Properties of Matter

Properties of Matter Glossary Slide 3-4: The Conservation of Energy Slide 5-6: Pressure, Force and Area Slide 7-11: Heat Energy Slide 12-13: Kelvin Temperature Scale Slide 14-15: Boyle’s (Pressure-Volume) Law Slide 16-17: Charles’ (Volume-Temperature) Law Slide 18-19: Gay-Lussac’s (Pressure-Temperature) Law Slide 20: All Gas Laws Combined Slide 21-22: The Kinetic Model

The Conservation of Energy There are 8 forms of energy. Chemical Electrical Heat Kinetic Light Nuclear Potential Sound

The Conservation of Energy For example, when a match is lit chemical energy turns into light and heat energy. The law of the conservation of energy states, “Energy cannot be destroyed nor created, it can only turn into different forms”. Or when a rollercoaster goes down a slope its potential energy turns into kinetic energy. Or when a car’s brakes are applied its kinetic energy turns to heat and sound.

Pressure, Force and Area The pressure that something experiences is dependent on how much force is being applied over a certain amount of area. P = F/A Pressure Force Area (Pascals) (Newtons) (squared metres) (Pa) (N) (m2) In Physics we say pressure is the force per m2.

Pressure, Force and Area Large surface area = smaller pressure P = F/A Small surface area = large pressure

Heat Energy Heat energy causes atoms to vibrate or move around more. Temperature is how we measure how much the atoms are vibrating/moving.

Heat Energy Some materials absorb heat energy better than others. How much heat energy a material needs to change a kilogram of the material by a temperature of 1oC is called the specific heat capacity. You can find this for different materials on your data sheet.

Heat Energy The amount of heat energy per kilogram of mass required to change the state of a material is known as the specific latent heat. If going from solid to liquid (or vice-versa) we call this the specific latent heat of fusion. If going from liquid to gas (or vice-versa) we call this the specific latent heat of vaporisation. These can be found on your data sheet for different types of materials. Materials need heat energy to change state (like from solid to liquid). The temperature doesn’t change when a material changes state though, this is why materials have an exact melting/boiling temperature.

Heat Energy Eh = cm∆T Eh = ml HEAT C o C Once the state is completely liquid, the temperature starts to increase again. 140 Heat Energy When a solid is heated up its temperature changes. 120 100 80 60 Eh = cm∆T 40 Changing Temperature, Constant State. When the melting point is reached the solid turns into a liquid, but the temperature remains constant, even when more heat energy is still being added. When the boiling point is reached the liquid turns into a gas, but the temperature remains constant, even when more heat energy is still being added. 20 -20 -40 Specific heat capacity (data sheet) Eh = ml Changing State, Constant Temperature Once the state is completely gas, the temperature starts to increase again. Specific latent heat of vaporisation (data sheet) Specific latent heat of fusion (data sheet) HEAT

Heat Energy

Kelvin Temperature Scale We mostly use degrees Celsius (oC) for temperature in Physics. The only exception is when we are looking at the physical laws for gases. In this case we measure temperature in Kelvins (K).

Kelvin Temperature Scale The temperature at which atoms have no heat energy at all (so not moving) is known as absolute zero. This occurs at -273 oC or on the Kelvin temperature scale 0 K. e.g. 10 oC 0 K or -273oC

Boyle’s (P-V) Law Boyle’s Law is one of the three gas laws. All three gas laws consider a set amount of gas inside a container. Boyle’s Law looks at the relationship between volume and pressure when the temperature of the gas is constant. “Pressure is inversely proportional to volume.”

Boyle’s (P-V) Law P1V1 = P2V2 = constant The inverse of volume. “Pressure is inversely proportional to volume.” P1V1 = P2V2 = constant The inverse of volume.

Charles’ (V-T) Law Charles’ Law is the relationship between volume and temperature when the pressure of the gas is constant. “Volume is directly proportional to temperature.”

Charles’ (V-T) Law V1 = V2 = constant T1 T2 “Volume is directly proportional to temperature.” V1 = V2 = constant T1 T2

Gay-Lussac’s (P-T) Law Gay-Lussac’s Law is the relationship between pressure and temperature when the volume of the gas is constant. “The pressure is directly proportional to the temperature”.

Gay-Lussac’s (P-T) Law “The pressure is directly proportional to the temperature”. P1 = P2 = constant T1 T2

All Gas Laws Combined P1V1 = P2V2 = constant T1 T2 If none of the variables (pressure, volume or temperature) are constant then all three gas laws combine into one. This equation does not appear on your equation sheet so you need to know it off-by-heart P1V1 = P2V2 = constant T1 T2

The Kinetic Model The kinetic model for gases is a way of visualising what happens when the pressure, temperature or volume of a gas is changed. “Using the kinetic model, explain...” questions regularly appear in National 5 Physics. Click the link to BBC Bitesize to get a better idea of what is happening when a fixed amount of gas is stored in a container. https://www.bbc.com/education/guides/zjc6fg8/video

The Kinetic Model T v freq. F A V P P = F/A It is important that you are able to explain what is happening by mentioning some key variables. These include temperature, particle speed, how frequently the particles hit off the container walls, the force which particles hit off the walls of the container with and the area and volume of the container. It is also important to go through the equation P = F/A at the end of your explanation. T v freq. F A V P P = F/A