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

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Presentation on theme: "Bellringer O Why are detailed steps important when recording procedure in a laboratory setting?"— Presentation transcript:

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

2 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.

3 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.

4 Heating curves

5 Create a heating curve for water

6

7 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

8 Create a heating curve for water

9 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

10 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

11 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?

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

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

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

15 Step 4 O Plug in values and solve

16 Step 5 O Add all heat values together


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