Question

Question #13355

Answer 1

Although there are exceptions, the general trend is that solubility increases from top to bottom of Group 1 and from top to bottom of Group 17.

Explanation:

Here are the solubilities of the Group 1 halides in grams per 100 mL of water at 20 °C.

`bbul(color(white)(mmml)"F"^"-"color(white)(ml)"Cl"^"-"color(white)(ml)"Br"^"-"color(white)(mll)"I"^"-")`
`bb("Li"^"+")"color(white)(m) 0.27color(white)(m) 83.5color(white)(m) 160color(white)(mll) 165`
`bb("Na"^"+")color(white)(ll) 4.28color(white)(m) 35.9color(white)(ml) 90.8color(white)(m) color(red)(178)`
`bb("K"^"+")color(white)(ll) color(red)(94.9)color(white)(mll) 34.4color(white)(ml) 65.2color(white)(m) 144`

The two major exceptions for individual solubilities are marked in `color(red)("red")`.

Note also that the solubility trend for fluorides is the opposite of the trends for chlorides and bromides.