查资料得知在通常状况下:
68%浓硝酸密度是1.405g/ml ;
36%浓盐酸密度是1.18g/ml .
因此400ml水中加3ml浓硝酸后溶液浓度质量分数:
3ml*1.405g/ml*68%/(400ml*1g/ml+3ml*1.405g/ml)
=2.866/(400+4.215)
=0.00709≈0.71%
同理,在400ml水中加4ml浓盐酸溶液浓度质量分数:
4ml*1.18g/ml*36%/(400ml*1g/ml+4ml*1.18g/ml)
=1.699/(400+4.72)
=0.00419≈0.42% .
(两种溶液的体积不一定等于400ml )