å°150ml 0.01mol/L H2Sçç©è´¨çé=1.5mmol
50ml 0.30mol/L Na2Sçç©è´¨çé=15mmol
H2S +Na2S =2NaHS
1 1 2
1.5 1.5 3
å æ¤å¾å°ç溶液æ¯NaHS 3mmol Na2S 13.5mmol
æ¾ç¶å½¢æçæ¯ç¼å²æº¶æ¶²
HS- <==>H+ +S2-
Ka2=[H+]*[S2-]/[HS-]=[H+]*n[S2-]/n[HS-]=[H+] *3mmol/ 13.5mmol
[H+]=4.5*Ka2=4.5*1.3x10^-13=5.85*10^-13
pH=12.23
====
æ¯å¦æH2Sæµåº¦åé误
å¦ææ¯150ml 0.1mol/L H2S
150ml 0.1mol/L H2Sçç©è´¨çé=15mmol
50ml 0.30mol/L Na2Sçç©è´¨çé=15mmol
H2S +Na2S =2NaHS
1 1 2
15 15 30
å æ¤å¾å°ç溶液æ¯NaHS 30mmol
NaHSå¨è´¨å论æ¯ä¸¤æ§ç©è´¨
[H+]=约=(Ka1*Ka2)^1/2=(1.1x10^-7*1.3x10^-13)^1/2=1.2*10^-10
pH=9.92
æPH=(pKa1+pKa2)/2=9.92æ¥èªï¼æ±å©å¾å°çåç
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