Download A roller coaster ride is a thrilling experience which involves a wealth

Do Now Clicker #
**
Name …………………………………………….
Team ……………………….
Title: intermolecular forces
Date ………………………
Which is the strongest type of intermolecular bond?
a. covalent
c. Dipole dipole
b. Hydrogen
d. Dispersion forces
2) What is strongest bond type?
a. Dipole dipole
b. covalent
c. Ion dipole
d. Hydrogen
**
Draw a Lewis diagram of ammonia NH3
*
What type of bonding holds the molecule together ___________________________
*
What type of bonding sticks different ammonia molecules together _________________
*
What is adhesion?
Explain what is meant by like dissolves like
Explain why nonpolar molecules usually have much lower surface tension than polar
ones
Rapid Knowledge
Name …………………………………………….
Team ………………………
Date ………………………
Title: Dimensional analysis
Using Dimensional analysis
What is the molecular mass of CO2
What is the mass of 0.4 moles of CO2
What volume would 1 mole of CO2 occupy at STP
What volume would 0.4 moles of CO2 occupy at STP
What volume (at STP) of CO2 is produced when 50g of CaCO3 is thermally decomposed
CaCO3
CO2 + CaO
What volume of 0.5 M HCl is needed to react completely with 20.0 grams of NaOH?
HCl + NaOH
NaCl + H20
Information sheet free energy and entropy
We have already learned that
Enthalpy is the change in internal chemical potential energy measured as heat
*
*
*
But now we must consider a new quantity which can help power a reaction
Entropy is a measure of the disorder of a system the more disordered the higher the
entropy.
Systems gain stability and entropy by being more disordered (randomized) so lets look
at some physical examples
Most disordered Gases, ions in solution, liquids. Solids
Both enthalpy and entropy combined help determine whether a reaction is going to
occur or not. If a reaction is likely to occur on its own then in some way the products
must be more stable than the reactants. In most cases this is because the products have
less chemical potential energy than the reactants (exothermic reactions).
However during endothermic reactions there is actually again in chemical potential
energy this means that the products should be less stable than the reactants and the
reaction should not occur. If such a reaction is accompanied by an increase in
randomness then this can balance out the increase in chemical potential energy. This
means reactions can end in more potential energy provided that there is an increase in
randomness.
*
So in 1873 Willard Gibbs worked out an equation for this it is called the Gibbs free
energy equation. Free energy refers to the fact that random systems are lower energy
than organized systems. Remember that to keep your binder organized takes effort all
forms of organization requires energy so if a system becomes disorganized it has
effectively lost energy
Gibbs free energy equation states
ΔG = ΔH – TΔS
*
Endothermic reactions always have an overall increase in the amount of disorder
Entropy has the symbol S
ΔS = q system / T system
2nd Law of thermodynamics state that over the entropy of the universe is increasing
and can also be written as q = TΔS
q -- energy transfered to or from a system
T -- Kelvin Temperature
ΔS greater than 0 when q for the system is positive (heat in)
ΔS less than 0 when q for the system is negative (heat out)
Unit for S is J/K
The total entropy change (ΔS) for a spontaneous process must be positive. This includes
surroundings, as well as system.
Entropy, unlike energy, need not be conserved--entropy increases when a natural
process occurs.
Reactions can also be classified according to the change in the free energy of the
reaction:


Endergonic - NON-SPONTANEOUS, G > 0
Exergonic - SPONTANEOUS, G < 0
Summary
Favorable
Conditions
Unfavorable
Conditions
H <0
H >0
S >0
S >0
SPONTANEOUS:
G is negative ( G < 0)
NON-SPONTANEOUS:
G is positive ( G > 0)
EQUILIBRIUM:



