Net Ionic Equations

1
Net Ionic Equations

• HCl(aq) NaOH(aq) ? NaCl(aq) H2O(l)
• What really happens
• H(aq) OH-(aq) ? H2O(l)
• Sodium ion and chloride ion are spectator ions

2
Reactions involving weak bases

• HCl(aq) NH3(aq) ? NH4(aq) Cl-(aq)
• Net-Ionic Equation

3
What are the products CH3CO2H(aq) NaOH(aq)
?

• 1. CH3CO2H2(aq) NaO(aq)
• 2. CH3CO2-(aq) H2O(l) Na(aq)
• 3. CH4(g) CO2(g) H2O(l)

Net-Ionic Equation
4
What are the products HCN(aq) NH3(aq)
?

• 1. NH4(aq) CN-(aq)
• 2. H2CN(aq) NH2-(aq)
• 3. C2N2(s) 3 H2(g)
• Net-ionic equation

5
Solution Concentration Molarity

• Molarity moles solute per liter of solution
• 0.30 mol NH3 dissolved in 0.500 LConcentration
  
• Written like NH3
  0.60 M
• If you dissolve 0.32 mol NH3 to make 750 mL of
  solution, what is NH3?

6
pH Quantitative Measure of Acidity

• Acidity is related to concentration of H (or
  H3O)
• pH -logH H 10-pH

7
pH Scale

• In pure water, a few molecules ionize to form
  H3O and OHH2O H2O ? OH H3O
• In acidic and basic solutions, these
  concentrations are not equalacidic H3O gt
  OHbasic OH gt H3Oneutral H3O
  OH

8
pH Scale

• Measure how much H3O is in a solution using pH
• pH lt 7.0 acidic
• pH gt 7.0 basic
• pH 7.0 neutral
• Measure of H3O and OH concentration (moles per
  liter) in a solution
• As acidity increases, pH ?

9
pH Scale

• The pH scale is logarithmic100 102 log(102)
  210 101 log(101) 11 100 log(100)
  00.1 101 log(101) 10.01 102 log(102)
  2
• pH log H

10
pH Scale

• pH log H3O
• What is the pH if H 1 x 105? Acidic or
  basic?
• What is the pH if H 1 x 109? Acidic or
  basic?
• What is the pH if H 0.000057 M?

11
pH of Strong Acid Solutions
For monoprotic strong acids H acid What
is the pH of a 2.4 x 10-2 M solution of HNO3?
12
Finding H3O from pH

• H 10-pH
• What is H if pH 8.9?

13
What is the possible range of pH values?