Chem178 Ch 16 and 17 – Flashcards
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What is the pH of a 0.015 M aqueous solution of barium hydroxide, Ba(OH)2
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pOH = -log (0.015 × 2) = 1.52
pH = 14.00 - pOH = 12.48
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Which of the following ions will act as a weak base in water?
OH? Cl? NO3? ClO-
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ClO-
ClO- is the conjugate base of a weak acid, HClO
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NH4 and NH3 which is acid which is base
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NH4 acid
NH3 base
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pKa for a strong acid
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really small number
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when a substance is both a Brønsted-Lowry acid and a Brønsted-Lowry base it undergoes
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autoionization/autoprotolysis:
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What are the relationships between Ka, Kb, Kw, pKa , pKb, and pKw
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Ka • Kb = KW
pKa + pKb = pKW
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For each of the following pairs, write the stronger base and its conjugate acid.
NO3 or NO2
H or OH
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H and H2
NO2 and HNO2
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The conjugate base of HSO3- is
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SO3 2-
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Araange in order of increasing strength HBrO HClO HIO HIO3 HCl
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HIO < HBrO < HClO < HClO2 < HIO3
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predict whether the following equilibrium reactions lie predominately to the left
HPO4+ H2O ---> H2PO4- + OH-
NH4+ + OH- ---> NH3+ H2O
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H2O is a weaker acid than H2PO4-: equilibrium lies to the left
NH4+ is a stronger acid than H2O : equilibrium lies to the right
(compare to water, whichever side is weaker is where equilibrium lies)
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when OH- = H+ what are their concentrations?
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1x10-7 because when multiplied they equal 10-14
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What is the H+ concentration for an aqueous solution with pOH = 3.14 at 25 ?C?
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1.4×10?11 M
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At a certain temperature, the pH of a neutral solution is 7.83. What is the value of Kw at that temperature?
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2.2×10?16
because at a neutral pH OH=H
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A certain weak acid, HA, has a Ka value of 8.9×10?7.
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0.30
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What determines the pH at the equivalence point of a weak acid and strong base titration?
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conjugate base
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What is the main component of the area before the equivalence point of a weak acid and strong base titration?
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buffer
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How do you estimate pKa for a weak acid and strong base titration?
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look at the mL on the x axis and the neutral pH on the y axis and the point where they meet in the graph is the pKa
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BaSO4 ? Ba2+ + SO42?
Ksp = [Ba2+][SO42?] = 1.1 × 10-11
The value of Ksp indicates
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that there is only a very small
amount of ions in solution
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What is the molar solubility of lead iodide, PbI2, (in [Pb2+])
Ksp = 9.8 × 10-9
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1.4 × 10-3 M
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Calculate the pH of a solution obtained by mixing 50.0 mL hydrochloric acid (with pH = 2.00) and 75.0 mL of hydrobromic acid (with pH = 4.00).
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two strong acids, just add the amounts in moles and add the volumes
[(1.0 × 10-2 mol/L × 0.0500 L) + (1.0 × 10-4 mol/L × 0.0750 L)] / (0.0500 + 0.075)L = 4.06 × 10-3 M pH = 2.39
