# April 17, 2012

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27 Οκτ 2013 (πριν από 4 χρόνια και 6 μήνες)

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April 17, 2012

AGENDA:

1

Bell Ringer & Part. Log

2

Review HW

3

CN: Thermodynamics &
Hess’s Law

4

Work Time:
Thermodynamics & Hess’s
Law

Today’s Goal:

Students will be able to calculate
enthalpy using Hess’s Law.

Homework

1.
Thermodynamics & Hess’s
Law

2.
Extra Credit Work from
WEEK 30 is due Friday

Cornell Notes

Topic:

Thermodynamics & Hess’s Law

Date:

4/17/2012

Measuring energy:

Universe =
Surroundings

+
System

Surroundings

Surroundings

System

Heat

Heat

Endothermic

Exothermic

Review
from
yesterday

Cornell Notes

Heat Curve

= shows how temperature of the
surroundings

are changing during a chemical
reaction.

Diagram
Heat
Curves.

Temperature

Time

Exothermic

Temperature

Time

Endothermic

Temp. of
surroundings
will
increase
.

Temp. of
surroundings
will
decrease
.

Cornell Notes

Enthalpy “energy” (H)

= a measure of the
amount of heat “energy” in a
system

at
constant pressure

Hess’s Law:

H =
H
products

H
reactants

(Joules, J)

(

= “change in”)

Describe
enthalpy
& Hess’s
Law.

Enthalpy (J)

Time

Endothermic

Enthalpy (J)

Time

Exothermic

Cornell Notes

Reaction Coordinate Diagram

= shows
changes in enthalpy (heat) of a
system
.

Describe
Reaction
Coordinate
Diagrams.

Reactants have
more heat than
products

Products have
more heat than
reactants.

R

R

P

P

H =
+

H =
-

Cornell Notes

Summarize
what you
have
learned
today.

Thermodynamics

= study of
heat

movement

Energy (system) is
inverse

to temperature
(surroundings).

Enthalpy

Time

Enthalpy

Time

Examples

Hess’s Law:

H = H
P

H
R

H = 600 J

100 J

H = + 500 J

endothermic

H = H
P

H
R

H = 200 kJ

1000 kJ

H =
-

800 kJ

exothermic

H
R
=100J

H
P
=600J

H
P
=200kJ

H
R
=1000kJ