C1

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C1 Carbon Chemistry

• Revision Lesson part one

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The Chemistry of Cooking
The process of cooking food causes some chemicals
to turn into others (i.e. a chemical change) and
these are irreversible. For example, consider a
protein molecule
Denatured
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Exam Questions

• Standard Demand
• 1.) Some foods need to be cooked. Explain why?
• (2 marks)
• 2.) Cooking food is an example of a chemical
  change. Finish the sentences to explain why.
  Choose the best words from the list.
• Energy irreversible reactant reversible
  substance
• The change is___________. An ___________ change
  takes place in the food. A new ________ is made.
• (3 marks)
• 3.) What happens to protein molecules when they
  are cooked?
• (1 mark)

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The Chemistry of Cooking
Now consider a potato cell
Cooking a potato causes the cell wall to break
and release starch grains making it
softer/easier to digest
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Baking Powder
Baking powder is used to make bread rise This is
a thermal decomposition reaction
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Testing for carbon dioxide - makes cakes/bread
rise
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Exam Questions

• Standard Demand
• 1.) Baking powder is a chemical called sodium
  hydrogencarbonate. When it is heated it
  decomposes to give sodium carbonate, carbon
  dioxide and water.
• a.) Write down the word equation for this
  reaction. (2 marks)
• b.) Write down the reactants of the reaction.
  (1 mark)
• c.) Write down the products of the reaction.
  (1 mark)
• 2.) The chemical test for carbon dioxide is to
  pass it through limewater. It will turn the
  limewater from _______ to _______. (2 marks)

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Exam Questions

• High Demand
• 1.) The formula for sodium hydrogencarbonate is
  NaHCO3. Write down the balanced symbol equation
  for this reaction. (3 marks)

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Food Additives
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Artificial Additives
Why do we use additives?
Some examples
Additive Why
Flavour enhancers Bring out taste and smell of food
Food colouring makes food look more appetising
Antioxidants Stops reaction with oxygen, preserves food
Emulsifiers Help oil and water mix in foods like salad cream and ice cream
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Emulsions
Whats an emulsion?
Its a mixture of oil and water, like in salad
dressing
Paint is an emulsion. Other examples
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Emulsifiers - the details
Water
Oil
-

Emulsifier
-
-
-
-

-
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Foundation 6 mark question

• The quality of written communication will be
  assessed in your answer to this question.
• Explain why cooking a meat is described as a
  chemical change.

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Level 3 Answer correctly applies knowledge of
how meat is a protein, description of how cooking
is a chemical change because it involves an
energy change that is irreversible. Understanding
of how proteins change shape-denatures. All
information in answer is relevant, clear,
organised and presented in a structured and
coherent format. Specialist terms are used
appropriately. Few, if any, errors in grammar,
punctuation and spelling. (56 marks) Level 2
Answer applies knowledge of how cooking meat is
a chemical change due to heating the food,
causing an energy change and irreversible
reaction. Specialist terms are used for the most
part appropriately. There are occasional errors
in grammar, punctuation and spelling. (34 marks)
Level 1 An incomplete answer, states cooking is
a chemical change because the reaction is
irreversible. Answer may be simplistic. There may
be limited use of specialist terms. Errors of
grammar, punctuation and spelling prevent
communication of the science. (12 marks) Level
0 Insufficient or irrelevant science. Answer not
worthy of credit. (0 marks)
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Higher - 6 mark question

• The quality of written communication will be
  assessed in your answer to this question.
• Explain how even though mayonnaise is made of
  oil, vinegar and egg yolk, it still makes a
  smooth substance.

