Activity 7

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. B. the color does not tell if it is an acid or a base it is the pH scale level.
2. D. Because both b and c are above 7 so they are both considered to be basic.
3. C because it has a higher level of Hydrogen atoms compared to the others.  
4. B because the hydrogen atoms powers need to be over 7, and example B has -13 while the others have less than 7.
5. D. because there are two solutions that are under 7. A has a pH scale level of 5 and B has a pH scale  level of 2.5
6. A. because when you add water it lessens the acidity which it turn will increase the pH level
7. B. because when you add water it lessens the basicity so that will drop the pH scale number down.
8. A,   because the closer the number is to zero the more acid it is. So 6.5 then 7.4 and then 12.06 is the closest to 14 so that is the more basic.
9. C because looking at the powers that the numbers have they are increasing.
10. A. because something was added to the spit to make it increase.

 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	4.50	12	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	molecules	molecules	ions

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	1.00x (10`-2)	55.6	2.00
	.050 M	negligible	5.00x(10`-2)	55.6	1.30
	.100 M	negligible	1.00x (10`-1)	55.5	1.00
	1.00 M	negligible	1.00x(10`0)	54.6	0.00

Weak Acids

Strength (approximately)	Initial Acid Concentration (mol/L)	[HA] (mol/L)	[A-] (mol/L)	[H+] (mol/L)	pH
	.015 M	1.5 x (10`-2)	2.94 x (10`-5)	55.6	4.53
	.150 M	1.50x (10`-1)	1.10x (10`-4)	55.6	3.96
	.015 M	1.36x (10`-4)	1.40x (10`-2)	55.6	1.83
	.150 M	1.17x (10`-2)	1.38x (10`-1)	55.5	.86

Strong Bases

Strength	Initial Acid Concentration (mol/L)	[MOH] (mol/L)	[M+] (mol/L)	[OH-] (mol/L)	pH
	.010 M	negligible	1.00x (10`-2)	1.00x (10`-2)	12.00
	.050 M	negligible	5.00x (10`-2)	5.00x (10`-2)	12.70
	.100 M	negligible	1.00x (10`-1)	1.00x (10`-1)	13.00
	1.00 M	negligible	1.00x (10`0)	1.00x (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	1.50x (10`-2)	3.46x (10`-5)	3.46x (10`-5)	9.54
	.150 M	1.50x (10`-1)	1.10x (10`-4)	1.10x (10`-4)	10.04
	.015 M	6.49x (10`-5)	1.49x (10`-2)	1.49x (10`-2)	12.17
	.150 M	6.03x (10`-3)	1.44x (10`-1)	1.44x (10`-1)	13.16

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 :__9.68______           Strong Acid, 0.01 M :2.00_______

12.   Explain the significance of the results of your calculation above. ____that the concentration  of an acid can really change the pH scale. _________