C3.6 Alcohols, Carboxylic Acids and Esters Flashcards
What are alcohols?
A group of compounds that all contain an -OH group
What is the -OH group in alcohols an example of?
A functional group
What is a functional group?
A group of atoms responsible for the chemical properties of a compound
The alcohols are an example of a homologous series, what is a homologous series?
A group of chemicals that react in a similar way because they have the same functional group
What is the general formula for an alcohol?
CₙH₂ₙ₊₁ –> n = the number of carbons
What rule is applied to the name of alcohols?
They all end in ‘-ol’
What are the first 3 alcohols in the homologous series ?
Methanol, ethanol and propanol
Do alcohols contain double bonds?
No
How can you identify if a compound is an alcohol? (2)
Look for the ‘-OH’ group or see if it’s name ends in ‘-ol’
Are alcohols flammable?
Yes, they burn in air to produce carbon dioxide and water
Do the first three alcohols dissolve in water?
Yes, they all dissolve completely to form neutral solutions
How do alcohols react with sodium?
They react to give hydrogen and alkoxides
What are the three main uses of alcohols?
Alcoholic drinks, solvents, and fuel
What is the most commonly used alcohol in alcoholic drinks?
Ethanol, when consumed it causes damage to the liver and brain
What solvents are alcohols used in?
Ethanol is used in perfumes and after shave lotions, and ethanol is used to make methylated spirit which cleans paint brushes
Why is methylated spirit dyed a purply-blue colour?
Because it is poisonous to drink
What are the benefits of using ethanol as a fuel? (4)
It burns fairly cleanly, it’s non-smelly, it comes from a renewable source, and third world countries can grow loads of sugar cane which is fermented to make ethanol
What are carboxylic acids functional group?
-COOH
How is a carboxylic acid bonded to the functional group?
A double bond connects the carbon with a lone oxygen, and a single bond connects the carbon with the oxygen + hydrogen
What is rule which applies to the name of carboxylic acids?
They all end in ‘-anoic acid’
What are the first 3 carboxylic acids?
Methanoic acid, ethanoic acid, and porpanoic acid
How can you tell if a compound is a carboxylic acid? (2)
If its name ends in ‘-anoic acid’ or if it contains the functional group ‘-COOH’
What is produced when you react a carboxylic acid with a carbonate? (3)
Carbon dioxide, water and a salt ending in ‘-anoate’
Why is it when acids dissolve in water, an acidic solution is made?
Because the acids ionise and release H+ ions which are what make the solution acidic
what determines whether an acid is a strong or weak acid?
How well they ionise in water
What happens when you dissolve strong acids in water?
They ionise completely, all of the acid molecules will ionise and release H+ ions
What happens when you dissolve weak acids in water?
They only partially ionise, only some of the acid molecules ionise and release H+ ions
Are carboxylic acids an example of strong or weak acids?
Weak acids - they don’t ionise completely in water
What uses are there of carboxylic acids in industry? (3)
Soaps and detergents, vinegar and in the preparations of esters
How is ethanoic acid made?
By oxidising ethanol
How do you oxidise ethanol? (2)
By microbes (like yeast) causing the ethanol to ferment or with oxidising agents
What is the word equation for the oxidation of ethanol?
Ethanol + oxygen ==> ethanoic acid + water
How is vinegar made from ethanoic acid?
Ethanoic acid can be dissolved in water to make vinegar, which is used for flavouring and preserving food
What is the functional group of esters?
-COO-
How are esters bonded to their functional group?
By one double bond between the carbon and an oxygen, and one single bond between the carbon and the other oxygen
How are esters made?
From an alcohol and a carboxylic acid - an acid catalyst is usually used
What is the word equation for making an ester?
Alcohol + carboxylic acid ==> ester + water
What are the rules applied to the name of esters?
They all end in ‘-oate’, and the first part of the name comes from the alcohol that is used to make it and the second part comes from the carboxylic acid e.g. ethanol + ethanoic acid ==> ethyl ethanoate + water
How can you identify esters? (2)
Either by their functional group ‘-COO-‘ or if their name ends in ‘-oate’
What are the main properties of esters? (4)
They have a pleasant smell, they’re volatile, they are flammable and they don’t mix well with water, but do mix well with alcohols and other organic solvents
What are the uses of esters? (5)
Perfumes, flavourings, ointments, paint, glue and much more
What are the disadvantages of using esters? (3)
Inhaling the fumes of esters irritates mucous membranes in the nose and mouth, ester fumes are heavier than air and very flammable so when they come in contact with a naked flame they can cause a flash fire and some esters are toxic which is dangerous considering they are used as synthetic food additives
What benefits do esters have over other organic solvents? (2)
They aren’t as volatile or toxic, and they don’t release nearly as many toxic fumes as some of them - esters have begun to replace more toxic solvents that used to be used in paints and varnishes
