Acid-base indicators change color based on pH, acting as weak acids or bases. Common indicators and their colors in acidic versus basic conditions are listed. Neutralization occurs when an acid and base react to form water and a salt, involving the combination of H+ and OH- ions. The pH of solutions formed from strong acid-strong base neutralization will be 7, while strong acid-weak base solutions will be less than 7 and strong base-weak acid will be greater than 7.

1. By: Alyssa Aira D. Aquino

2. Acid-Base
Indicators
also known as pH
indicators are
substances which
change color with
pH.

3. An indicator is
usually some weak
organic acid or base
dye that changes
colors at definite
pH values.

4. The weak acid form
(Hin) will have one
color and the
negative ion (In-)
will have different
colors.

5. Indicator Color (Acid) Color (Base)
Thymol Blue-
1st Change
Red Yellow
Methyl Orange Red Yellow
Bromoscresol
Green
Yellow Blue
Methyl Red Yellow Red

6. Example of
Acid-Base
Indicators or
pH indicators:

7. Indicator Color (Acid) Color (Base)
Bromothymol
Blue
Yellow Blue
Phenol Red Yellow Red
Thymol Blue-
2nd Change
Yellow Blue
Litmus Paper Red Blue

8. By: Alyssa Aira D. Aquino

9. Neutralization
reacts when an
acid and a base
react to form
water and a salt.

10. It involves the
combination of
H+ ions and OH-
ions to generate
water.

11. N parts of acids
will always
neutralize N
parts of base.

12. Determining
what is Strong
acid or Strong
base:

13. Strong Acids Strong Bases
HCl LiOH
HBr NaOH
HI KOH
HCIO4 RbOH
HNO3 CsOH
Ca(OH)2
Sr(OH)2
Ba(OH)2
List of Strong Acids and
Bases:

14. Strong Acid-Strong Base
Neutralization
HCl(aq)acid+NaOH(aq)base⇋N
aCl(aq)salt+H2O(l)waterHCl(aq)
acid+NaOH(aq)base⇋NaCl(aq)s
alt+H2O(l)water

15. When the spectator ions are removed,
the net ionic equation shows
the H+H+ and OH−OH− ions forming
water in a strong acid, strong base
reaction:
H+(aq)+OH−(aq)⇋H2O(l)H(aq)++OH(
aq)−⇋H2O(l)

16. When a strong acid
neutralizes a strong
base, the pH of the
salt solution will
always be 7.

17. Weak Acid-Weak Base Neutralization
A weak acid, weak base reaction can
be shown by the net ionic equation
example:
H+(aq)+NH3(aq)⇋NH+4(aq)H(aq)
++NH3(aq)⇋NH4(aq)+

18. When a strong acid
neutralizes a weak
base, the resulting
solution's pH will
be less than 7.

19. When a strong base
neutralizes a weak
acid, the resulting
solution's pH will
be greater than 7

20. Strength of Acid and Base pH Level
Strong Acid-Strong Base 7
Strong Acid-Weak Base <7
Weak Acid-Strong Base >7
Weak Acid-Weak Base pH <7 if Ka>KbKa>Kb
pH =7 if Ka=KbKa=Kb
pH >7 if Ka<KbKa<Kb