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Level 3 Answer correctly applies knowledge of
how egg yolk has two part, one part is
hydrophobic and the other part is hydrophilic ,
description of how these two parts allow the oil
and water in mayonnaise to stay together .All
information in answer is relevant, clear,
organised and presented in a structured and
coherent format. Specialist terms are used
appropriately. Few, if any, errors in grammar,
punctuation and spelling. (56 marks) Level 2
Answer applies knowledge of how emulsifiers
work. For the most part the information is
relevant and presented in a structured and
coherent format. Specialist terms are used for
the most part appropriately. There are occasional
errors in grammar, punctuation and spelling. (34
marks) Level 1 An incomplete answer, states an
emulsifier description. Answer may be simplistic.
There may be limited use of specialist terms.
Errors of grammar, punctuation and spelling
prevent communication of the science. (12
marks) Level 0 Insufficient or irrelevant
science. Answer not worthy of credit. (0 marks)
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Smells
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Perfumes
Here are some facts about perfumes. Why are
these things important?

1. Perfumes are non-toxic
2. They are non-irritants
3. They evaporate easily
4. They do not dissolve in water
5. They dont react with water

A typical perfume reaction
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Solutions revision
If a substance CAN be dissolved it is called
__________ If a substance CANNOT be dissolved it
is called _________
Words soluble, solute, solvent, solution,
insoluble
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Higher - Making a solution

• A solution forms because there are
• Weak forces of attraction between solute
  molecules
• Strong forces of attraction between solute and
  solvent molecule

For example, nail varnish remover works because
the nail varnish remover molecules are attracted
to the nail varnish molecules with a stronger
attraction than water molecules are.
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Exam Questions

• Standard Demand
• 1.) To make a perfume alcohol is mixed with an
  acid to make an ester.
• a.) Write down a word equation for this reaction.
  
• b.) Write down the name of the ester that is made
  from ethanoic acid and butanol.
• 2.) Some people object to cosmetics being tested
  on animals. Explain why
• 3.) Some people say that cosmetics should be
  tested on animals. Explain why.
• 1. alcohol acid --------- ester water
• 2. Butyl ethanoate
• 3. Animals may be harmed, they have no control
  of what happens to them
• 4. Feel safer if cosmetics have been tested on
  animals, animals reaction would closely mimic
  ours

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Exam Questions

• High Demand
• 1.) If a liquid evaporates easily then the
  substance is volatile. Explain how this happens.
  Use ideas about forces between particles in your
  answer. (4 marks)
• 2.) Water does not dissolve nail varnish. Use
  ideas about the forces of attraction between
  molecules in your answer. (2 marks)
• 1. When a liquid is heated, particles will move
  faster, these will overcome the forces of
  attraction of other particles and escape, meaning
  the substance evaporates easily, it s volatile.
• 2. Molecules of nail varnish are strongly
  attracted to each other, and this attraction is
  stronger than the one between the water molecules
  and nail varnish

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Making crude oil useful
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Alkanes
Alkanes are SATURATED HYDROCARBONS. What does
this mean? HYDROCARBONS are molecules that are
made up of hydrogen and carbon atoms SATURATED
means that all of these atoms are held together
by single bonds, for example
Alkanes are fairly unreactive (but they do burn
well).
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Fuels
Fuels are substances that can be used to release
useful amounts of energy when they burn, e.g.
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Crude Oil
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Hydrocarbons and crude oil
Crude oil is a mixture of HYDROCARBONS (compounds
made up of carbon and hydrogen). Some examples

• Longer chains mean
• Less ability to flow
• Less flammable
• Less volatile
• Higher boiling point

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General Formulae for Alkanes
Instead of circles, lets use letters
General formula for alkanes CnH2n2
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Alkenes
Alkenes are different to alkanes they contain
DOUBLE COVALENT bonds. For example
This double bond means that alkenes have the
potential to join with other molecules this
make them REACTIVE.
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General Formulae for Alkenes
General formula for alkenes CnH2n
Higher Alkenes react with Bromine water Alkene
Bromine Water Colourless Solution
Br2
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Fractional distillation
Crude oil can be separated by fractional
distillation. The oil is evaporated and the
hydrocarbon chains of different lengths condense
at different temperatures
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Remember! Its the forces between the
molecules that are broken. The forces within the
molecules (covalent bonds) are not affected by
heating.
covalent bond cant break these!
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Forces between molecules
Weak intermolecular force of interaction here
Longer molecules stronger intermolecular force
of attraction
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Cracking
Shorter chain hydrocarbons are in greater demand
because they burn easier. They can be made from
long chain hydrocarbons by cracking
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Cracking
This is a THERMAL DECOMPOSITION reaction, with
clay used as a catalyst
INVOLVES HEAT AND A CATALYST Cracking can be used
(as well as fractional distillation) to extract
petrol from crude oil. Helps supply and
demand!!!!!!
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Exam Questions

