The solubility product of PbI 2 is 7.2 × 1 0 − 9 . The maximum mass (in grams) of NaI which may be added to 500 mL of 0.005 M Pb ( NO 3 ) 2 solution without any precipitation of PbI 2 (At.wt o

Question

The solubility product of PbI 2 ​ is 7.2 × 1 0 − 9 . The maximum mass (in grams) of NaI which may be added to 500 mL of 0.005 M Pb ( NO 3 ​ ) 2 ​ solution without any precipitation of PbI 2 ​ (At.wt of Na = 23 , I = 127 ).

TestHub · Accepted Answer

To prevent any precipitation of PbI 2 ​ , Q < K s p ​ or, [ Pb 2 + ] [ I − ] 2 < K s p ​ or, ( 0.005 ) [ I − ] 2 < 7.2 × 1 0 − 9 or, [ I − ] < 1.2 × 1 0 − 3 M Hence, the maximum mass of N a I , which can be added = ( 1000 1.2 × 1 0 − 3 ​ × 500 ) × 150 g = 0.09 g

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