1. Science Starter (week 14, Day 4, 5/5/16)
7.1 Homework on desk!
1) Look at the heating curve learned about yesterday. Describe where phase energy is increasing and where thermal energy is increasing.
You have a tea kettle of water boiling on a stove. If you turn up the burner would the temperature of the water change? Explain your answer.
3) Put the following elements in order of increasing electronegativity. C, B, O, N

2. SWBAT identify the parts of the heating and cooling curve
Objective
SWBAT identify the parts of the heating and cooling curve
Understand the difference between thermal and phase energy
SWBAT describe heat capacity

3. Agenda
Science Starter
Re-loop Yesterday
Demo: Dolla Dolla Billz
Identifying Heat Equations and Practice
Poster book Work Time

4. QUICK CHECK
When phase energy is increasing, temperature _________________.
When thermal energy is increasing, phase energy ________________.
What happens to temperature as I melt a block of ice?
What does a cooling curve look like?

5. Why doesn’t the temperature increase during melting and evaporating?
HEAT is constant but the energy changes at a weird rate.
WHY? Because of the difference between thermal energy and phase energy.
Thermal energy changes temperature
Phase energy breaks down phases

6. Unit 7: Heat and Energy Specific Heat Quantitative Energy Problems

7. Demo: Dollar Dollar Bills
Background Info:
Law of Conservation of Energy: Energy is neither created nor destroyed, it is only transferred.
Eye Level:
Particle Level:

8. Demo: Dollar Dollar Bills
Notes
Demo: Dollar Dollar Bills
Consensus:
Heat capacity (also called “specific heat”) = amount of energy required to raise the temperature of one gram of that substance by one degree Celsius
We measure energy in joules (J)

9. It’s Happened to you:
It’s a hot summer day. You get into your car. The seatbelt is BURNING hot (ouch!)
However, a bottle of water you left in the back seat is only slightly warm.
WHY????!

10. Heat Capacities of Common Substances
Heat capacity (J/g C)
Water (l) liquid
4.18
Water (s) solid
2.1
Alcohol
2.44
Aluminum
0.897
Gold
0.129

11. Specific Heat Like Specific Pain?
Low Specific Pain: Ribs and other sensitive areas – LOW TOLERANCE FOR PAIN = Quicker Cringing!
High Specific Pain: Arms and legs – HIGHER TOLERANCE FOR PAIN = Less Cringing!

12. We can write this value as:
It takes 4.18 joules to raise the temperature of 1 g of liquid water by 1 C.
We can write this value as:
Suppose that we have a larger sample of liquid water. How much energy would it take to raise the temperature of 5 g of water by one degree Celsius?
How much energy would it take to raise the temperature of 5 g of water by 2 degrees Celsius?

13. q = quantity of energy transferred (in J) m = mass (in g)
You just derived this equation:
q = quantity of energy transferred (in J)
m = mass (in g)
C = heat capacity (J/g ⁰C)
∆T = change in temperature (in⁰ C)
∆T = Tfinal – Tinitial
What is absolute value???
Write!

14.  How could we graph this on a heating/cooling curve?
How much energy does it take to raise the temperature of 5 g of water by 2 degrees celsius?
 How could we graph this on a heating/cooling curve?

15. What is happening to the substance?
Which Heat Equation?
Notes
What is happening to the substance?
Use This Equation
Freezes or melts
Evaporates or condenses
Temperature changes

16. Energy Constants (H2O)
Heat of fusion, Hf= 334 J/g
(amount of energy required to melt or freeze 1 g of H2O)
Heat of vaporization, Hv = 2260 J/g
(amount of energy required to evaporate or condense 1 g of H2O)
Heat capacity (C) of solid H2O =
2.1 J/g˚C
Heat capacity (C) of liquid H2O = 4.18 J/g˚C

17. Wait! Which equation do I use??!!
A cup of hot chocolate (270 g) cools from 60˚C down to comfortable room temperature 20.˚C. How much energy does it release to the surroundings?
First, before you do any math, you need to determine what changes are taking place.

18. What changes are taking place?
Steps
What changes are taking place?
(Is temperature changing? Is phase changing?)
2. Which heat equation?
Identify variables.
Plug in and solve.

19. Another example on your worksheet… 2
Another example on your worksheet… 2. A 110g cup of water spills on your kitchen floor. If all of the water evaporates, how much energy did the water absorb from the surroundings? Identify info – Strategy (equation) –

21. Partner Practice
3. You accidentally left your flavor-ice popsicle, with a mass of 43g at 0˚C,on a park bench during the summer. By the time you got back from the basketball court it is totally melted. How much energy must be absorbed by the ice in order for it to melt all the way? (assume no temperature change) Identify info – Strategy (equation) –

22. Tell me which heat equation and WHY?
1. There is a 150 g puddle of water at 0C outside. It freezes overnight. How much energy was required to freeze the water? 2. A 320 g cup of iced tea warms on a summer day from 10 degrees Celsius to 40 degrees Celsius. How much energy was required? 3. If q is positive, this means that heat was (lost)/(gained).

23. Mini Poster Book Work Time
Use this time to work on your Semester Mini Poster Book (Units 1-3 should be complete)
Instructions and materials are located at the front table