Bellringer O Why are detailed steps important when recording procedure in a laboratory setting?

Heat Transfer and Phase Change O Phase Change: when matter changes state O i.e. solid  liquid, gas  solid, etc O Thermal energy gained or last during a phase change does NOT change the temperature of the substance.

Where does the energy go? O When heating, energy goes into pulling molecules in the substance apart, allowing them to more freely move O When cooling, the particles become bound together before slowing down any more.

Heating curves

Create a heating curve for water

Measuring the thermal energy O Heat of fusion (H f ) O A constant used to determine heat gained to melt a solid or lost to freeze a liquid O Q=mH f O Measured in J/kg O Varies by material

Create a heating curve for water

Measuring the thermal energy O Heat of vaporization (H v ) O A constant used to determine heat gained to boil a liquid or lost to condense a gas O Q=mH v O Measured in J/kg O Varies by material

Practice 1 O How much heat does it take to melt 3 kg of ice. Heat of fusion for ice/water is 3.34 x 10 5 J/kg

Practice 2 O John places 245 g of ice at -4 degrees C into a beaker and heats it over a burner until it is 35 degree C water. How much heat was used?

Step 1 O Identify states of matter and phase changes involved and sketch a picture

Step 2 O List givens and include the temperature where the phase change occurs.

Step 3 O Create an equation for each state of matter and each phase change

Step 4 O Plug in values and solve

Step 5 O Add all heat values together