1.0×10^(-4) M Cu^+ and 2.0×10^(-3) M Pb^2+

1.0×10^(-4) M Cu^+ and 2.0×10^(-3) M Pb^2+

 

 

A solution contains 1.0×10^(-4) M Cu^+ and 2.0×10^(-3) M Pb^2+.

If a source of I^- is added to this solution gradually,

will PbI2 (Ksp = 1.4×10^(-8)) or CuI (Ksp = 5.3×10^(-12)) precipitate first?

 

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▶ 참고: Ksp [ https://ywpop.tistory.com/2966 ]

▶ 참고: 난용성염의 용해도와 공통이온효과

[ https://ywpop.tistory.com/3141 ]

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PbI2(s) ⇌ Pb^2+(aq) + 2I^-(aq)

Ksp = [Pb^2+] [I^-]^2

 

 

[I^-] = (Ksp / [Pb^2+])^(1/2)

= [(1.4×10^(-8)) / (2.0×10^(-3))]^(1/2)

= 0.00265 M

 

 

 

 

CuI(s) ⇌ Cu^+(aq) + I^-(aq)

Ksp = [Cu^+] [I^-]

 

 

[I^-] = Ksp / [Cu^+]

= (5.3×10^(-12)) / (1.0×10^(-4))

= 5.3×10^(-8) M

---> I^- 이온을 이렇게 쪼매만 넣어도 CuI는 침전된다.

( CuI will precipitate first. )

 

 

 

답: CuI

 

 

 

[ 관련 예제 https://ywpop.tistory.com/15959 ] 0.20 M CrO4^2-, 0.10 M CO3^2-, 0.010 M Cl^-

 

 

 

[키워드] 먼저 침전 기준문서, precipitate first 기준문서