The relationship between pH
and hydrogen ion
concentration
The Relationship Between pH and Hydrogen Ion Concentration
“Acidic”
Higher [H+]
Hydrogen ion
concentration:
pH:
10-1 M
1
“Neutral”
“Basic”
Lower [H+]
10-7 M
7
This slide emphasizes the following points:
• Acidic solutions have a relatively high [H+]
• As pH increases, [H+] decreases
10-14 M
14
Sample question 1
+
+ H
H+H + H+
+
H+ HH+ HH+ + HH
H+
H++H+
+
+
+ H
H
H
+
+
HH+
H H+
+
+
H
H+ HH+ HH+ +
H+ H+ HH+ + H+
HH+ +H+ H+ +
+
HH+
H+H
+
+ +H
+
+
H+H H+H+ HH
H++ + H +
H
H
H+H+H+ H
H++ + HHH+
H
+
+
+
+
H HH H H+ H++H+
+ H+H+
H+HH+ +H++H
+
H
H
+
+
+
+
HH+ H HH+ H
+
H
+
+
+
+
+
HH+H
H
H+ H+
H+H
H
HH+ + H+ H+
+
H
+
+
H HHH++ H+HH+ + H+
HH+ +H+H++H+ H++
H+ +HH+
H+H+H+H
H
H+
H+
H+
H+
H+
H+
H+
H+
B
C
A
Which of the following lists the above solutions in order
of increasing hydrogen ion concentration?
I.  B, A, C
II.  C, A, B
III.  A, B, C
Answer to sample question 1
H+
H+
H+
H+
H+
H+
C
H+
H+
+
+ H
H+H + H+
+
H+ HH+ HH+ + HH
+
H+
H+H+
+
+
+ H
H
HH+H+
H+ H+
+
+
H
H+ HH+ HH+ +
H+ H+ HH+ + H+
HH+ +H+ H+ +
+
HH+
H+H
A
+
+ +H
+
+
H+H H+H+ HH
H++ + H +
H
H
H+H+H+ H
H++ + HHH+
H
+
+
+
+
H HH H H+ H++H+
+ H+H+
H+HH+ +H++H
+
H
H
+
+
+
+
HH+ H HH+ H
+
H
+
+
+
+
+
HH+H
H
H+ H+
H+H
H
HH+ + H+ H+
+
H
+
+
H HHH++ H+HH+ + H+
HH+ +H+H++H+ H++
H+ +HH+
H+H+H+H
H
B
Which of the following lists the above solutions in order of
increasing hydrogen ion concentration?
I. 
B, A, C
II.  C, A, B is the correct answer as shown above
III.  A, B, C
Sample question 2
+
+ H
H+H + H+
+
H+ HH+ HH+ + HH
H+
H++H+
+
+
+ H
H
H
+
+
HH+
H H+
+
+
H
H+ HH+ HH+ +
H+ H+ HH+ + H+
HH+ +H+ H+ +
+
HH+
H+H
+
+ +H
+
+
H+H H+H+ HH
H++ + H +
H
H
H+H+H+ H
H++ + HHH+
H
+
+
+
+
H HH H H+ H++H+
+ H+H+
H+HH+ +H++H
+
H
H
+
+
+
+
HH+ H HH+ H
+
H
+
+
+
+
+
HH+H
H
H+ H+
H+H
H
HH+ + H+ H+
+
H
+
+
H HHH++ H+HH+ + H+
HH+ +H+H++H+ H++
H+ +HH+
H+H+H+H
H
H+
H+
H+
H+
H+
H+
H+
H+
B
C
A
Which of the following lists the above solutions in order
of increasing pH?
I.  B, A, C
II.  C, A, B
III.  A, B, C
Answer to sample question 2
+
+ +H
+ H+
H+H H+H+ HH
++
H
+
+
H+HH+H+ H
H
H++ + HHH+
H
+
H+HH+ +H+H+ H+H+
+ H+H+
H+HH+ +H++H
+
+
HH+ + H+HHH
H+ + H
+
+H+ H
++ H
HH+ +H
H
+
+
H HH+H+ H+HH+ +
+
H
+ ++ H+HH
+ + H+
H+ HH
H
HH+ +H+H++H+ H++
H+ +HH+
H+H+H+H
H
B
+
+ H
H+H + H+
+
H+ HH+ HH+ + HH
+
H+
H+H+
+
+
+ H
H
HH+H+
H+ H+
+
+
H
H+ HH+ HH+ +
H+ H+ HH+ + H+
HH+ +H+ H+ +
+
HH+
H+H
A
H+
H+
H+
H+
H+
H+
H+
H+
C
Which of the following lists the above solutions in order of increasing
pH?
I.  B, A, C is the correct answer as shown above. Note that
the higher the hydrogen ion concentration, the lower
the pH!!!!
II.  C, A, B
III.  A, B, C