Organic Chem Flashcards
Alkanes a group of saturated hydrocarbons. What does this mean?
They are compounds/ molecules that are made up of only carbon and hydrogen and they only contain single bonds.
What is the general formula of the Alkanes?
C n H 2n+2
What helps you remeber the first 4 Alkanes and Alkenes?
Monkeys- Meth ane/ ene (1 carbon)
Eat- Eth ane/ ene (2 carbons)
Peanut- Prop ane/ ene (3 carbons)
Butter- But ane/ ene (4 carbons)
Also- Pentane (5 carbons)
What does structural and displayed refer to?
Structural- the Molecular Formula
Displayed- the Displayed Formula
What reaction do hydrocarbons undergo when in the presence of air?
Combustion reactions
What is the difference between a complete combustion reaction and
an incomplete combustion reaction?
Complete Combustion:
Alkane + plenty of Oxygen —> Carbon Dioxide + Water
Incomplete Combustion:
Alkane + poor supply of Oxygen —> Carbon Monoxide + Water
How does the number of carbon atoms in a hydrocarbon affect the b.p / m.p?
+ explain
• More carbon atoms means that there are longer carbon chain lengths
• This creates more surface contact and therefore there is more intermolecular forces
• More energy is required to overcome these forces which results in a higher b.p / m.p
What is the general formula of the Alkenes?
C n H 2n
Alkenes are unsaturated. What does this mean?
They contain at least 1 double bond.
1) How many bonds can one Carbon atom have?
2) How many bonds does a double bond take up?
1) 4
2) 2 bonds
One way that you can test for Alkanes or Alkenes is by using bromine water (Br2)
How do you know which is which?
- Bromine water is orange.
- When it is mixed with an Alkane it stays orange.
- When it is mixed with an Alkene it starts off orange but it turns colourless.
Another way to test for Alkenes/ Alkanes is through combustion.
How can you tell which is which?
- Alkenes are more likely to undergo incomplete combustion.
- When you burn the substance, it will burn with a smoky flame which indicated that the substance is an Alkene.
- Alkanes however don’t burn with a smoky flame.
What is Cracking and why is it used?
- Cracking is used because there is a higher demand for smaller chain hydrocarbons because they can be used for fuels etc.
- Cracking is the process of breaking down long chain hydrocarbons into more useful, short chain hydrocarbons.
What does the process of Cracking entail?
- Using thermal decomposition of a long chain Alkane
- Aluminium oxide is used as a catalyst
- As a result you will get a shorter chain Alkane and an Alkene
What is the general formula for Alcohols?
C n H 2n+1 OH
How do you name an Alcohol?
The prefix is dependant on the number of carbons
And the suffix is: anol
E.g. name the alcohol with 3 carbons
3 carbons- Prop
Alcohol: Propanol
What is the general formula for a Carboxylic Acid?
C n H 2n+1 COOH
Carboxylic Acids are weak acids.
What does this mean?
A weak acid means that they partially ionise in aqueous solutions
1) How do Carboxylic Acids form?
2) What is the word equation for this?
1) Carboxylic acids form when an alcohol is oxidised
2) Alcohol + Oxygen —> Carboxylic Acid + Water
Just like in neutralisation reactions, Carboxylic Acids make salts.
How do you name these salts?
You name them by using the suffix as: oate
And the prefix comes from the Carboxylic Acid used. The base reacted becomes the first word in the salt.
E.g. Mathanoic acid + Calcium carbonate —> Calcium mathanoate + Water + Carbon dioxide
What is the word equation for making esters?
Carboxylic acid + Alcohol ⇌ Ester + Water
How do you name an Ester?
First part comes from the alcohol (with suffix ly)
Second part comes from the acid
E.g. Propanol + Ethanoic acid —> Proplyl ethanoate + Water
