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REVIEW TIME!. What type of energy cooks food in a microwave oven? ELECTROMAGNETIC ENERGY What type of energy is the spinning plate inside of a microwave oven? MECHANICAL ENERGY. What type of Energy?. Kinetic + Potential! (Mechanical energy). QUIZ TIME!.

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Review time
REVIEWTIME!

What type of energy cooks food in a microwave oven?

ELECTROMAGNETIC ENERGY

What type of energy is the spinning plate inside of a microwave oven?

MECHANICAL ENERGY


What type of energy
What type of Energy?

Kinetic + Potential!

(Mechanical energy)


Quiz time
QUIZ TIME!

Electrical energy is transported to your house through power lines.

When you plug an electric fan to a power outlet, electrical energy is transform into what type of energy?

MECHANICAL ENERGY


Quiz time1
QUIZ TIME!

What energy transformation occurs when an electric lamp is turned on?

ELECTRICAL ENERGY

ELECTROMAGNETIC ENERGY

(Light energy)


Energy transfer
Energy Transfer

Sound

(mechanical)

Electrical

Thermal

Mechanical

Electrical

Chemical

Electrical

Light

(Electromagnetic)


Do now you have 10 minutes work quickly
Do Now-YOU HAVE 10 minutes. Work Quickly!

  • Get with your group.

  • Complete your group worksheet.

  • Practice your presentation ATLEAST once.

  • Designate one person in your group to hold up the appropriate types of energy cards at the end of the presentation.

    Make this OSCAR-worthy!!


And the oscar goes to
And the Oscar goes to…

  • Take a piece of scrap paper and rip it into 3 parts

  • On one piece, nominate someone for BEST ACTOR

  • On another piece, nominate someone for BEST SUPPORTING ACTOR

  • On the last piece, nominate a BEST MOVIE (list the scenario you enjoyed seeing played out the best)


Thermochemistry
Thermochemistry

  • The study of heat change in chemical reactions.


Heat change in chemical reactions
Heat Change in Chemical Reactions

  • For a chemical reaction to occur, bonds must be both formed and broken

    Fe + CuSO4 Cu + FeSO4

  • Energy is needed to break bonds.

  • Energy is released when bonds are formed.


2H2(g) + O2(g) 2H2O (l) + energy

H2O (g) H2O (l) + energy

energy + 2HgO (s) 2Hg (l) + O2(g)

energy + H2O (s) H2O (l)

Exothermic process is any process that gives off heat – transfers thermal energy from the system to the surroundings.

Endothermic process is any process in which heat has to be supplied to the system from the surroundings.

6.2


Thermochemical equations
Thermochemical Equations

  • 4Fe (s) + 3O2 (g) 2Fe2O3 (s) + 1625 kJ

  • Does this reaction give off heat or absorb heat?

  • Exothermic or endothermic?


Thermochemical equations1
Thermochemical Equations

  • C (s) + 2S (s) + 89.3 kJ  CS2 (l)

  • Is heat released or absorbed in this chemical reaction?

  • Exothermic or endothermic?


Enthalpy (H) is used to measure the heat flow into or out of a system in a process that occurs at constant pressure.

DH = H (products) – H (reactants)

Hproducts < Hreactants

Hproducts > Hreactants

DH < 0

DH > 0

6.3


Enthalpy heat flow is measured in
Enthalpy(heat flow) is measured in:

  • Joules (J)

  • Kilojoules (kJ)

  • 1 kJ = 1000 Joules


Energy level diagrams
Energy Level Diagrams

Endothermic reactions

products

energy

energy taken in

is positive, ∆H is positive

reactants

The products are higher in energy than the reactants

time of reaction


Energy level diagrams1
Energy Level Diagrams

Exothermic reactions

Energy given out

is negative; ∆H is negative

reactants

energy

products

Time of reaction

The products are lower in energy than the reactants



Endothermic or exothermic1
Endothermic or Exothermic?

What does DH equal?

80kJ-160kJ = -80kJ

DH = H (products) – H (reactants)


Endothermic or exothermic2
Endothermic or Exothermic?

What does DH equal?

DH = H (products) – H (reactants)


Endothermic or exothermic3
Endothermic or Exothermic?

What does DH equal?

DH = H (products) – H (reactants)


Endothermic or exothermic4
Endothermic or Exothermic?

Exo!

Endo!

What does DH equal?

DH = H (products) – H (reactants)



Consider this reaction
Consider this reaction:

  • 2C2H6 + 7O2 → 4CO2 + 6H2O + 3120 kJ

    a. endothermic or exothermic?

    b. If 28 moles of oxygen are reacted, how much energy will be produced?

exothermic

3,120 x 4 = 12, 480 kJ


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