Sunday, July 10, 2011

Activity 8

1. Choose any Teaching Idea from any of the Chemistry Simulations (http://phet.colorado.edu/en/simulations/category/chemistry ) and post your results/data and/or answers on your blog.

CDE Standard 4 Benchmark 11, Grades 9-12. There are factors that may influence weather patterns and climate and their effects within ecosystems (for example: elevation, proximity to oceans, prevailing winds, fossil fuel burning, volcanic eruptions).

The Greenhouse Effect PhET Simulation Lesson

Learning Goals: Students will analyze how Greenhouse Gases affect Earth’s temperature and identify processes that might increase or decrease Earth’s temperature.


Ice Age
  1. Click on the “Ice Age” button and record the minimum temperature. 32F
  2. Record: CO2: 180ppm   CH4: .380ppm  N2O: .215ppm
  3. What happens to the sunlight photons as they hit the ground? They bounce back up toward the sky
  4. Are all of the sunlight photons being reflected back into space? Yes
  5. What happens to the temperature when you add clouds? Goes up.
  6. How are the photons affected by adding clouds?  If clouds are present they bounce of them.

Today
  1. Click on the “1750” button and record the minimum temperature. 60F
  2. Record: CO2: 388ppm   CH4: 1.843ppm  N2O: .317ppm
  3. What happens to the sunlight photons as they hit the ground? Absorbed into the ground.
  4. What happens to the temperature when you add clouds? Slightly increases
  5. How are the photons affected by adding clouds?  Some pass through and others bounce off.

1750
  1. Click on the “Today” button and record the minimum temperature. 55F
  2. Record: CO2: 280ppm   CH4: .730ppm  N2O: .270ppm
  3. What happens to the sunlight photons as they hit the ground? They are absorbed in the ground.
  4. What happens to the temperature when you add clouds? Stays about the same.
  5. How are the photons affected by adding clouds?  The sunlight photons bounce off but the infrared photons get through for the most part.

What would happen if there were no Greenhouse gases? Temperature would significantly drop

What would happen if Greenhouse gases increase? More fog and temperature would significantly increase.





2. Work with any of the Chemistry Simulations to create your own Teaching Idea.


http://phet.colorado.edu/en/simulation/soluble-salts

TABLE SALT
  1. Shake the salt shaker 3 times. How many total sodium and chloride molecules come out? Make an observation of this and draw a picture of what you see happening.
    1. Two of each
  2. Shake the salt shaker until there are 150 molecules total. Do they dissolve instantaneously?
    1. No
  3. What other uses besides salting food can you think of that involves table salt?

SLIGHTLY SOLUBLE SALTS
  1. What are some examples of Ions that are slightly soluble salts?
    1. Mercury(II) Bromide, Silver Bromide, Copper Iodine…
  2. Draw a picture of what 3 of the Ions listed above look like when you shake them into the water.
  3. Shake the salt shaker. What difference have occurred compared to that of table salt?        
    1. They take longer to dissolve. The ions are bound before they are dissolved.
  4. Where do the ions collect?
    1. At the bottom of the tank and along the sides.

C.4.2 Use the science content being learned to ask questions, plan investigations, make observations, make predictions, and offer explanations
C.4.6 Communicate the results of their investigations in ways their audiences will understand by using charts, graphs, drawings, written descriptions, and various other means, to display their answers
H.4.3 Show* how science has contributed to meeting personal needs, including hygiene, nutrition, exercise, safety, and health care

Activity 7

Complete the Teaching Idea “Concept Questions for Chemistry using PhET” posted by Trish Loeblein on the pH Scale simulation at PHET (http://phet.colorado.edu/en/simulation/ph-scale). On your blog post the answers with your scientific explanations from the “Clicker Questions pH Scale” posted by Trish.
 

