VmLAl2(SO4)3溶液中含Al3+ a g,取V/4mL溶液稀释到4VmL,则稀释后溶液中硫酸根离子的物质的量浓度为?A (125/9)× a/V mol/L b (125/18)× a/V mol/L c (125/36)× a/V mol/L d (125/54)× a/V mol/L
问题描述:
VmLAl2(SO4)3溶液中含Al3+ a g,取V/4mL溶液稀释到4VmL,则稀释后溶液中硫酸根离子的物质的量浓度为?
A (125/9)× a/V mol/L
b (125/18)× a/V mol/L
c (125/36)× a/V mol/L
d (125/54)× a/V mol/L
答
n(AL3+)=a/27mol
n(SO42-)=a/27/2*3=a/18mol
n`=a/18*(1/4)=a/72mol
c=n/v=a/72mol/(4*0.001)L=(125/36)*a/v mol
选C