Strengths of Acids
Arrhenius & Bronsted-Lowry definition:
gives H+, hydronium ions in solution
• Strong acids break down • Weak acids do NOT
100% in solution
break down completely
– HCl hydrochloric acid
– HNO3 nitric acid
– HBr hydrobromic acid
HCl
H+ Cl- H+
+
Cl- H ClCl- H+
More
break
down =
stronger
acid
H2S
H+
S-2
H2S H S
2
Strong vs Weak
• Strong will light a bulb
brightly!
• Weak will make the
bulb light dimly.
Strong Bases
Arrhenius definition = donates OHBronsted-Lowry definition = accepts H+
Strength is determined the same way as acids
More break down = stronger base
• Strong bases break
down 100% in
solution
–
–
–
–
KOH
Ba(OH)2
CsOH
NaOH
• Weak bases do not
break down
completely
– Ca(OH)2
– LiOH
– RbOH
Battery Acid & HF
Stomach acid, HCL
pH Scale
Lemon juice, vinegar
• pH = power of
hydrogen
Tomato juice, acid rain
• pH = -log [H+]
Black coffee
Urine, saliva
• Each time you change
PURE water
a number on the scale
Salt water
you change by a factor
Baking soda
of 10
orange juice,
Great Salt Lake
Ammonia
Soapy Water
Bleach
Liquid Drain Cleaner
– pH of 3 is 10 times less
acidic as pH of 2
– pH of 1 is 100 times
more acidic as pH 3
Neutralization
• Acid + Base  Salt + H2O
– A salt is a metal and non-metal (not just NaCl)
• HCl + NaOH  NaCl + H2O
• HCl + Ca(OH)2  CaCl2 + H2O
Titrations
• Technique used by chemists to determine an
unknown molarity of a substance
• We can use an indicator (changes color) to tell
us when we are neutral (moles of acid = moles
of base)
link
Titration Calculations
Moles of Acid = Moles of Base
M1V1=M2V2
Titration Problems
acid = base
M1V1= M2V2
1. What is the molarity of a CsOH solution if
30.0mL of the solution is neutralized by
26.4 mL of a 0.250 M HBr solution?
Titration Problems
acid = base
M1V1= M2V2
2. What is the molarity of a nitric acid if
43.33 mL 0.100 M KOH solution is needed
to neutralize 20.0mL of HNO3?
Titration Problems
acid = base
M1V1= M2V2
3. What is the concentration of a household
ammonia cleaning solution if 49.9 mL
0.59 M HCl is required to neutralize
25.00 mL solution?
Titration Problems
acid = base
M1V1= M2V2
4. What is the molarity of an NaOH solution
if 50 mL of the solution is neutralized by
37 mL of 0.5 M HCl?