1.
Energy<br />Kinetic energy (EK)<br />Potential energy (EP)<br />Energy due to motion<br />Energy due to position (stored energy)<br />What is Energy?<br />
2.
Total Energy = Kinetic Energy + Potential Energy<br /> E = EK + EP<br />Kinetic energy & potential energy are interchangeable<br />Ball thrown upwards slows & loses kinetic energy but gains potential energy<br />The reverse happens as it falls back to the ground<br />
3.
Law of Conservation of Energy: the total energy of the universe is constant and can neither be created nor destroyed; it can only be transformed.<br />The internal energy, U, of a sample is the sum of all the kinetic and potential energies of all the atoms and molecules in a sample<br />i.e. it is the total energy of all the atoms and molecules in a sample<br />
4.
State Functions<br />A property of a system that changes independently of its pathway<br />Energy changes this way<br />
5.
Temperature vs. Heat<br />Temperature (T) is a measure of the kinetic energy of particles’ random motion <br />(°C, °F or K)<br />Heat (q) is a measure of the total amount of energy transferred from an object of high temperature to one of low temperature<br />(J or cal)<br />
6.
How do we relate change in temp. to the energy transferred?<br />Heat capacity (J/oC) = heat supplied (J)<br />temperature (oC)<br />Heat Capacity = heat required to raise temp. of an object by 1oC<br /><ul><li> more heat is required to raise the temp. of a large sample of a substance by 1oC than is needed for a smaller sample</li></li></ul><li>Specific Heat<br />In order to relate heat and temperature we use the specific heat capacity.<br />Cp- it is a physical property<br />units are J/g°C<br />Water’s Cp = 4.18 J/g °C<br />
7.
The Ultimate Formula (not really)<br />The heat energy needed to raise a substance to a certain temperature is related to the mass of the substance and the temperature change (ΔT)<br />q = mass x specific heat x temperature change<br />q = m CpΔT<br />
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