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. acidic, because the cation and the anion hydrolyze to the same extent. 2. neutral, because the cation and the anion hydrolyze to the same extent. 3. neutral, because the cation hydrolyzes to a greater extent than the anion. 4. basic, because the cation hydrolyzes to a greater extent than the anion. 5. acidic, because the anion hydrolyzes to a greater extent than the cation. 6. acidic, because the cation hydrolyzes to a greater extent than the anion. correct 7. basic, because the cation and the anion hydrolyze to the same extent. 8. basic, because the anion hydrolyzes to a greater extent than the cation. 9. neutral, because the anion hydrolyzes to a greater extent than the cation. 10. neutral, because NH 4 OCN is a weak base/weak acid salt. 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 NaCH 3 COO 2. 0.05 M (NH 4 ) 2 SO 4 correct 3. 0.1 M (CH 3 ) 2 NH 2 Cl 4. 0.1 M KNO 2 5. 0.05 M Ca(CN) 2 Explanation: 011 1.0 points Which solution has the highest pH?

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