2. THE LAW OF CONSERVATION
OF ENERGY
Energy can not be created or destroyed

3. System and Environment
System
System is the substance, the reaction, a process
that became the center of attention (object)
Environment
The environment is everything that is related
to the system

4. Lets check it out
Example:
substance A and substance B is
inserted into the test tube
System: substance A and
substance B
Environment: test tubes and air

5. Types of system
1. Open System
If the system and the environment can
experience, exchange of matter and energy
2. Closed System
If the system and the environment can not
be exchanged material, but it can be an
exchange of energy
3. Isolated System
In system and the environment can not be
an exchange of energy and matter

6. The sign for the heat and work
• System received heat
q (+)
• System released heat
q (-)
• System does work
w (-)
• System received the work
w (+)

7. Internal Energy (E)
the amount of energy possessed
by an agent or system
ΔE = EP - ER

8. Reaction of Heat
1. If reaction is reacting in closed
system, with fixed volume
(ΔV=0), where if ΔV=0 there is
no work in there(w=0)
So
ΔE= q

9. 2. If reaction is reacting in opened
system, with fixed pressure
, where may system do or
received work
So
ΔE= q + w

10. Exothermic Reaction
• Chemical reactions that are
accompanied by the release of heat
• Release heat from system to
surrounding
• H product < H reaction
• Sign of ΔH is always (-)

11. Exothermic Reaction
Reactants  Products + Energy
Energy of reactants
Energy of products
Energy
Reactants
- H
Products
Reaction Progress

12. Endothermic Reaction
• Chemical reactions that are
accompanied by the absorption of
heat
• Absorb heat from surrounding to
system
• H product > H reaction
• Sign of ΔH is always (+)

13. Endothermic Reaction
Energy + Reactants  Products
Energy
Activation Products
Energy
Reactants
+ H Endothermic
Reaction progress

14. Thank you for your attention
 There is a price for you in next slide
 Attention pleaseeeeeee!!

15. THERMOCHEMISTRY 1
Influenced by involving
4
5 7 8
2 3
6
causing
9 10
12 11

16. Statement to find the key-word :
1. Energy cannot be destroyed or created
2. the part of the universe on which we focus our attention in a certain
experiment
3. the parts of the universe that interact instantly with the system or
anything that restricts the system
4. may heat exchange between system and surrounding and matter
movement
5. may heat exchange between system and surrounding and not matter
movement
6. impossible for heat exchange between system and surrounding
7. subtracting the enthalpy of the reactant from the enthalpy of product
8. energy contained in a substance at temperature of 25oC and pressure of 1
atm.
9. a chemical reaction in which heat is absorbed from the surroundings
10.a chemical reaction in which heat is released from the system
11.Symbolize for enthalpy of the system falls.
12.Symbolize for enthalpy of the system rises.

17. THERMOCHEMISTRY Law of Conservation of
Energy
Influenced by involving
OPENED
ENTHALPY ENTHALPY
CLOSED SYSTEM SURROUNDINGS CHANGE
ISOLATED
causing
ENDOTHERMIC EXOTHERMIC
REACTION REACTION