Download Intermediate 1 Unit 2 Homework 5

Intermediate 1
Unit 2
Homework 1
Metals
Some metals are found uncombined in the Earth’s crust. E.g. Gold, silver and copper.
Most metals however are found combined with other elements. Some metals are
extracted from their ore, by heating with carbon e.g. iron. Some metals are extracted
from their ores by using electricity. E.g. aluminium.
An alloy is a mixture of metals or of metals with non-metals. Some important alloys
are brass, solder and stainless steel.
When a metal reacts with oxygen, a metal oxide is produced.
E.g. zinc + oxygen
--------------- Zinc oxide
Some metals react with oxygen to produce hydrogen gas. Some metals react with acid
to produce hydrogen gas.
The test for hydrogen is that it burns with a pop.
Questions
1. Name one metal found uncombined in the Earth’s crust.
(1mark)
2. Name a very important metal extracted from its ore by heating with carbon
(1mark)
3. How is aluminium extracted from its ore?
(1mark)
4. What is an alloy? Name one. Give a use for it
(3marks)
5.What is produced when a metal reacts with oxygen?
(1mark)
6. What gas is produced when some metals react with water?
(1mark)
7. What gas is produced when some metals react with acid?
(1mark)
8. What is the test for hydrogen gas?
(1mark)
Intermediate 1
Unit 2
Homework 2
Corrosion
Corrosion is a chemical reaction which involves the surface of a metal changing from
an element to a compound. Rusting is the corrosion of iron
Both oxygen (from the air) and water are required for rusting. Rust indicator can be
used to show how much rust has taken place. Acid rain and salt can speed up rusting.
Painting, greasing, electroplating, galvanising, tin- plating or coating with plastic can
keep out air and water.
If zinc (galvanising) or magnesium is attached to iron, it stops it from rusting.
Electricity comes from a chemical reaction in a battery. When the chemicals run out
the battery must be replaced. Different pairs of metals in a battery produce a different
voltage. It is the reactivity of the metals, which decides the size of the voltage in a
battery.
Questions
1.Rusting is the corrosion of what metal?
(1mark)
2. What two substances are required for rusting?
(2marks)
3.What do we call the substance which shows how much rusting has taken place?
(1mark)
4.Name 2 substances that speed up rusting?
(2marks)
5. Name 2 ways to stop air and moisture from getting to the surface of a metal
(2marks)
6.Name 2 metals that can be attached to iron to stop it from rusting?
(2marks)
7. Where does the electricity come from in a battery?
(1mark)
8. Why to batteries have to be replaces?
(1mark)
9.What happens to the voltage if two different pairs of metals are used?
(1mark)
10. What decides the size of the voltage in a battery?
(1mark)
Intermediate 1
Unit 2
Homework 3
Personal needs
When cleaning things the main problem is oil and grease because they don’t dissolve
in water alone. Cleaning chemicals are required and work by breaking the oil and
grease into smaller droplets when mixed with water.
Some soaps form a scum with hard water. Soapless detergents are used to form lather
with hard water.
Clothing fabrics are made form thin strands called fibres. Natural fibres come from
plants and animals. Synthetic fibres come from the chemical industry. Fibres are made
of long chain molecules called polymers. Dyes are coloured compounds which are
used to give bright colours to clothing
A fuel is a chemical which is burned to produce energy. Combustion is another word
for burning. A fire needs a fuel, Oxygen (from the air) and a high temperature to start
and keep a fire going.
Questions
1. When cleaning something why do oil and grease cause the most problems?
2. What do cleaning chemicals do to the oil and grease?
3. What kind of water will cause a scum to form with soap?
4. Where do natural fibres come from?
5. What are synthetic fibres?
6. What are the long chain molecules in fibres called?
7. What is a fuel?
8. Name three things to keep a fire going?
Intermediate 1
Unit 2
Homework 4
Fuels
Fossil fuels are made from animal and plant remains over a very long period of time.
They are finite resources i.e. they cannot be replaced. Over-use of fossil fuels may
lead to a fuel crisis. The compounds, which are found in fossil fuels, are mainly
hydrocarbons.
A hydrocarbon is a compound which contains hydrogen and carbon only.
Hydrocarbons burn in a plentiful supply of air to produce carbon dioxide and water.
Renewable sources of energy are ones which can be replaced. Three examples are:
methane, ethanol and hydrogen. Ethanol comes from sugar, methane from biogas and
hydrogen from water.
Crude oil is a mixture of hydrocarbons. It is separated into fractions by fractional
distillation. A fraction is a group of hydrocarbons with boiling points within a given
range. Cracking is an industrial method for producing a mixture of smaller, more
useful molecules.
Questions
1. Why must we not over-use fossil fuels?
2. What is a hydrocarbon?
3.
4.
(1)
(2)
What two substances are formed when a hydrocarbon burns in a plentiful
supply of air?
(2)
What do we mean by renewable sources of energy?
(1)
5. Name one renewable source of energy and write down where it comes from?
(1)
6.
What do we mean by a fraction of crude oil?
(1)
7. What do we call the process of splitting crude oil into different fractions?
(1)
8.
What is cracking?
(1)
Intermediate 1
Homework 5
Plastics
Unit 2
Plastics are synthetic materials i.e. made by the chemical industry. Most plastic are
made form oil. Some examples of plastics are polythene, polystyrene, Perspex, PVC,
nylon, Kevlar, Bakelite, Formica, silicones.
Thermoplastics soften when heated. Thermosetting plastics do not soften when
heating. Some thermoplastics are nylon and terylene.
Some thermosetting plastics are Ilrea formaldehyde, melamine formaldehyde and
polyurethane.
Questions
1. Plastics are described as synthetic materials. What does this mean?
2. What are most plastics made from?
3. Give 4 examples of plastics
4. What are thermoplastics?
5. What are thermosetting plastics?
6. Give 2 examples of thermoplastics
7. Give 2 examples of thermosetting plastics
Intermediate 1
UNIT 2
HOMEWORK 6
Plastics2
Biodegradable materials are broken down by bacteria in the soil and rot away. Most
plastics are not biodegradable and their durability and lightness can cause
environmental problems.
Some plastics can burn or smoulder to give off toxic fumes, including carbon
monoxide. Options for disposing of plastics include: incineration, recycling and
burying. Recycling can be difficult because of the many different kinds of plastics in
common use.
Plastic are made up of polymers. Polymers are made form many small molecules
called monomers. The process of making a monomer by joining many monomers
together is called polymerisation. Polythene is made form ethane monomers.
Questions
1. What do we mean by biodegradable materials?
2. Why can non-biodegradable plastics cause problems?
3. Name 1 of the toxic fumes given off when some plastics burn or smoulder
4. Why should we try to recycle plastics?
5. Why can the recycling of plastics sometimes be difficult?
6. What are polymers?
7. Name the monomer from which polyethene is made