Heat+Affect+a+System

=__How Does Heat Affect a System?__=

By Ms. Arienzo

__**Key Vocabulary:**__ Heat, Thermal energy, temperature, Solid, liquid, gas.

All objects have __thermal energy__. __Thermal energy__ is the the kinetic energy associated with the particles. __Temperature__ is the measure of the average kinetic energy of a substance. While __Heat__ is the transfer of thermal energy from high temperature to low temperature.

Therefore, a cup of tea at 80 degrees Celsius has less thermal energy than a pool at 30 degrees Celsius because the pool has more molecules. So.... what happens when heat is added to a system?



Well we know from above that heat moves from high temperature to low temperature. If we take an ice cube and put it on a hot plate, the heat will move from the hot plate to the ice cube. Eventually, if we heat it enough the __solid__, it will turn to a l__iquid__. Therefore, by adding thermal energy, a change in state can occur. How do we know that thermal energy is added? Well we know the particles in a __solid__ move very slowly and in a l__iquid p__articles move faster. (Remember the ice cream lab?) Additionally, as heat is being added and the thermal energy is increasing, the temperature actually remains the same as melting is occurring. Check out the graph below to see how temperature changes with changes in state.

What happens when we add heat to the liquid water? If we add enough heat, the water will turn to a gas! Again, the particles are moving much faster in the __gas phase__ than in the liquid phase therefore we know that the thermal energy is greater. Remember how we were able to blow up the party balloon in lab by heating water? Also as the thermal energy is increasing the temperature does not increase as the liquid is turning into a gas. This is also shown in the graph above.

The application to the real world is that if I was super hungry and wanted to cook some pasta and need to boil water, I would be best off using less water which will boil quicker than alot of water because it will need less energy. So my pot of boiling water should look like the second one in the example below.

Here's a link to the BBC website that tells us more about adding heat to a system: [|Click Here]

Here's a cool video showing how water can absorb heat and not change temperature: media type="custom" key="11005216"