Thermal properties of materials
- Created by: Laylalink27
- Created on: 30-04-17 11:50
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- Thermal properties of materials
- Specific latent heat of fusion or vaporisation is the thermal energy required to change state of 1kg of substance. The larger the mass, the more energy it takes to change its state. This is why specific latent heat is defined per kilogram
- To melt a solid, you need to break the bonds that hold particles in place.
- The energy needed for this is the latent heat of fusion.
- When you boil or evaporate a liquid, energy is needed to pull the particles apart.
- This energy is called the latent heat of vaporisation
- When you boil or evaporate a liquid, energy is needed to pull the particles apart.
- The energy needed for this is the latent heat of fusion.
- Latent heat energy melts ice
- energy change=change in mass.Specific latent heat: E (J)=mL (J.kg^-1)
- L(v)=latent heat of vaporisation and L(f)=latent heat of fusion
- Measuring the specific latent heat of a solid or a liquid
- For a solid like ice: 1) Put a heating coil and equal masses of ice in two funnels above beakers 2) Turn on one heating coil for 3 minutes. Record the energy transferred in 3 minutes. Don't turn on the other coil-it is there so you can measure how much ice melts due to ambient temperature of room. 3) At end of 3 minutes, measure mass of water collected in beakers. Subtract one from the other to get mass of ice that melted solely due to heater. 4)E=mL so to find specific latent heat of fusion for water divide energy by mass of ice that melted.
- For a liquid: 1) boil water in a distilling flask and condense the vapour given off and divide energy transferred by this mass.
- For a solid like ice: 1) Put a heating coil and equal masses of ice in two funnels above beakers 2) Turn on one heating coil for 3 minutes. Record the energy transferred in 3 minutes. Don't turn on the other coil-it is there so you can measure how much ice melts due to ambient temperature of room. 3) At end of 3 minutes, measure mass of water collected in beakers. Subtract one from the other to get mass of ice that melted solely due to heater. 4)E=mL so to find specific latent heat of fusion for water divide energy by mass of ice that melted.
- energy change=change in mass.Specific latent heat: E (J)=mL (J.kg^-1)
- To melt a solid, you need to break the bonds that hold particles in place.
- Specific latent heat of fusion or vaporisation is the thermal energy required to change state of 1kg of substance. The larger the mass, the more energy it takes to change its state. This is why specific latent heat is defined per kilogram
- Specific heat capacity=energy required to raise temperature of 1kg by 1K
- E=mc.change in T so E=2x30x4180=250,800J which is approx. 250kJ
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- E=mc.change in T so E=2x30x4180=250,800J which is approx. 250kJ
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