Topic 2 - (reactions) Flashcards
What does the law of conservation of mass mean?
That mass is never lost or gained in chemical reactions
If the ………. is a gas, you will observe a mass increase
reactant
If the ………. is a gas, you will observe a mass decrease
Product
What is combustion?
When a fuel reacts with oxygen to release energy
What are 3 things needed to make a combustion?
- fuel
- heat
- oxygen
What is oxidation?
When a substance reacts and combines with oxygen
Combustion is a type of ………… reaction
Oxidation
What is the equation of rusting?
Iron + oxygen - iron oxide (rust)
What is iron oxide?
Rust
Exothermic reactions….
Release heat
Endothermic reactions….
Take in heat
Which reactions are exothermic?
Neutralisation and oxidation
Which reactions are more common? Exothermic or endothermic?
Exothermic
Which reactions are also endothermic reactions?
Thermal decomposition reactions
What is a thermal decomposition reaction?
A reaction that uses heat to break down a substance into smaller molecules
What is an example of a thermal decomposition reaction?
CaCO3 - CaO + CO2
Making lime from lime water!
What do carbonates produce when they decompose?
Carbon dioxide
Name 3 uses of thermal decomposition reactions
- Making lime from lime water
- Extracting Mercury
- Thermal cracking
What is a precipitation reaction?
A reaction in which a solid is made
What is the precipitate in a reaction?
The solid
What does the state symbol (aq) mean?
Dissolved into solution
What do reactions involve?
A transfer in energy
What is an example of a precipitation reaction? And what is the precipitate
Potassium iodide (aq) + lead nitrate (aq) - potassium nitrate (aq) + lead iodide (s)
Precipitate: LEAD IODIDE (s)
What is CaCO3?
Limestone
What is iron oxide? ( FeO)
Rust
In a chemical reaction, WHY is there no change in mass?
Because you can’t create or destroy atoms
What can oxidation reactions be used to make?
Acids and bases
What is an example of an endothermic reaction?
- Sodium hydrogen carbonate + hydrochloric acid
- photosynthesis
