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 correct answer would be false. The solution in the middle is a neutral solution. The solution to the right is a base and the solution to the left is an acid.
2) The correct answer would be more than one.
3) The correct answer would be C. Looking at the pH scale for picture C, you can see that it is 2. On our pH scale 2 is a very acidic.
4) B would be a basic solution. It has a pH of 13 on the pH scale.
5) The correct answer is more than one of the solutions is acidic. A and B both have pHs of 5 and 2.5 which based on the pH scale shows that it is acidic.
6) Adding water will INCREASE the pH. The pH will increase due to the fact that adding water will lower the acidity.
7) The pH will decrease. Adding more water will lower the bascicity of the solution.
8) The order from most basic to most acidic would be A,B,C.
9) The order from most acidic to most basic would be B,A,C.
10) The correct answer would be that something was added that made the equilibrium shift left.
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) | 2.00 | 4.50 | 12.00 | 9.50 | 7.00 |
pH paper (color) | Red | Orange | Blue | Green | Orange |
Conductivity (bright/dim/none) | Bright | Dim | Bright | Dim | None |
Exists as Mostly (ions/molecules) | Ions | Ions | Ions | Ions | Molecules |
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 | negligible | 1.00 x 10^ -2 | 1.00 x 10^ -2 | 2.00 |
| .050 M | negligible | 5.00 x 10^ -2 | 5.00 x 10^ -2 | 1.30 |
| .100 M | negligible | 1.00 x 10 ^ -1 | 1.00 x 10 ^ -1 | 1.00 |
| 1.00 M | negligible | 1.00 x 10^ 0 | 1.00 x 10^ 0 | 0.00 |
Weak Acids
Strength (approximately) | Initial Acid Concentration (mol/L) | [HA] (mol/L) | [A-] (mol/L) | [H+] (mol/L) | pH |
 | .015 M | 1.49 x 10^ -2 | 5.10 x 10^ -5 | 5.10 x 10^ -5 | 4.29 |
| .150 M | 1.50 x 10^ -1 | 1.61 x 10^ -4 | 1.61 x 10^ -4 | 3.79 |
 | .015 M | 1.36 x 10^ -4 | 1.49 x 10^ -2 | 1.49 x 10^ -2 | 1.83 |
| .150 M | 1.17 x 10^ -2 | 1.38 x 10^ -1 | 1.38 x 10^ -1 | .86 |
Strong Bases
Strength | Initial Acid Concentration (mol/L) | [MOH] (mol/L) | [M+] (mol/L) | [OH-] (mol/L) | pH |
| .010 M | Negligible | 1.00 x 10^ -2 | 1.00 x 10^ -2 | 12.00 |
| .050 M | Negligible | 5.00 x 10^ -2 | 5.00 x 10^ -2 | 12.70 |
| .100 M | Negligible | 1.00 x 10^ -1 | 1.00 x 10^ -1 | 13.00 |
| 1.00 M | Negligible | 1.00 x 10^ 0 | 1.00 x 10^ 0 | 14.00 |
Weak Bases
Strength (approximately) | Initial Acid Concentration (mol/L) | [B] (mol/L) | [BH+] (mol/L) | [OH-] (mol/L) | pH |
| .015 M | 1.50 x 10^ -2 | 1.84 x 10^ -5 | 1.84 x 10^ -5 | 9.26 |
| .150 M | 1.50 x 10^ -1 | 5.81 x 10^ -5 | 5.81 x 10^ -5 | 9.76 |
 | .015 M | 3.38 x 10^ -4 | 1.47 x 10^ -2 | 1.47 x 10^ -2 | 12.17 |
| .150 M | 2.47 x 10^ -2 | 1.23 x 10^ -1 | 1.23 x 10^ -1 | 13.10 |
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 :____1.06________ Strong Acid, 0.01 M :____2.00________
12. Explain the significance of the results of your calculation above. A weaker pH indicates a stronger acid whereas a higher pH indicates a weaker acid.
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