equilibrium which means that H radicalbig K a C BH radicalBig 6 66667 10 6 0 4

Equilibrium which means that h radicalbig k a c bh

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equilibrium which means that [H + ] = radicalbig K a · C BH + = radicalBig (6 . 66667 × 10 - 6 ) (0 . 4) = 0 . 00163299 M pH = - log(0 . 00163299) = 2 . 78702 009 1.0 points Consider the ionization constants cyanic acid (HOCN) : K a = 3 . 5 × 10 - 4 ; ammonia (NH 3 ) : K b = 1 . 8 × 10 - 5 . A solution of ammonium cyanate (NH 4 OCN) is 1. basic, because the cation hydrolyzes to a greater extent than the anion. 2. acidic, because the cation and the anion hydrolyze to the same extent. 3. acidic, because the cation hydrolyzes to a greater extent than the anion. correct 4. basic, because the cation and the anion hydrolyze to the same extent. 5. basic, because the anion hydrolyzes to a greater extent than the cation. 6. neutral, because the cation hydrolyzes to a greater extent than the anion. 7. acidic, because the anion hydrolyzes to a greater extent than the cation. 8. neutral, because the anion hydrolyzes to a greater extent than the cation. 9. neutral, because NH 4 OCN is a weak base/weak acid salt. 10. neutral, because the cation and the anion hydrolyze to the same extent. Explanation: Compare NH + 4 + H 2 O NH 3 + H 3 O + K a = 1 K b = 1 1 . 8 × 10 - 5 = 55555 . 6 OCN - + H 2 O HOCN + OH - K b = 1 K a = 1 3 . 5 × 10 - 4 = 2857 . 14 The producton of H 3 O + occurs to the greater extent, making the solution acidic. 010 1.0 points Consider the ionization constants CH 3 COOH : K a = 1 . 8 × 10 - 5 HNO 2 : K a = 4 . 5 × 10 - 4 HCN : K a = 4 . 3 × 10 - 10 NH 3 : K b = 1 . 8 × 10 - 5 (CH 3 ) 2 NH : K b = 7 . 4 × 10 - 4 Predict which of the following solutions would have the lowest pH. 1. 0.1 M (CH 3 ) 2 NH 2 Cl 2. 0.1 M NaCH 3 COO 3. 0.05 M (NH 4 ) 2 SO 4 correct 4. 0.05 M Ca(CN) 2 5. 0.1 M KNO 2 Explanation: 011 1.0 points Which solution has the highest pH?
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  • Fall '07
  • Holcombe
  • pH, kA

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