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Agenda:. Warm-up: Word Equations Chemical reactions and energy Endothermic or exothermic How energy is represented in chemical reactions Practice: Predicting products Using types of reactions Cards. Homework :. #13 Zinc II hydroxide + hydrochloric acid Zinc II chloride + water - PowerPoint PPT Presentation
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Agenda: Warm-up: Word Equations Chemical reactions and energy Endothermic or exothermic How energy is represented in chemical reactions Practice: Predicting products Using types of reactions Cards Homework:
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Page 1: Agenda:

Agenda:

Warm-up: Word Equations Chemical reactions and energy

Endothermic or exothermic How energy is represented in chemical

reactions Practice: Predicting products

Using types of reactions Cards

• Homework:

Page 2: Agenda:

WORD EQUATIONS: HAND-INWRITE THE FORMULAS AND BALANCE

#13 Zinc II hydroxide + hydrochloric acid

Zinc II chloride + water

#17 Sodium carbonate + sulfuric acid Sodium sulfate + water + carbon dioxide

Page 3: Agenda:

ENERGY IN REACTIONS

Representing the energy changes in reactionsThermo-chemistry

Page 4: Agenda:
Page 5: Agenda:

Representing energy in chemical reactions1. Measurement of energy: joules

Joules/gram or joules/mole2. Energy shown as a reactant or product

Endothermic: Exothermic:

3. Change in energy: ∆H (heat of reaction) Positive + ∆

Negative -∆4. Diagrams of the energy

Page 6: Agenda:

ENERGY IN REACTIONS

Exothermic reactions• Energy is given out

• The products have less energy than the reactants

Exothermic reactions are common.

Combustion and neutralization (a special type of double replacement reactions) are exothermic

Page 7: Agenda:

ENERGY LEVEL DIAGRAMS

Exothermic reactions

energy

Page 8: Agenda:

ENERGY LEVEL DIAGRAMS

Exothermic reactions

energy

course of reaction

Page 9: Agenda:

ENERGY LEVEL DIAGRAMS

Exothermic reactions

energy

course of reaction

reactants

Page 10: Agenda:

ENERGY LEVEL DIAGRAMS

Exothermic reactions

energy

course of reaction

reactants

products

Page 11: Agenda:

ENERGY LEVEL DIAGRAMS

Exothermic reactions

energy

course of reaction

reactants

products

energy given out∆H is negative

Page 12: Agenda:

ENERGY LEVEL DIAGRAMS

Endothermic reactions

• Energy is taken in

• The products have more energy than the reactants

The energy is taken in from the surroundings

Page 13: Agenda:

ENERGY LEVEL DIAGRAMS

Endothermic reactions

energy

Page 14: Agenda:

ENERGY LEVEL DIAGRAMS

Endothermic reactions

energy

course of reaction

Page 15: Agenda:

ENERGY LEVEL DIAGRAMS

Endothermic reactions

energy

course of reaction

reactants

Page 16: Agenda:

ENERGY LEVEL DIAGRAMS

Endothermic reactions

energy

course of reaction

reactants

products

Page 17: Agenda:

ENERGY LEVEL DIAGRAMS

Endothermic reactions

energy

course of reaction

energy taken in∆H is positivereactants

products

Page 18: Agenda:

SUMMARY TABLE

Exothermic reactions

Endothermic reactions

Page 19: Agenda:

SUMMARY TABLE

Exothermic reactions

Endothermic reactions

Energy is given out to the surroundings

Energy is taken in from the surroundings

Page 20: Agenda:

SUMMARY TABLE

Exothermic reactions

Endothermic reactions

Energy is given out to the surroundings

Energy is taken in from the surroundings

∆H is negative ∆H is positive

Page 21: Agenda:

SUMMARY TABLE

Exothermic reactions

Endothermic reactions

Energy is given out to the surroundings

Energy is taken in from the surroundings

∆H is negative ∆H is positive

Products have less energy than reactants

Products have more energy than reactants

Page 22: Agenda:

∆H = ENTHALPY = CHANGE IN ENERGY

How much energy is given out or taken in?

• Energy is needed to break chemical bonds

• Energy is given out when bonds are made

∆H is the difference between the energy needed to break the bonds in the reactants, and the energy given out when new bonds are made in the products

Page 23: Agenda:

WORKING OUT ∆H

Summary

• The energy values have units of kJ/mole

∆H is difference between energy in – energy out

• Energy goes in to break bonds

• Energy goes out when bonds are made

Page 24: Agenda:

Practice: Reactions

Determine types of reactions Determine if the reaction is

endothermic or exothermic

Page 25: Agenda:

ENERGY


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