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”

Reactions involving weak bases HCl(aq) + NH3(aq)  NH4+(aq) + Cl-(aq) Net-Ionic Equation:

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:

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:

Solution Concentration: Molarity Molarity = moles solute per liter of solution 0.30 mol NH3 dissolved in 0.500 L Concentration = Written like: [NH3] = 0.60 M If you dissolve 0.32 mol NH3 to make 750 mL of solution, what is [NH3]?

pH: Quantitative Measure of Acidity Acidity is related to concentration of H+ (or H3O+) pH = -log[H+]

pH Scale In pure water, a few molecules ionize to form H3O+ and OH– H2O + H2O  OH– + H3O+ In acidic and basic solutions, these concentrations are not equal acidic: [H3O+] > [OH–] basic: [OH–] > [H3O+] neutral: [H3O+] = [OH–]

pH Scale Measure how much H3O+ is in a solution using pH pH < 7.0 = acidic pH > 7.0 = basic pH = 7.0 = neutral Measure of H3O+ and OH– concentration (moles per liter) in a solution As acidity increases, pH ?

pH Scale The pH scale is logarithmic: 100 102 log(102) = 2 10 101 log(101) = 1 1 100 log(100) = 0 0.1 10–1 log(10–1) = –1 0.01 10–2 log(10–2) = –2 pH = –log [H+]

pH Scale pH = –log [H3O+] What is the pH if [H+] = 1 x 10–5? Acidic or basic? What is the pH if [H+] = 1 x 10–9? Acidic or basic? What is the pH if [H+] = 0.000057 M?

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?

Finding [H3O+] from pH [H+] = 10-pH What is [H+] if pH = 8.9?