• Standard Demand
• 1.) All the oils of crude oil are hydrocarbons.
  What is a hydrocarbon? (2 mark)
• 2.) Explain how damage is done to the environment
  if oil tankers are damaged. (2 marks)
• 3.) When a large alkane is cracked it becomes a
  smaller alkane and an alkene. Explain why an
  alkene is a different type of hydrocarbon to an
  alkane. (1 mark)
• 4.) What are alkenes useful for making? (1 mark)
• 1. Contains hydrogen and carbon only
• 2. harm animals, pollutes beaches and destroys
  unique habitats
• 3. Alkenes are unsaturated (double bond)
  therefore more reactive
• 4. Polymers (plastics)

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Foundation - 6 marker question

• The quality of written communication will be
  assessed in your answer to this question.
• 1.) A country produces 25 more than its demand
  of heavy oil from crude oil distillation.
  However, its supply of petrol from the
  distillation is only 68 of its need. Explain how
  they could solve this problem.

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Level 3 Answer correctly applies knowledge of
how alkanes like paraffin can be broken down into
more useful products such as petrol, by the
process of cracking. Detailed description of
cracking, including thermal decomposition
reaction, high temperature and use of a catalyst.
All information in answer is relevant, clear,
organised and presented in a structured and
coherent format. Specialist terms are used
appropriately. Few, if any, errors in grammar,
punctuation and spelling. (56 marks) Level 2
Answer applies knowledge of how cracking can be
used to deal with supply and demand. For the most
part the information is relevant and presented in
a structured and coherent format. Specialist
terms are used for the most part appropriately.
There are occasional errors in grammar,
punctuation and spelling. (34 marks) Level 1
An incomplete answer, states that cracking can
be used to supply petrol. Answer may be
simplistic. There may be limited use of
specialist terms. Errors of grammar, punctuation
and spelling prevent communication of the
science. (12 marks) Level 0 Insufficient or
irrelevant science. Answer not worthy of credit.
(0 marks)
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Higher - 6 marker question

• The quality of written communication will be
  assessed in your answer to this question.
• 1.) Explain why crude oil can be separated by
  fractional distillation. Use ideas about chain
  length, forces of attraction and boiling points
  in your answer. (6 marks)

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Level 3 Answer correctly applies knowledge of
how crude oil can be separated by fractional
distillation because molecules in different
fractions have different length chains. Long
chain molecules, such as bitumen have strong
forces of attraction between molecules, meaning
alot of energy is needed to break each molecule
away from another, so they have high boiling
points..All information in answer is relevant,
clear, organised and presented in a structured
and coherent format. Specialist terms are used
appropriately. Few, if any, errors in grammar,
punctuation and spelling. (56 marks) Level 2
Answer applies knowledge of how crude oil is
separated by fractional distillation, including
part of points but not all. For the most part the
information is relevant and presented in a
structured and coherent format. Specialist terms
are used for the most part appropriately. There
are occasional errors in grammar, punctuation and
spelling. (34 marks) Level 1 An incomplete
answer, states how fractional distillation works.
Answer may be simplistic. There may be limited
use of specialist terms. Errors of grammar,
punctuation and spelling prevent communication of
the science. (12 marks) Level 0 Insufficient
or irrelevant science. Answer not worthy of
credit. (0 marks)