常温ä¸
氢氧åéå¼å§æ²æ·æ¶PH约为9.8ï¼æ°¢æ°§åé为ç½è²æ²æ·ã
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1ã氢氧åéç
溶度积为ï¼Ksp[Mg(OH)2]= 1.8Ã10^ï¼-11ï¼
氢氧åéç溶度积ç
表达å¼ä¸ºï¼Ksp[Mg(OH)2]= c(Mg2+)à [ c(OH-)] ^2
æ ¹æ®æ°¢æ°§åé饱å溶液ä¸ç离åæµåº¦å
³ç³»ï¼ c(OH-)= c(Mg2+)à 2 代å
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Ksp[Mg(OH)2]= c(Mg2+)Ã [ c(OH-)] ^2
= 1/2 Ã c(OH-)Ã [ c(OH-)] ^2
= 1/2 Ã [ c(OH-)] ^3
å¾Ksp[Mg(OH)2]= 1/2 Ã [ c(OH-)] ^3
2ã解å¾æ°¢æ°§åé饱å溶液ä¸c(OH-)ä¸ºï¼ 7.11379 Ã10^ï¼-3ï¼mol/L
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[ c(OH-)] = ï¼2 Ã Ksp ï¼^ï¼1/3ï¼
= [ 2 Ã 1.8Ã10^ï¼-11ï¼]^ï¼1/3ï¼
= 7.11379 Ã10^ï¼-3ï¼mol/L
3ã室温æ¶æ ¹æ®
æ°´ç离å积计ç®åºæº¶æ¶²ä¸c(H+)为ï¼= 1.4057211Ã10^ï¼-10ï¼ mol/L
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c(OH-)Ã c(H+)=Kw= 10^ï¼-14ï¼
å c(H+)= 10^ï¼-14ï¼/c(OH-)= 10^ï¼-14ï¼/ 7.11379 Ã10^ï¼-3ï¼
= 1.4057211Ã10^ï¼-10ï¼ mol/L
4ãæ ¹æ® c(H+)计ç®æº¶æ¶²çPH为ï¼9.8521
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pH = - lg [ c(H+) ] = - lg [ 1.4057211Ã10^ï¼-10ï¼ ] = 9.8521