G=0
If a reaction is favorable for both enthalpy ( H < 0 ) and entropy ( S > 0),
then the reaction will be SPONTANEOUS ( G < 0 ) at any temperature.
If a reaction is unfavorable for both enthalpy ( H > 0 ) and entropy ( S < 0 ),
then the reaction will be NONSPONTANEOUS ( G > 0 ) at any temperature.
If a reaction is favorable for only one of either entropy or enthalpy, the standardstate free energy equation must be used to determine whether the reaction is
spontaneous or not.
Sample free energy calculation
Compound
NH4NO3(s)
Hf
-365.56
S
151.08
NH4+(aq)
-132.51
113.4
NO3-(aq)
-205.0
146.4
Calculate H , S , and G for the above reaction to determine whether
the reaction is spontaneous or not.
First let's calculate Hf . Note that in the above reaction, one mole of NH4NO3
dissociates in water to give one mole each of NH4+ and NO3-:
Next, let's calculate
S:
Lecture Notes
Information Sheet
Lecture Notes
Thermochem
More explaining
Independent practice
Name ………………………………………
Definitions quotes and
Diagrams
smart phrases
Title: entropy
KeyTeam
points……………………….
Equations
Date ………………………
When ΔS is positive and ΔH is negative, a process is spontaneous
When ΔS is positive and ΔH is positive, a process is spontaneous at high temperatures,
where exothermicity plays a small role in the balance.
When ΔS is negative and ΔH is negative, a process is spontaneous at low temperatures,
where exothermicity is important.
When ΔS is negative and ΔH is positive, a process is not spontaneous at any
temperature, but the reverse process is spontaneous.
Use the statements above to complete the column for ΔG
Complete the following table
Enter negative or Positive
ΔG
ΔH
Negative
Negative
Negative
Negative
Positive
Positive
T
High
low
High
Low
High
Low
ΔS
Negative
Negative
Positive
Positive
Negative
Negative
1. An Endothermic reaction may proceed spontaneously if there is an increase in
A. Potential Energy
B. Order
C. Concentration
D. Entropy
2. A reaction must be spontaneous if its occurrence is
A.exothermic with an decrease in entropy
B. exothermic with an increase in entropy
C. endothermic with an decrease in entropy
D. endothermic with an increase in entropy
3. Above 0oC, ice changes spontaneously to water according to the following equation:
H2O(s) + heat --> H2O(l)
The change in H2O(s) involve
A. an absorption of heat and a decrease in entropy
B. a release of heat and a decrease in entropy
C. an absorption of heat and a increase in entropy
D. a release of heat and a increase in entropy
4. A reaction must be spontaneous if the results in products that have
A. lower potential energy and less randomness
B. more potential energy and more randomness
C. lower potential energy and more randomness
D. more potential energy and less randomness
5. The change of the reactants into products will always be spontaneous if the products,
compared to the reactants, have
A. lower enthalpy and higher entropy
B. higher enthalpy and higher entropy
C. higher enthalpy and lower entropy
D. lower enthalpy and lower entropy
6. As a solid dissolves in water, the temperature of the water decrease. the dissolving of
this solid is
A. endothermic and spontaneous
B. endothermic and nonspontaneous
C. exothermic and nonspontaneous
D. exothermic and spontaneous
Consider the reaction below. What is ΔG0 at 341.4 K and will this reaction be productfavored spontaneously at this T?
CaCO3(s)  CaO(s) + CO2(g)
Thermodynamic values:
ΔHf0 (kJ/mol) S0 (kJ/Kmol)
CaCO3(s) -1206.9
+0.0929
CaO(s)
-635.1
+ 0.0398
CO2(g)
-393.5
+ 0.2136
Exit Ticket Clicker #
Name ……………………………………………
Team ……………………….
Title:Gibbs free energy
Date ………………………
Predict whether ΔS for each reaction would be greater than zero, less than zero, or too
close to zero to decide
CO(g) + 3 H2(g)  CH4(g) + H2O(g)
2 H2O(l)  2 H2(g) + O2(g)
I2(g) + Cl2(g)  2 ICl(g)
The ΔG of a chemical reaction refers to the change in
A. entropy
B. free energy
C. state
D. activation energy
Which of the following involves a decrease in entropy?
a. Natural gas burns.
b. A liquid freezes.
c. Dry ice sublimes.
d. Water evaporates.
A reaction is spontaneous if
a. enthalpy decreases and entropy increases.
b. enthalpy increases and entropy increases.
c. enthalpy decreases and entropy decreases.
d. enthalpy increases and entropy decreases.
HWK
Clicker #
Name …………………………………………
Team ……………………….
Title:Thermodynamics
Date ………………………
**
**
The temperature of a gas is proportional to the
A)
average velocity of the gas molecules.
B)
internal potential energy of the gas.
C)
number of gas molecules in a sample.
D)
average kinetic energy of the gas molecules.
The kinetic molecular theory explains the expansion of a solid material with increases of
temperature as basically the result of
A)
individual molecules expanding.
B)
increased translational kinetic energy.
C)
molecules moving a little farther apart.
D)
heat taking up the spaces between molecules.
Two degree intervals on the Celsius temperature scale are
A)
equivalent to 3.6 Fahrenheit degree intervals.
B)
equivalent to 35.6 Fahrenheit degree intervals.
C)
twice as hot as 1 Celsius degree.
D)
none of the above.
*
**
**
4
A temperature reading of 2°C is
A)
equivalent to 3.6°F.
B)
equivalent to 35.6°F.
C)
twice as hot as 1°C.
D)
none of the above.
5
The temperature known as room temperature is nearest to
A)
0°C.
B)
20°C.
C)
60°C.
D)
100°C.
6Using the absolute temperature scale, the freezing point of water is correctly written
as
A)
0 K.
B)
0°K.
C)
273 K.
D)
273°K.
*
7
The metric unit of heat called a calorie is
A)
the specific heat of water.
B)
the energy needed to increase the temperature of 1 gram of water 1 degree
Celsius.
C)
equivalent to a little over 4 joules of mechanical work.
D)
all of the above.
8
Which of the following is a shorthand way of stating that "the temperature change of a
substance is directly proportional to the quantity of heat added"?
A)
Q∝m
B)
m ∝ Tf - Ti
C)
Q ∝ ΔT
D)
Q = T f - Ti
9
The quantity known as specific heat is
A)
any temperature reported on the more specific absolute temperature scale.
B)
the energy needed to increase the temperature of 1 gram of a substance 1
degree Celsius.
C)
any temperature of a 1 kg sample reported in degrees Celsius.
D)
the heat needed to increase the temperature of 1 pound of water 1 degree
Fahrenheit.
13
When a solid, liquid, or a gas changes from one physical state to another, the change is
called
A)
melting.
B)
entropy.
C)
a phase change.
D)
sublimation.
6
As a solid undergoes a phase change to a liquid state, it
A)
releases heat while remaining at a constant temperature.
B)
absorbs heat while remaining at a constant temperature.
C)
releases heat as the temperature decreases.
D)
absorbs heat as the temperature increases
18