Simple Chemical Reactions – Test your understanding by filling in the missing
words.
Use the word bank to help you:
boiling
bubbles
gases
heat
corrosion
roofing
acid
colour
products
dissolves
rust
carbon
natural
new
carbon
energy
oxygen
condensation
reaction
lighted
element
reversed
magnesium
equation
word copper
metal
oxygen
copper
carbonate
limewater
dioxide
reactants
hydrogen
splint
baking
limestone
compound
metal
change
milky
flammable
petrol
reaction
chemical
dioxide
indigestion
pressure
fuel
gas
water
hazard
hydrogen
light
word
Exercise 1:
1. Hydrogen and carbon dioxide are ____________ . If they are formed in a reaction you will see
__________________ . This can be a sign that a chemical has happened.
2. Other signs of a chemical reaction might be an increase in temperature if __________________is released or
a change in____________________ .
3. Physical changes like ______________ do not make new materials and are easily __________________eg by
cooling, which causes __________________ .
4. The substances you start with are called _________________ , and after the chemical change, what is
formed are called the ___________________ .
5. Zinc consists of only one type of atom, so it is called an _____________________.
6. Carbon dioxide is made up of combining the different atoms carbon and oxygen, and is known as a
______________________.
7. A shorthand way of representing a chemical change is to use a ___________
__________ .
(13)
Exercise 2:
1. If a ______________reacts with acid the gas ________________ is usually formed.
2. The gas can be tested for by using a ____________ ______________ and the gas explodes with a pop!
3. The metal _________________ reacts fast with acids and completely ________________ in the acid. If all the
metal 'disappears' it must have formed a _______________ substance.
4. Acid attack on metals is an example of ___________________ , which can also be caused by the gas
____________________dissolved in water.
5. The metal ______________________does not readily react with acids and so can be used as a
___________________material because it will not ___________________ away like iron.
(12)
Exercise 3:
1. The 'fizz' in drinks is due to the 'escape' of the gas ____________ ______________ which is dissolved under
high _______________at the factory.
2. This gas can be tested for using ______________________ . If the gas is carbon dioxide, when bubbled
through this solution, it turns it ____________________ .
3. The gas carbon dioxide is formed when any acid reacts with any_________________ ________________
compound.
4. Rocks such as ___________________ fizz with acid and dissolve over thousands of years in acid rain to form
deep gorges.
5. Several substances in the home are also carbonates and 'fizz' with ______________________ . They include
__________________ powder and ____________________remedies.
6. When an acid reacts with something to form a gas, the fizzing is evidence of a _______________
__________________ .
(13)
Exercise 4:
1. This _________________ warning symbol means the substance is very _______________________ . A
substance like _____________________ should be labelled with this sign.
2a. When substances burn they react with the gas ___________________ and the reaction is fast releasing lots
of heat ________________ .
2b. The release of heat is a sign that a chemical _________________ is happening. Energy is often given out
as_____________ too in combustion reactions.
3a. Substances that give out heat _______________ on burning can be used as a _________________. Most
fuels contain the chemical elements ____________________ (C) and ________________________(H).
3b. Methane is fuel which we get from under the North Sea, and off the coast of Mossel Bay, and is also
known as ____________ ______________
4. Chemical reactions can be represented by _________________________equations, a sort of shorthand.
When the fuel methane burns in air, the word equation is ...
methane + oxygen ==> _______________
____________ + _________________
TOTAL = 55 marks
(17)
MEMO
Exercise 1
1. Hydrogen and carbon dioxide are gases. If they are formed in a reaction you will see bubbles.
This can be a sign that a chemical reaction has happened.
2. Other signs of a chemical reaction might be an increase in temperature if heat is released or a
change in colour.
3. Physical changes like boiling do not make new materials and are easily reversed eg by cooling,
which causes condensation.
4. The substances you start with are called reactants, and after the chemical change, what is
formed are called the products.
5. Zinc consists of only one type of atom, so it is called an element.
6. Carbon dioxide is made up of combining the different atoms carbon and oxygen, and is known
as a compound.
7. A shorthand way of representing a chemical change is to use a word equation.
Exercise 2
1. If a metal reacts with acid the gas hydrogen is usually formed.
2. The gas can be tested for by using a lighted splint and the gas explodes with a pop!
3. The metal magnesium reacts fast with acids and completely dissolves in the acid. If all the
metal 'disappears' it must have formed a new substance.
4. Acid attack on metals is an example of corrosion, which can also be caused by the gas
oxygen dissolved in water.
5. The metal copper does not readily react with acids and so can be used as a roofing material
because it will not rust away like iron.
Exercise 3:
1. The 'fizz' in drinks is due to the 'escape' of the gas carbon dioxide which is dissolved under high
pressure at the factory.
2. This gas can be tested for using limewater. If the gas is carbon dioxide, when bubbled through
this solution, it turns it milky.
3. The gas carbon dioxide is formed when any acid reacts with any metal carbonate compound.
4. Rocks such as limestone fizz with acid and dissolve over thousands of years in acid rain to form
deep gorges.
5. Several substances in the home are also carbonates and 'fizz' with acid. They include baking
powder and indigestion remedies.
6. When an acid reacts with something to form a gas, the fizzing is evidence of a chemical
change.
Exercise 4:
1. This hazard warning symbol means the substance is very flammable. A substance like petrol
should be labelled with this sign.
2a. When substances burn they react with the gas oxygen and the reaction is fast releasing lots of
heat energy.
2b. The release of heat is a sign that a chemical reaction is happening. Energy is often given out
as light too in combustion reactions.
3a. Substances that give out heat on burning can be used as a fuel. Most fuels contain the
chemical elements carbon (C) and hydrogen (H).
3b. Methane is fuel which we get from under the North Sea, and off the coast of Mossel Bay, and
is also known as natural gas.
4. Chemical reactions can be represented by word equations, a sort of shorthand. When the fuel
methane burns in air, the word equation is ...
methane + oxygen ==> carbon dioxide + water