Yr 8- Revising chemical reactions

Yr 8- Revising chemical reactions

Combustion

• When fuels react with oxygen to release energy, it is a combustion reaction.

• Combustion reactions produce Carbon Dioxide and Water.

Multiple Choice

Fuels burn to transfer

• molecules

• atoms

• energy

• temperature

Multiple Choice

Combustion is another word for

• reaction

• oxidation

• decomposition

• burning

Multiple Choice

When a fuel burn it reacts with

• carbon dioxide

• oxygen

• water

• hydrogen

Combustion experiment

• Carbon dioxide and water is produced

• Water is condensed in the U tube

• This will turn cobalt chloride paper pink

• Carbon dioxide turns lime water milky

Multiple Choice

The cobalt chloride changes colour from

• pink to blue

• blue to pink

• colourless to milky

• milky to colourless

Multiple Choice

This is an example of -----------------

• combustion

• decomposition

• displacement

• oxidation

Thermal decomposition

• When a chemical substance breaks down (decomposes) due to heat into at least two chemical substances.

Multiple Choice

This is an example of ------------------------------

• combustion

• decomposition

• displacement

• oxidation

Thermal decomposition of carbonates

• Metals high up in the reactivity series - such as calcium - have carbonates that need a lot of energy to decompose them.

• Metals low down in the reactivity series - such as copper - have carbonates that are easily decomposed.

Multiple Choice

Aluminium carbonate decomposes easily than iron carbonate

• True

• False

• Difficult to say

Multiple Choice

At room temperature potassium carbonate decomposes into potassium oxide and carbon dioxide.

• True

• False

Multiple Choice

At room temperature copper carbonate decomposes into

• copper and carbon dioxide

• copper oxide and carbon oxide

• copper dioxide and carbon dioxide

• copper oxide and carbon dioxide

Multiple Choice

When copper carbonate CuCO₃ is decomposed, it breaks into

• Copper and carbon dioxide

• Copper oxide and carbon dioxide

• Copper oxide and carbon monoxide

• Copper dioxide and carbon

Multiple Choice

Strontium is more stable to thermal decomposition than Calcium

• False

• True

• Impossible to say

Multiple Choice

Calcium nitrate decomposes to form

• Calcium oxide, nitrogen oxide and nitrogen

• Calcium dioxide, nitrogen oxide and nitrogen

• Calcium oxide, nitrogen dioxide and oxygen

• Calcium dioxide, nitrogen dioxide and oxygen

Law of conservation of mass

• Mass is never gained or lost in a chemical reaction.

• When a reaction happens, the atoms in the chemicals are rearranged into different compounds. No new atoms are created and no atoms can disappear.

Multiple Choice

When 16 g of methane combines with 2 molecules of oxygen each weighing 32 g, we get 44 g of carbon dioxide and

• 1 molecule of 18 g of water

• 2 molecules of 18 g of water

• 1 molecule of 18 g carbon dioxide

• 2 molucules of 18 g of carbon dioxide