Unit 2 - Topic 3 - Carboxylic Acids Flashcards
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)
Describe the reaction of carboxylic acids with carbonates and hydrocarbonates
Metal Carbonate + Acid –> Salt + Water + Carbon Dioxide
In both of these cases, a salt is formed together with carbon dioxide and water
You end up with a colourless solution.
Describe the reaction of carboxylic acids with salts of carboxylic acids
Carboxylic acids are acidic because of the hydrogen in the -COOH group. When the acids form salts, this is lost and replaced by a metal.
Give the uses of methanoic acid
In ant stings
A preservative and antibacterial agent in feedstock
Give the uses of ethanoic acid
Food flavouring - vinegar
A food preservative - pickling
Give the uses of butanoic acid
In butter, milk and cheese
Has a cheesy smell
Give the formula of lactic acid
CH_3CHOHCOOH
Give the uses of lactic acid
In sour milk, yogurt, and cheese
Forms in our muscles during exercise
What is the addition reaction called when you add water?
Hydration Reaction
What is the addition reaction called when you add Hydrogen?
Hydrogenation Reaction
What is the addition reaction called when you add any of the Halogens?
Halogenation Reaction
What is the addition reaction called when you add Bromine?
Bromination Reaction
What is the addition reaction called when you add Iodine
Iodination Reaction
Describe the boiling/melting points of carboxylic acids
As the molecule gets larger, the number of carbons increase which means there are greater intermolecular forces of attraction between molecules. This means much more energy is needed to separate it resulting in a greater melting/boiling point.
What is the functional group for carboxylic acids called?
Carboxyl Group
What will happen if the hydroxyl group is not at the end of a carbon chain?
It will not form a carboxyl group during mild oxidation
What will happen if the hydroxyl group is at the end of a carbon chain?
It will form a Carboxyl group during mild oxidation
