已知磷酸的pKa1=2.12,pKa2=7.21,pKa3=12.66,若控制磷酸盐溶液的PH=6.0,则安浓度的大小顺序,,溶液中两种主要的存在型体是
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![已知磷酸的pKa1=2.12,pKa2=7.21,pKa3=12.66,若控制磷酸盐溶液的PH=6.0,则安浓度的大小顺序,,溶液中两种主要的存在型体是](/uploads/image/z/3471263-71-3.jpg?t=%E5%B7%B2%E7%9F%A5%E7%A3%B7%E9%85%B8%E7%9A%84pKa1%3D2.12%2CpKa2%3D7.21%2CpKa3%3D12.66%2C%E8%8B%A5%E6%8E%A7%E5%88%B6%E7%A3%B7%E9%85%B8%E7%9B%90%E6%BA%B6%E6%B6%B2%E7%9A%84PH%3D6.0%2C%E5%88%99%E5%AE%89%E6%B5%93%E5%BA%A6%E7%9A%84%E5%A4%A7%E5%B0%8F%E9%A1%BA%E5%BA%8F%2C%2C%E6%BA%B6%E6%B6%B2%E4%B8%AD%E4%B8%A4%E7%A7%8D%E4%B8%BB%E8%A6%81%E7%9A%84%E5%AD%98%E5%9C%A8%E5%9E%8B%E4%BD%93%E6%98%AF)
已知磷酸的pKa1=2.12,pKa2=7.21,pKa3=12.66,若控制磷酸盐溶液的PH=6.0,则安浓度的大小顺序,,溶液中两种主要的存在型体是
已知磷酸的pKa1=2.12,pKa2=7.21,pKa3=12.66,若控制磷酸盐溶液的PH=6.0,则安浓度的大小顺序,
,溶液中两种主要的存在型体是
已知磷酸的pKa1=2.12,pKa2=7.21,pKa3=12.66,若控制磷酸盐溶液的PH=6.0,则安浓度的大小顺序,,溶液中两种主要的存在型体是
直接用分布系数计算
H3PO4的分布系数=[H+]^3 /{ [H+]^3 +[H+]^2*Ka1 +[H+]*Ka1 *Ka2 +Ka1*Ka2*Ka3}
=(10^-6)^3 / { (10^-6)^3 +(10^-6)^2 *10^-2.12 +(10^-6)*(10^-2.12)* (10^-7.21 )+ (10^-2.12)* (10^-7.21 )*(10^-12.66)
=1.24*10^-4
H2PO4-的分布系数=[H+]^2*Ka1 /{ [H+]^3 +[H+]^2*Ka1 +[H+]*Ka1 *Ka2 +Ka1*Ka2*Ka3}
=(10^-6)^2 *10^-2.12 / { (10^-6)^3 +(10^-6)^2 *10^-2.12 +(10^-6)*(10^-2.12)* (10^-7.21 )+ (10^-2.12)* (10^-7.21 )*(10^-12.66)
=0.941
HPO42-的分布系数=[H+]*Ka1*Ka2 /{ [H+]^3 +[H+]^2*Ka1 +[H+]*Ka1 *Ka2 +Ka1*Ka2*Ka3}
=(10^-6) *(10^-2.12)* (10^-7.21 ) / { (10^-6)^3 +(10^-6)^2 *10^-2.12 +(10^-6)*(10^-2.12)* (10^-7.21 )+ (10^-2.12)* (10^-7.21 )*(10^-12.66)
=0.058
PO43-的分布系数=Ka1*Ka2*Ka3 /{ [H+]^3 +[H+]^2*Ka1 +[H+]*Ka1 *Ka2 +Ka1*Ka2*Ka3}
=(10^-2.12)* (10^-7.21 ) *(10^-12.66) / { (10^-6)^3 +(10^-6)^2 *10^-2.12 +(10^-6)*(10^-2.12)* (10^-7.21 )+ (10^-2.12)* (10^-7.21 )*(10^-12.66)
=1.27*10^-8
因此 H2PO4- >HPO42- >H3PO4 >PO43-