Acids and Bases

Activity 7

 

2. Here are the answers to "Concept questions for Chemistry" by Trish Loeblein

• 1. B, the color of a solution is not an accurate indication of an acid or base. It depends on where the solution ranks on the pH scale and what color the litmus paper turns.
• 2. D, the pH level of B and C is above 7 which makes both solutions basic.
• 3. C, the solution has a much higher number of hydrogen atoms as indicated by their red color.
• 4. B, the number of hydrogen atoms is a lot lower than the amount of hydroxide in solution B which makes it a base.
• 5. D, both A and B are acidic solutions because the number of hydrogen molecules outnumbers the amount of hydroxide which makes both of them acids.
• 6. A, since the pH of the solution is 5 which makes it an acid, then adding water will make the solution less acidic or increase the pH. Adding water to a solution brings the pH level closer to 7, so the pH level could increase or decrease depending on the beginning pH level.
• 7. B, like I said in the previous question, adding water to a solution brings the pH level closer to 7. In this situation, the solution was basic so the pH level will decrease when water is added.
• 8. A, the closer a solution is to having a pH of 0 then the more acidic a solution is. In this case, 6.5 was the most acidic solution followed by 7.4 and 12.06.
• 9. E, when ordering from most acidic to most basic, I think that C is the most acidic solution because it has the highest amount of hydrogen atoms. It also has more hydrogen atoms than hydroxide which makes it an acid. A is the next most acidic solution with an equal amount of hydrogen and hydroxide molecules, and B is the most basic because the amount of hydroxide greatly outnumbers the hydrogen.
• 10. A, spit has a pH of 7.4 while water has a constant pH of 7. This means that something must be added to spit to make it more basic. In order for the water equilibrium to exist, something was added to the spit to make the equilibrium (pH level of 7) shift left.

 

 

3. "Intro to Strong and Weak Acids and Bases"

 

	Strong Acid	Weak Acid	Strong Base	Weak Base	Water
pH meter read (value)	1	5	13	9	7
pH paper (color)	red	orange	Dark blue	green	yellow
Conductivity (bright/dim/none)	Bright	Dim	Bright	Dim	None
Exists as Mostly (ions/molecules)	Ions	Ions	Molecules	Molecules	Ions

Strong Acids

Strength	Initial Acid Concentration (mol/L)	[HA] (mol/L)	[A-] (mol/L)	[H+] (mol/L)	pH
|	.010 M	Negligible	0.01	55.6	2
|	.050 M	Negligible	0.05	55.6	1.3
|	.100 M	negligible	0.1	55.5	1
|	1.00 M	Negligible	1	54.6	0

Weak Acids

Strength (approximately)	Initial Acid Concentration (mol/L)	[HA] (mol/L)	[A-] (mol/L)	[H+] (mol/L)	pH
|	.015 M	0.015	0.00003	55.6	4.6
|	.150 M	0.15	0.00011	55.6	4
|	.015 M	0.000014	0.014	55.6	2
|	.150 M	0.0115	0.135	55.5	0.8

Strong Bases

Strength	Initial Acid Concentration (mol/L)	[MOH] (mol/L)	[M+] (mol/L)	[OH-] (mol/L)	pH
|	.010 M	Negligible	0.01	0.01	12
|	.050 M	Negligible	0.05	0.05	12.7
|	.100 M	Negligible	0.1	0.1	13
|	1.00 M	Negligible	1	1	14

Weak Bases

Strength (approximately)	Initial Acid Concentration (mol/L)	[B] (mol/L)	[BH+] (mol/L)	[OH-] (mol/L)	pH
|	.015 M	0.015	0.000035	0.000035	9.6
|	.150 M	0.15	0.0001	0.0001	10
|	.015 M	0.000065	0.015	0.015	12.2
|	.150 M	0.006	0.14	0.14	13.1

Conclusion Questions