1. Lithium + Magnesium Hydroxide 
Science Starter (Week 14, Day 5, 5/6/16)
HW 7.2 ON DESK
If it takes 340,000J to boil a sample of water, what is the mass of the sample?
How much energy is required to heat a 300g block of ice from -20°C to -5.0°C?
What kind of energy/energies do I have when I take a tray of room temperature water and freeze it?
Predict the product of the following reaction.
Lithium + Magnesium Hydroxide 

2. SWBAT calculate multi-step quantitative energy problems
Objective
SWBAT calculate multi-step quantitative energy problems

3. Poster Books Due Monday!
Agenda
Poster Books Due Monday!
Science Starter
Recap Yesterday
Multi-step Energy Problems
Practice/Work Time
HOMEWORK: FINISH WS #3

4. Today: Multi-step Quantitative Energy Problems
Unit 7 Schedule
Today: Multi-step Quantitative Energy Problems
Monday: Endothermic & Exothermic, Potential Energy
Tuesday: Laws of Thermodynamics
Wednesday: Phase Change Diagrams, Dry Ice Lab
Thursday: Unit 7 Review
Friday: Unit 7- Heat & Energy Test

5. Quick Check
What kind of energy(ies) are involved in the following problems? Draw the heating/cooling curve.
A polar bear take a block of ice at -30oC and melts it on his stove at home so he can drink the water.
A sample of water absorbs 2,478,000 J as it evaporates.
An ice cube cools down from -15C to -25C. How much energy was released?

6. Quick Check
4. An unidentified piece of 15 g of a metal absorbs 320 J of energy as it heats up from 20C to 50C. What is the identity of the metal?

7. Unit 7: Heat and Energy Multi-Step Problems

8. What happens during a two-step problem?
Multi-Step Problems!
What happens during a two-step problem?
What kinds of energy do we have?

9. Steps to Solving Multi-Step Problems
Read the question and identify any key words. Circle them!
Draw the heating/cooling curve.
Solve the individual parts of the problem.
Add them all together.

10. Multi-Step Example
1. A 50.0 g sample of liquid water at 0.0˚C ends up as ice at – 20.0 ˚C. How much energy is involved in this change?

11. Multi-Step Practice
2. Shanya begins with a 75g glass of 50°C water. She cools it to 0°C and then completely freezes it. How much energy was lost?

12. Multi-Step Practice
3. Danielle has 25g of water at 80°C and boils it completely into a gas at 110 °C. How much energy was lost?

13. 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