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P6 - Molecules and matter - Coggle Diagram
P6 - Molecules and matter
6.1 - Density
Rearranging the density equation - m=p x V ~ V = m/p
Objects that have a lower density than water float in water.
To measure the density of a solid object or a liquid, measure its mass and its volume, then use density equation - p=m/v
Density of a substance
m - mass - kg
V - volume - cubic meters - m3
p - density - kg per cubic meter - kg/m3
Density = mass/volume
6.5 - Specific latent heat
Latent heat
E - energy - J
m - mass - kg
Lf - specific latent heat of fusion - J/kg
E = m x L
Specific latent heat of fusion is the energy needed to melt 1kg of a substance without changing its temperature.
The specific latent heat of ice can be measured using a low-voltage heater to melt ice.
Latent heat is the energy needed for a substance to change a state without changing its temperature.
6.3 - Changes of state
Energy is needed to melt a solid or boil a liquid.
Boiling point occurs throughout a liquid at it's boiling point. Evaporation occurs from surface of a liquid when it's temperature is below its boiling point.
For a pure substance
It's melting point is the temperature at which it melts (same temp as when it solidifies)
It's boiling point is the temperature at which it boils (same temp at which it condenses)
The flat section of a temperature-time graph gives the melting point or the boiling point of a substance
6.2 - States of matter
The particles of a liquid move about at random and are in contact with each other. They are more energetic than particles in a solid.
The particles of a as move about randomly and are far apart. They are the most energetic of the states of matter.
The particles of a solid are held next to each other in fixed positions. They are the least energetic of the states of matter.
When a substance changes state, its mass stays the same because the number of particles stays the same.
6.4 - Internal energy
The strength of the forces of attraction the particles of a substance explains why is it a solid, a liquid, or a gas.
When a substance is heated
If it melts of it boils, the potential energy of its particles increases
If its temperature rises, the kinetic energy of its particles increases.
Increasing the temperature of a substance increases its internal energy.
The pressure of a gas on a surface is caused by the particles of the gas repeatedly hitting the surface.
6.6 - Gas pressure and temperature
If the temperature of a gas in a sealed container is increases, the pressure of the gas increases because;
Because
The molecules move faster so they hit the surfaces with more surface.
The number of impacts per second of gas molecules on the counter increases.
The pressure of a gas is caused by the random impacts of gas molecules of surfaces that are in contact with the gas.
The unpredictable motion of smoke particles in air is evidence of the random motion of gas molecules.