Density

• density: the degree of compactness of a substance
• density is measure in kg/m3 and is the mass of an object per unit volume
• In density practical, if the object is irregular you use a eureka displacement can to calculate the density.
• Solids have a higher density than gases due to the particles being closer together/more compact.
• Density = Mass / Volume
• The greater the temperature, the lower the density of a liquid or solid as the particles move further apart from one another.
• Liquid has a higher density than gas because it's more compressed so there are more molecules packed into the same space.
• To find the volume of an irregular shaped object, fill it with water and weigh it then subtract the weight of the empty container from this value.
• The greater the pressure on a gas, the higher its density because it compresses the particles more closely together.
• A change in state will cause a change in density. For example, when water freezes, it becomes less dense so floats on top of the denser liquid below (water).
• Gas has a lower density than liquids because they are less compressed so there are fewer molecules packed into the same space.
• When a liquid evaporates, some of the molecules escape into the air above forming a vapour. The remaining molecules are left with more space between them which increases their average speed and causes the liquid to become less dense.
• A substance with a high melting point will be denser at room temperature compared to a substance with a low melting point.
• If the mass of the object is less than that of the water used to displace it, the object must be less dense than water.
• A gas will expand when heated because the increased kinetic energy causes the particles to collide more frequently and violently which increases their average speed and distance between them.
• Gas have high kinetic energy due to the particles being able to move freely in random directions rapidly.
• If particles are compressed in a gas, the density will be higher due to the particles being closer together.
• The greater the pressure on a gas, the smaller its volume becomes as the particles get pushed closer together.
• Increasing the pressure on a gas decreases its volume.
• Volume= how big object is.
• mass= how heavy object is.
• A liquid has a fixed shape but takes up the shape of whatever container it is put into.
• Density can also be calculated by dividing the mass of an object by it's volume.
• Different liquids have different densities.