在50ml0.1mol/lAgNO3溶液中加入密度为0.93g/cm3,质量分数为0.182的氨水30ml后,加水稀释到100ml,计算：

题目

在50ml0.1mol/lAgNO3溶液中加入密度为0.93g/cm3,质量分数为0.182的氨水30ml后,加水稀释到100ml,计算：
溶液中Ag+,[Ag(NH3)2]+和NH3的浓度?

答案

0.93g/cm3,质量分数为0.182的氨水30ml:
n(NH3)=30*0.93*0.182 /17=0.30mol
50ml0.1mol/lAgNO3:
n(Ag+)=0.005mol
则总银浓度:c(Ag)=0.005/0.1=0.05mol/L
游离的氨浓度c(NH3)=(0.30-0.005*2)/0.1=2.9mol/L
查表:累积稳定常数:β1=10^3.40 β2=10^7.40 数据来自北师大版《无机化学》
[Ag+]= c(Ag)* 1/ { 1 + β1*[NH3] + β2* [NH3]^2 }
=0.050 * 1 /{ 1 + 10^3.40 *2.9 + 10^7.40 *2.9^2}
=2.4*10^-10(mol/L)
[Ag(NH3)+]= c(Ag)* { β1*[NH3] }/ { 1 + β1*[NH3] + β2* [NH3]^2 }
=0.050 * 10^3.40 *2.9 /{ 1 + 10^3.40 *2.9 + 10^7.40 *2.9^2}
=1.7*10^-6(mol/L)
[Ag(NH3)2+]= c(Ag)* { β2* [NH3]^2 }/ { 1 + β1*[NH3] + β2* [NH3]^2 }
=0.050 * 10^7.40 *2.9^2 /{ 1 + 10^3.40 *2.9 + 10^7.40 *2.9^2}
=0.050(mol/L)