取1.43g Na2CO3?10H2O溶于水配成100mL溶液,Na+ 物质的量浓度为______;取出20mL该溶液用蒸馏水稀释,使N

2025-05-10 18:31:52
推荐回答(1个)
回答1:

根据n=

m
M
求的Na2CO3?10H2O的物质的量n=
1.43g
286g/mol
=0.005mol,则n(Na+)=0.01mol,故Na+ 物质的量浓度为C=
n
V
=
0.01mol
0.1L
=0.1mol/L;
设加入蒸馏水的体积为XL,根据C(Na+)=0.1mol/L可知C(Na2CO3)=0.05mol/L,根据CV=CV可知:0.05mol/L×0.02L=0.004mol/L×(0.02L+XL),解得:X=0.23L,即230ml.
故答案为:0.1mol/L;230ml.