C2 - Changing State Flashcards
What do physical changes do to particles?
It changes their arrangement or their energy but does not change the particles itself
What happens when a solid is heated?
Its particles gain more energy,making the particles vibrate more which weakens the forces that holds the solid together
What is it called when a solid turns into a liquid
Melting
Why does a solid turn into a liquid?
As at a certain temperature when heated,called the melting point,the particles have enough energy to break free from their positions
What happens what a liquid is heated?
The particles get even more energy.This energy makes the particles move faster,which weakens and breaks the bonds holding the liquid together
What is it called when a liquid becomes a gas?
Boiling ( or evaporating )
Why does a liquid become a gas?
At a certain termperature,called the boiling point,the particles have enough energy to break their bonds
What happens when a gas cools (loses temperature) ?
The particles no longer have enough energy to overcome the forces of attraction between them. This leads to bonds forming between the particles
What is it called when a gas becomes a liquid?
Condensing
Why does a gas become a liquid?
As the substance has reached its boiling point,so many bonds have formed between the gas particles that the gas becomes a liquid
What happens when a liquid cools ( loses temperature ) ?
The particles have less energy,so they move around less. Additionally, there is not enough energy to overcome the attraction between the particles, so more bonds form between them.
What happens when a liquid meets its melting point?
The liquid then becomes a solid. This is called freezing
Why does a liquid become a solid?
At the liquids melting point, so many bonds have formed between the particles that they are held in place to become a solid
NOTE : ( ABOUT PREDICTING THE STATE OF A SUBSTANCE )
You might be asked to predict what state a substance is in at a certain temperature. If the temperature’s below the melting point of substance, It’ll be a solid. If it’s above the boiling point. it’ll be a gas. If it’s between the two points, then its a liquid.
Which of the molecular substances in the table is a liquid at room temperature (25 °C)?
Oxygen
Bromine
Nitrogen
Oxygen and nitrogen have boiling points below 25 °C, so will both be gases at room temperature. So the answer’s bromine. It melts at -7 °C and boils at 59 °C. So, it’ll be a liquid at room temperature
