and boiling points increase due to the increasing strength of the intermolecular forces of attraction between molecules. The alkanoic acids have similar chemical properties and have a general formula showing they are a HOMOLOGOUS SERIES.
Describe the reaction of carboxylic acids with metals
Metal + Acid –> Salt + Hydrogen Carboxylic acids react with the more reactive metals to produce a salt and hydrogen. The reactions are just the same as with acids like hydrochloric acid, except they tend to be rather slower.
Describe the reaction of carboxylic acids with metal hydroxides
Metal Hydroxide + Acid –> Salt + Water These are simple neutralisation reactions and are just the same as any other reaction in which hydrogen ions from an acid react with hydroxide ions. They are most quickly and easily represented by the equation: H+ (aq) + OH- (aq) –> H2O (l)