Do Now – name and count the atoms

1. CO2

• Carbon: 1• Oxygen: 2

2. 2NaAu(CN)2 • Sodium: 2• Gold: 2• Carbon: 4• Nitrogen: 43. 3N(O2H2)2

• Nitrogen: 3• Oxygen: 12• Hydrogen: 12

Example: BaBr2 Barium: 1Bromine: 2

Homework and Announcements

• USA TestPrep (due Mondays)• Finish independent practice problems (slide 23)• Summary

• Test Averages – A List

Title: Endo vs Exo

L.O. SWBAT determine if a reaction is endothermic or exothermic.

Chemical Bond Review – Polar vs Non Polar

Reactants: Will be changed into new substance.

What you start with.

Products: New Substance formed

What you end up with.

REACTANTS PRODUCTS

Thermal Energy: “Movement of Heat”

FLOWS: warmer matter to cooler matter.

Chemical Reactions: Released or absorbed Higher temperature = faster particles = more thermal

energy

Which of the following has more thermal energy?

A melted chocolate bar.

A solid chocolate bar.

Why?

Higher temperature = higher thermal energy

Exothermic vs Endothermic

Endothermic change: Endo - In Thermos - heat Example:

Ice + Heat Water (Physical change) Ca + Cu + Heat CaCu (Chemical change)

Heat is absorbed (heat is taken in) Heat is a reactant.

Which of these is endothermic?

Liquid water changes to Solid ice

Solid ice changes to Liquid water

Why?

Heat is absorbed so the particles move faster.

Exothermic change: Exo - Out Thermos - Heat Example:

2Mg + O2 Heat + Light + 2MgO (Chemical change) Water Heat + Ice (Physical change)

Heat is released (heat exits) Heat is a product.

Which of these is a exothermic change?

Instant cold packs

Instant hand warmer pack

Why?

Because the hand warmer is releasing heat.

Pair Share

• 1. Photosynthesis. • (CO2 + H2O + Energy O2 + Glucose)

• Endothermic. Energy is a reactant.• 2. Fireworks exploding?• Exothermic.

• Powder + O2 Heat + Light + Gas• 3. Baking a cake?• Endothermic. Batter + Heat Cake

Endothermic or Exothermic, Why?

“Elephant Toothpaste”

2H2O2 2H2O + O2

1. Is this equation balanced?2. releases heat or absorbs heat?3. Is the heat a reactant or a product?4. Endothermic or Exothermic?

17

Elephant Toothpaste

“Elephant Toothpaste”

2H2O2 2H2O + O2

1. Is this equation balanced?2. releases heat or absorbs heat?3. Is the heat a reactant or a product?4. Endothermic or Exothermic?

19

Fire with Science Bob

Problem 1Problem 2

• Circle the reactants• Underline the products

• Is the equation endothermic or exothermic?

• Is the equation balanced? (Does it Show conservation of matter?)

2NaClO3 2NaCl + 3O2 + heat C3H8 + 3O2 + heat 3CO2 + 4H2O

• Circle the reactants• Underline the products

• Is the equation endothermic or exothermic?

• Is the equation balanced? (Does it Show conservation of matter?)YES

NO( Na:2 Cl:2 O:6 Na:2 Cl:2 O:6)

( C:3 H:8 O:6 C:3 H:8 O: 6+4=10)

Summary – 5 minutes silent writing time

1. When looking at a chemical equation, how do you determine if it follows the law of conservation of matter?

2. What is the difference between endothermic and exothermic reactions?

3. Give an example of an endothermic reaction.4. Give an example of an exothermic reaction.

Independent WorkName each atom found in the following compounds and determine how many atoms of each element are present:

1) CaF2

2) Be(OH)2 3) NO2 4) Al2(SO4)3

5) NH4NO3

6) S2F2

7) Na2CO3

8) CH4