The document discusses key concepts in thermodynamics and thermochemistry including: 1) Thermochemistry is the study of energy changes that occur during chemical reactions. Reactions can be exothermic, releasing heat from the system, or endothermic, absorbing heat into the system. 2) The enthalpy change (ΔH) of a reaction indicates whether it is exothermic (negative ΔH) or endothermic (positive ΔH). 3) A system exchanges energy with its surroundings during chemical or physical changes. Exothermic reactions increase the temperature of the surroundings while endothermic reactions decrease it.

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WEEK 9:
ENERGY CHANGES IN
CHEMICAL REACTIONS

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Jumble!
Start!

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1. TEHROMTRYISMCHE

5. THERMOCHEMISTRY
is the study of energy
changes that occur during
chemical reactions.

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2. YNREGE

7. ENERGY
is the ability to do work or
transfer heat.

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3. THEA

9. HEAT
is a form of energy transfer
between two objects as a
result of their difference in
temperature.

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4. STEMSY

11. SYSTEM
a component or set of
components of interest

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5. SOUNDRURINGS

13. SURROUNDINGS
everything that a system can
exchange energy with,
everything touching / connected
to it

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6. ETHOXERCIM

15. EXOTHERMIC REACTIONS
are reactions or physical
changes in which the system
loses heat.

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7. EDNOHTERCIM

17. ENDOTHERMIC REACTIONS
are reactions or physical
changes in which the system
absorbs heat.

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8. ENHTLAYP

19. ENTHALPY
is the heat content of a
system.

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9. TERMOHDAYNICSM

21. THERMODYNAMICS
is the study of energy and
its transformations.

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ENERGY CHANGES IN
CHEMICAL REACTIONS
Chemical processes release or absorb energy.

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THERMODYNAMICS THERMOCHEMISTRY

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Energy
& Heat

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Energy and Heat

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Energy
and
Heat

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THERMOCHEMISTRY
Focus is on the heat and matter transfer between the system and
the surroundings

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THREE TYPES OF SYSTEMS

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THREE TYPES OF SYSTEMS

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HEAT AND
HEAT FLOW
Heat flows from
higher- temperature object
to lower-temperature object.
EXOTHERMIC REACTION
ENDOTHERMIC REACTION
energy ENters
energy EXits

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The enthalpy change of the reaction,
∆H has a negative value
EXOTHERMIC REACTION ENDOTHERMIC REACTION
The enthalpy change of the reaction,
∆H has a positive value
ΔH=(ΔHproducts -ΔHreactants)

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EXOTHERMIC REACTION ENDOTHERMIC REACTION
 are chemical reactions that
release heat to the surrounding.
 Energy is released from the
system.
 Temperature increases with
progression of the reaction.
 Enthalpy of reactants is higher
than that of the products.
 Change in enthalpy (∆H) is a
negative value.
 are chemical reactions that
absorb heat to the surrounding.
 Energy should be given to the
system.
 Temperature decreases with
progression of the reaction.
 Enthalpy of reactants is lower
than that of the products.
 Change in enthalpy (∆H) is a
positive value.

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Thank you!