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Acids and Bases. Definitions. Arrhenius Acid is an H+ donor Base is an OH- donor Bronsted-Lowrey Acid is an H+ donor Base is an H+ receptor Lewis Acid is an electron pair acceptor Base is an electron pair donor. pH. Measures acidity = -log [H+] 7 is neutral
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Definitions • Arrhenius • Acid is an H+ donor • Base is an OH- donor • Bronsted-Lowrey • Acid is an H+ donor • Base is an H+ receptor • Lewis • Acid is an electron pair acceptor • Base is an electron pair donor
pH • Measures acidity • = -log [H+] • 7 is neutral • Below 7 is acid, above 7 is base • Close to 7 is weaker, farther away from 7 is stronger • [H+] = inv log (-pH) • pH + pOH = 14
Common names • Vinegar Acetic acid • Battery acid Sulfuric acid • Muriatic acid HCl • Stomach acid HCl • Aqua regia HCl + HNO3 • Aspirin Acetylsalicylic acid
Normality • Equivalents / Liter of solution • Typically, M x subscript of H or OH = N • Need to use normality in titration equation
Acid strength • Refers to percent dissociation • Measured by Ka
Classification • Oxy acids • H + an oxygen containing polyatomic anion • Binary acids • H + a monoatomic anion • OR • H+ a non oxygenated polyatomic anion (ie, CN-)
Oxy acids • To name: • Name the associated polyatomic anion • Replace –ate with –ic acid • Replace –ite with –ous acid • To write the formula • Replace the –ic with -ate and write the polyatomic anion OR • Replace the –ous with –ite and write the polyatomic anion • Balance your charge out with hydrogen
Examples • HNO3 • H2SO4 • H2CO3 • HNO2 • H3PO4 • H2CrO4 • H2Cr2O7
Binary acids: no oxygen • To name: • Prefix is hydro • Name anion with –ic acid ending • To write the formula: • Write the H • Write the anion formula or symbol • Balance you charge with the subscripts if necessary
Examples • HCl • HF • H2S • HCN • HI
Give names or formulas • HNO3 • HCl • H2SO4 • Carbonic acid • Nitrous acid • Chromic acid • Hydrocyanic acid
Answers • HNO3 Nitric acid • HCl Hydrochloric acid • H2SO4 Sulfuric acid • Carbonic acid H2CO3 • Nitrous acid HNO2 • Chromic acid H2CrO4 • Hydrocyanic acid HCN
pOH and pH • pH + pOH always equals 14 • This is because the autoionization of water results in a H+ of 1x10-7 and an OH- of 1x10-7 • Example: if the pH = 7.5, what is the pOH?
Answer • If the pH = 7.5, what is the pOH? pH + pOH = 14 7.5 + pOH = 14 pOH = 14-7.5 pOH = 6.5
Neutralization HCl + NaOH NaCl + HOH You take the H from the acid and combine it with the OH from the base. That makes water. What’s left is called a salt.
Titration • NA X VA = NB X VB
Sample problem • How many mL of 2.0 N HCl are required to neutralize 30 mL of 3.7 N NaOH? • NA X VA = NB X VB • (2.0N)(VA) = (3.7N)(30mL) • Divide both sides by 2.0N • VA = 55.5mL