Difficult stuff (10/10/26)

Give a use of refinery gases

Heating

Give a use of gasoline

Car fuel

Give a use of kerosene

Aircraft fuel

Give a use of diesel

Lorry fuel

Give a use of fuel oil

Ship fuel

Give a use of bitumen

Road surfacing

Give the word equation for complete combustion of a hydrocarbon

hydrocarbon + oxygen → carbon dioxide + water

Give two word equations for incomplete combustion of a hydrocarbon

hydrocarbon + oxygen → carbon + water

hydrocarbon + oxygen → carbon monoxide + water

How is nitrous oxide formed?

Give a symbol equation

Temperatures in car engines are high enough for the nitrogen and oxygen to react to form nitrogen oxides.

N₂ + O₂ → 2NO

Explain how the combustion of a common impurity in fuels can lead to environmental problems.

• Sulfur in fuels is combusted to form sulphur dioxide

• Sulphur dioxide dissolves in water vapour to form sulphuric acid

• This causes acid rain

What is cracking?

The process of breaking down longer-chain alkanes into shorter-chain alkanes and an alkene

Why is cracking important?

• The shorter-chain alkanes are more useful (eg. for fuel in cars/planes)

• The alkenes can be used to make polymers

• More profit for oil companies

Give two possible catalysts for cracking

What is the temperature necessary?

Silica or alumina

600-700 degrees Celsius

Which group are the halogens?

Describe the reaction between alkanes and halogens?

What condition is necessary?

17

Substitution reaction: A hydrogen atom in the alkane is replaced by a halogen atom

UV light

Do alkanes react with bromine under normal conditions?

Why/why not?

If so, what is the name of the molecule formed?

No

Without UV it is an addition reaction, and they do not have a double bond to break.

N/A

Do alkenes react with bromine under normal conditions?

Why/why not?

If so, what is the name of the molecule formed?

Yes

Without UV it is an addition reaction, so the double bond breaks to bond with 2 bromine atoms

A dibromoalkene

How do you distinguish between an alkane and an alkene?

Add bromine water

If it decolourises (orange to colourless), it is an alkene

If it remains orange, it is an alkane

Give three problems associated with polymers

• They are inert and therefore non-biodegradable

• They release toxic fumes when burned

• They are made from crude oil which is a non-renewable source

Give three methods of oxidizing ethanol

1. Complete combustion with oxygen

2. Microbial oxidation

3. Chemical oxidation

Give the word equation for complete combustion of ethanol

Give the symbol equation for complete combustion of ethanol

Ethanol + Oxygen → Carbon dioxide + Water

C₂H₅OH + 3O₂ + 2CO₂ + 3H₂O

What is the product of microbial oxidation of ethanol?

Draw the displayed formula

Ethanoic Acid

What two things are needed for microbial oxidization of ethanol?

• Oxygen

• Bacteria

What is one use of microbial oxidization of ethanol?

Making vinegar (a solution of ethanoic acid)

What is the oxidizing agent called for chemical oxidation of ethanol?

Potassium dichromate (VI)

Write a word equation for the chemical oxidation of ethanol

Ethanol + potassium dichromate (VI) → Ethanoic acid + Water

What condition is needed for chemical oxidation of ethanol?

Heating

What is the catalyst for chemical oxidation of ethanol?

Dilute sulphuric acid

What is the colour change for chemical oxidation of ethanol?

Orange to green

Give two methods for production of ethanol

Catalytic Hydration (using steam)

Fermentation

Give the word equation for catalytic hydration

Ethene + Water → Ethanol

Give the four conditions necessary for catalytic hydration

Steam

300°C

60-70 atm.

Phosphoric Acid catalyst

Give the word equation for fermentation

Glucose → Ethanol + Carbon Dioxide

What three conditions are necessary for fermentation to occur

• Yeast must be present

• 30°C

• No oxygen (anaerobic)

Draw the carboxylic acid functional group

COOH