化学问题

seelingUID: 171316

practice book
7 Solutions of the following compounds, all at the same molality, were prepared. which solution has the lowest freezing point?
A KBr B Al(NO3) C CH3COONa D NaNO2 E MgCl2
8 which of the following gases has the largest value of b in the van der Waals equation shown above?
A CH4 B CCl4 C HCl D H2O E N2
16 given that a certain organic compound absorbs light in the visible region, it CANNOT be true that it
A is aromatic
B is an alkane
C is colored
D contains a nitro group
E contains a chloride atom

哪位指点指点

xenonUID: 2149750

1 应该是稀溶液的性质
　我的书上讲的是非电解质溶液的性质，但这里的都是电解质溶液，可以写出电离方程
　式，然后看离子数的摩尔总数。我不确定，不过我是这么理解的。好像还作过一个相
　同摩尔量的氯化钠溶液和蔗糖溶液渗透压的题目，前者是后者的２倍

2 b是跟分子自身体积有关的常数，CCl4是四面体结构，Cl又比H大，所以应该是最大的吧

３吸收紫外可见光应该是n,pi电子跃迁产生的，只有烷烃没有非键电子和pi电子