# Question 13355

Aug 26, 2017

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.

$\boldsymbol{\underline{\textcolor{w h i t e}{m m m l} \text{F"^"-"color(white)(ml)"Cl"^"-"color(white)(ml)"Br"^"-"color(white)(mll)"I"^"-}}}$
bb("Li"^"+")"color(white)(m) 0.27color(white)(m) 83.5color(white)(m) 160color(white)(mll) 165#
$\boldsymbol{\text{Na"^"+}} \textcolor{w h i t e}{l l} 4.28 \textcolor{w h i t e}{m} 35.9 \textcolor{w h i t e}{m l} 90.8 \textcolor{w h i t e}{m} \textcolor{red}{178}$
$\boldsymbol{\text{K"^"+}} \textcolor{w h i t e}{l l} \textcolor{red}{94.9} \textcolor{w h i t e}{m l l} 34.4 \textcolor{w h i t e}{m l} 65.2 \textcolor{w h i t e}{m} 144$

The two major exceptions for individual solubilities are marked in $\textcolor{red}{\text{red}}$.

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