Page 136 - Knowledge Organiser Yr7 24-25

Knowledge Base: Science 7.8 Reactions Year 7
1. Chemical and Physical Changes
1.1
In a chemical reaction, what happens to the atoms?
They are rearranged
1.2
How could you tell if a chemical reaction has taken place?
Temperature change, colour change, gas formed, solid formed
4. Combustion
4.1
What gas must be present for burning to happen?
Oxygen
4.2
What is the scientific term for a chemical reaction where burning happens?
Combustion
4.3
Burning fuels is useful because it releases light and it causes which store of energy to increase?
Thermal store
4.4
What two things are produced when a fuel is burnt?
Carbon Dioxide and Water
4.5
Write the word equation for the combustion of methane
Methane + Oxygen Carbon Dioxide + Water
4.6
Balance the symbol equation for the combustion of methane and draw a particle diagram so show that no atoms have been lost or created during the reaction CH4 + O2CO2 + H2O
1.3 Give an example of a physical change Melting, Boiling, Condensing, Freezing
1.4
What is the difference between a physical and a chemical change?
A chemical change results in the formation of new products. A physical change no new chemicals are formed
2. Law of Conservation of Mass
2.1
What is the law of conservation of mass?
Atoms are neither created or destroyed during a reaction, they are simply rearranged
2.2
If mass appears to be lost in a reaction, what has happened?
A gas has been produced which escapes
2.3
If mass appears to be gained in a reaction, what has happened?
Atoms of a gas from the air have been added
2.4
If you react 7g of reactant A with
4 g of reactant B, what mass of product C will you have (A + BC)?
7g + 4g = 11g
5. Gas Tests
5.1
What is the test for carbon dioxide?
Turns limewater cloudy
5.2 What is the test for oxygen? Relights a glowing splint
5.3 What is the test for hydrogen? Makes a squeaky pop with a lit splint
3. Thermal Decomposition
3.1
When copper carbonate is heated, it forms copper oxide and carbon dioxide. What is the name of this type of reaction?
Thermal decomposition
3.2
Write the general word equation for a thermal decomposition reaction
Metal Carbonate
Metal Oxide + Carbon Dioxide
3.3
Write the word equation for the thermal decomposition of Calcium Carbonate
Calcium Carbonate Calcium Oxide + Carbon Dioxide
3.4
Draw a particle diagram to represent the thermal decomposition of calcium carbonate which shows
that no atoms have been created or destroyed during
the chemical reaction. Use the symbol equation to help you.
6. Temperature Changes
6.1
What is the name given to chemical reactions which cause an increase in the temperature of the surroundings?
Exothermic reactions
6.2
What is the name given to chemical reactions which cause a decrease in the temperature of the surroundings?
Endothermic reactions
6.3
Why do reactions cause a change in the temperature of the surroundings?
When the atoms rearrange energy may be absorbed or released
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