An acidified solution of 0 . 05 M Zn 2 + is saturated with 0 . 1 M H 2 S . What is the minimum molar concentration ( M ) of H + required to prevent the precipitation of ZnS ? Use K sp ( ZnS ) = 1 . 25

Question

An acidified solution of 0 . 05 M Zn 2 + is saturated with 0 . 1 M H 2 S . What is the minimum molar concentration ( M ) of H + required to prevent the precipitation of ZnS ? Use K sp ( ZnS ) = 1 . 25 × 10 - 22 and overall dissociation constant of H 2 S , K NET = K 1 K 2 = 1 × 10 - 21

TestHub · Accepted Answer

For ZnS K sp ( ZnS ) = Zn 2 + × S 2 - = 1 . 25 × 10 - 22 = 0 . 05 × S 2 - = 1 . 25 × 10 - 22 S 2 - = 25 × 10 - 22 For H 2 S H 2 S 0 .1 M ⇌ 2 H + + S 2 − 25 × 10 − 22 K a = H ' S 2 - H 2 S = 1 × 10 - 21 = H + 2 × 25 × 10 - 22 0 . 1 = 1 × 10 - 21 H + 2 = 1 25 H + = 1 5 H + = 0 . 2 M

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