2. 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. The color of a solution identifies if it is an acid, base, or neutral solution
A.True B. False C. Pink are base and clear are acid
B Show sim: the left is milk, then blood, then a custom liquid like NaOH
D (B and C) A milk, B blood C. custom at pH =12
A, B, C, D(More than one, or E(Difficult to tell)
C, but they may argue E A. Custom pH =13 B. water pH =7 C. vomit pH=2
A, B, C, D(more than one), or E(None)
B A. Water pH =7 B. pH =13 C. soda pop pH =2.5
5. Which solution is acidic?
A, B, C, D(more than one), or E(None)
D (A and B) A. Coffee pH =5 B. soda pop pH =2.5 C. custom pH =13
6. How will adding water effect the pH?
A.Increase the pH, B.Decrease the pH, or C.No pH change
A more water lessens the acidity, so pH goes up
7. How will equal amount of water effect the pH?
A.Increase the pH, B.Decrease the pH, C.The pH will be cut in half, D.No pH change
B: more water lessens the basicity , so pH goes down, but not by 2 (log scale)
A.A B C, B.A C B, C.B A C, D.C B A, or E.C A B
A: A milk, B blood C. custom at pH =12
9. What is the order from most acidic to most basic?
A.A B C, B.A C B, C.B A C, D.C B A, or E.C A B
C A. Water pH =7 B. pH =13 C. soda pop pH =2.5
10. If spit has a pH = 7.4, what does that tell you about the water equilibrium?
2H2O « OH- + H3O+
A.Something was added that made the equilibrium shift left
B.Something was added that made the equilibrium shift right
C.pH has nothing to do with the water equilibrium
A: Since the pH is not 7, then something was added to make the equilibrium shift left. For example, if NaOH was added to water, OH- is immediately in the solution and some of it will react with the H3O+ , so the pH (which is inversely related to [H3O+ ]), goes up.
If something like HCl were added there would be more H3O+ , which would also cause a shift left, but there would be less OH- , (which is directly related to pH), so the pH is less than 7.
3. 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 | 4.5 | 12 | 9.5 | 7 |
pH paper (color) | Red 2 | Orange 4 | Blue 13 | Grey 9 | Yellow 7 |
Conductivity (bright/dim/none) | Bright | Dim | Bright | Dim | None |
Exists as Mostly (ions/molecules) | Molecules | Molecules | Molecules | Molecules | Molecules |
Strong Acids
Strength | Initial Acid Concentration (mol/L) | [HA] (mol/L) | [A-] (mol/L) | [H+] (mol/L) | pH |
 | .010 M | negligible | 100x10-2 | 100x10-2 | 2 |
| .050 M | negligible | 5.00x10-2 | 5.00x10-2 | 1.3 |
| .100 M | negligible | 1.00x10-1 | 1.00x10-1 | 1 |
| 1.00 M | negligible | 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 | 1.54x10-2 | 3.92x10-5 | 3.92x10-5 | 4.41 |
| .150 M | 1.50x10-1 | 1.22x10-4 | 1.22x10-4 | 3.91 |
 | .015 M | 1.51x10-4 | 1.48x10-2 | 1.48x10-2 | 1.83 |
| .150 M | 1.29x10-2 | 1.37x10-1 | 1.37x10-1 | .86 |
Strong Bases
Strength | Initial Acid Concentration (mol/L) | [MOH] (mol/L) | [M+] (mol/L) | [OH-] (mol/L) | pH |
| .010 M | negligible | 1.00x10-2 | 1.00x10-2 | 12 |
| .050 M | negligible | 5.00x10-2 | 5.00x10-2 | 12.70 |
| .100 M | negligible | 1.00x10-1 | 1.00x10-1 | 13 |
| 1.00 M | negligible | 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 | 3.87x10-5 | 3.87x10-5 | 9.59 |
| .150 M | 1.50x10-1 | 1.22x10-4 | 1.22x10-4 | 10.09 |
| .015 M | 1.51x10-4 | 1.48x10-2 | 1.48x10-2 | 12.17 |
| .150 M | 1.29x10-2 | 1.37x10-1 | 1.37x10-1 | 13.14 |
Conclusion Questions:
1. A strong acid is very concentrated / exists primarily as ions. (circle)
2. A weak base is a nonelectrolyte / weak electrolyte / strong electrolyte.
3. A strong base is a nonelectrolyte / weak electrolyte / strong electrolyte.
4. At the same concentration (Molarity) a strong acid will have a higher / lower / the same pH as a weak acid.
5. As concentration of a weak acid increases, the pH increases / decreases / remains constant.
6. As concentration of a weak base increases, the pH increases / decreases / remains constant.
7. As the concentration of a weak acid increases, the number of ions increases / decreases / remains constant.
8. As the concentration of a weak acid increases, conductivity increases / decreases / remains constant.
9. As the strength of a weak acid increases, the proportion of ions to molecules increases / 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 : 4.35 Strong Acid, 0.01 M : 1.00
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