1. There are 2 balloons in a room. They are identical in size and material. One balloon is filled with air and the other balloon is filled with Helium. How does the pressure of the air balloon compare to the pressure of the Helium balloon. The pressure in the air balloon is

Less
2. How does the pressure in the Helium balloon compare to the pressure of the air in the room? The pressure in the Helium balloon is 
Greater
3.  How do the number of air molecules in the air balloon  compare to the number of He atoms in Helium balloon? The number of air molecules is 
Less
4. How does the average speed of the Helium molecules compare to that of the air molecules?
The average speed of the He molecules is
Greater

5. What will happen to the pressure if temp is held constant and the volume is decreased?
Pressure goes up
 6. You are flying from Denver to Boston, and you bring along a ½ full bottle of shampoo that was well sealed before you left Denver. You land in Boston and proceed to your hotel. The number of air molecules within the shampoo bottle: 

Has increased


7.  If the walls of the shampoo bottle are strong and rigid so that the bottle has the same shape as before you left, how does the pressure of the air inside the bottle compare to the pressure of the air in Denver?

Greater than  

 

8.  How does the pressure inside the bottle compare to the pressure of the air in Boston?

Equal to


9. If you had a water bottle with very soft sides. When you open your suitcase in Boston, the bottle would look
Puffed Out


 
Complete the Teaching Idea “Intro to Strong and Weak Acids and Bases” posted by Chris Bires on the Acid-Base Solutions simulation (http://phet.colorado.edu/en/simulation/acid-base-solutions) and post on your blog your data and answers to the questions posed.




Strong Acid
Weak Acid
Strong Base
Weak Base
Water
pH meter read
(value)
2.00
4.50
12.00
9.50
7.00
pH paper
(color)
red
orange
navy
green
Light orange
Conductivity
(bright/dim/none)
Very bright
average
Very bright
bright
dim

Procedure:
This simulation allows you to change the concentration of a strong and weak acid and base.
Complete the table below for some strong acids and bases and weak acids and bases by adjusting the concentration.

Strong Acids

Strength
Initial Acid Concentration (mol/L)
[HA] (mol/L)
[A-] (mol/L)
[H+] (mol/L)
pH
.010 M
Neg
1.00x10-2
1.00x10-2
2
.050 M
Neg
5.00x10-2
5.00x10-2
1.3
.100 M
Neg
1.00x10-1
1.00x10-1
1
1.00 M
Neg
1.00x10 0
1.00x10 0
0

Weak Acids

Strength (approximately)
Initial Acid Concentration (mol/L)
[HA] (mol/L)
[A-] (mol/L)
[H+] (mol/L)
pH
.015 M
1.49x10-2
7.29x10-5
7.29x10-5
4.14
.150 M
1.50x10-1
2.31x10-4
2.31x10-4
3.64
.150 M
1.85x10-2
1.32x10-1
1.32x10-1
.88
.015 M
2.33x10-4
1.48x10-2
1.48x10-2
1.83

Strong Bases

Strength
Initial Acid Concentration (mol/L)
[MOH] (mol/L)
[M+] (mol/L)
[OH-] (mol/L)
pH
.010 M
Neg
1.00x10-2
1.00x10-2
12
.050 M
Neg
5.00x10-2
5.00x10-2
12.7
.100 M
Neg
1.00x10-1
1.00x10-1
13
1.00 M
Neg
1.00x10 0
1.00x10 0
14

Weak Bases

Strength (approximately)
Initial Acid Concentration (mol/L)
[B] (mol/L)
[BH+] (mol/L)
[OH-] (mol/L)
pH
.015 M
1.50x10-2
4.20x10-5
4.20x10-5
9.62
.150 M
1.50x10-1
1.33x10-4
1.33x10-4
10.12
.015 M
1.64x10-4
1.48x10-2
1.48x10-2
12.17
.150 M
1.38x10-2
1.36x10-1
1.36x10-1
13.13

Conclusion Questions:
1.      A strong acid is very concentrated.
2.      A weak base is a weak electrolyte.
3.      A strong base is a strong electrolyte.
4.      At the same concentration (Molarity) a strong acid will have a lower.
5.      As concentration of a weak acid increases, the pH decreases.
6.      As concentration of a weak base increases, the pH increases.
7.      As the concentration of a weak acid increases, the number of ions increases.
8.      As the concentration of a weak acid increases, conductivity increases.
9.      As the strength of a weak acid increases, the proportion of ions to molecules decreases.
10.  As the strength of a weak acid increases, the conductivity increases / decreases / remains constant.
11.  What are the pH values of a weak acid with a concentration of 0.10 and a strong acid with a concentration of 0.01, ten times lower?     Weak acid, 0.10 M : 4 Strong Acid, 0.01 M : 2