9F Flashcards
What do physical changes not create?
New substances
Are physical changes easy or difficult to reverse?
Easy to reverse
What do chemical reactions always produce?
One or more new substances
Are chemical reactions usually easy or difficult to reverse?
Difficult to reverse
What happens to the properties of substances in a chemical reaction?
They change
Give examples of physical changes
- Melting
- Boiling
- Condensing
- Freezing
Give examples of chemical reactions
- Combustion
- Neutralisation
- Thermal decomposition
What causes gas pressure?
The force of particles hitting the walls of the container
What happens to gas pressure when temperature increases?
It increases
What effect does increasing the number of particles in a container have on gas pressure?
It increases the pressure
How does decreasing the volume of a container affect gas pressure?
It increases the pressure
What is the reactivity series?
A list of metals in order of reactivity
What do metals that react with water produce?
Metal hydroxide and hydrogen
What do metals that react with dilute acids produce?
A salt and hydrogen
What do most metals form when they react with oxygen?
Metal oxides
What is a key requirement for iron and steel to rust?
Air and water
What accelerates the rusting of iron?
Salt
Name two methods to prevent rusting
- Physical barrier
- Sacrificial protection
What is stainless steel made of?
Iron and chromium
What do hydrocarbons contain?
Hydrogen and carbon only
What do hydrocarbons burn to produce?
Carbon dioxide and water
What is needed to start the combustion reaction of hydrocarbons?
An input of energy from a flame or spark
What type of reactions transfer energy from the reactants to the surroundings?
Exothermic reactions
What type of reactions use energy from the surroundings?
Endothermic reactions
