C7 - Organic Chemistry Flashcards Preview

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Flashcards in C7 - Organic Chemistry Deck (24)
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1
Q

What is the formula for an alkane?

A

C n H 2 n+2

2
Q

What does ‘saturated’ mean for alkanes?

A

It consists of only single bonds. C-C.

3
Q

Describe a homologous series.

A

Organic compounds that react in a similar way.

4
Q

Name the first 4 alkanes.

A
  1. Methane
  2. Ethane
  3. Propane
  4. Butane
5
Q

Why does viscosity change for each hydrocarbon?

A

The shorter it is, the less viscous (gloopy) it is.

6
Q

What length hydrocarbons are more volatile?

A

Shorter hydrocarbons are more volatile.

7
Q

Why does the flammability change for each hydrocarbon?

A

The shorter it is, the more flammable (easy to ignite) it is.

8
Q

When will complete combustion happen?

A

When there is enough oxygen

9
Q

Give the word equation for incomplete combustion.

A

hydrocarbon + oxygen → carbon dioxide + water (+ energy)

10
Q

What happens to hydrocarbons during complete combustion?

A

They oxidise.

11
Q

Why are hydrocarbons useful as fuels?

A

Because of the amount of energy they produce during complete combustion.

12
Q

How was crude oil formed?

A

Dead plants and animals (mainly plankton) became trapped in mud under a high temperature and pressure.

13
Q

Give 1 problem with Crude Oil.

A

It is a finite resource, non-renewable.

14
Q

What is crude oil?

A

A mixture of lots of different hydrocarbons.

15
Q

What is the first step of Fractional Distillation?

A

Crude oil is heated to around 450 degrees so it vaporises.

16
Q

What happens in fractional distillation after crude oil has been heated?

A

The gas enters a fractionating column, where there is a temperature gradient.

17
Q

How does the crude oil separate once in a column?

A

Long hydrocarbons have a high boiling point so cool and condense into liquids near the bottom of the column.

Opposite for short hydrocarbons.

18
Q

Give 2 uses of crude oil.

A
  1. Fuel

2. Petrochemical industry (e.g. for polymers, solvents, lubricants)

19
Q

What is the goal of fractional distillation?

A

To separate crude oil into fractions.

20
Q

What is the goal of cracking?

A

To produce shorter, more useful alkanes and alkenes from longer hydrocarbons.

21
Q

How do you test for alkenes?

A

Put in bromine water and shake. If the orange bromine water becomes decolourised, an alkene is present.

22
Q

What type of reaction is cracking?

A

Thermal decomposition.

23
Q

Describe catalytic cracking in 3 steps.

A
  1. Vaporise
  2. Pass over hot powdered aluminium oxide catalyst.
  3. Long-chain splits on surface of specks of catalyst.
24
Q

Describe steam cracking in 3 steps.

A
  1. Vaporise
  2. Mix with steam
  3. Heat to a higher temp