Hidrat

\begin{equation*}
\begin{array}
& \ce{BaCl2 x H2O & -> & BaCl2 & + & x H2O} \\
100 \% && 85,25 \% && 14,75 \% \\
\end{array}
\end{equation*}

\begin{equation*}
\begin{split}
\ce{massa BaCl2 : H2O & = 85,25 : 14,75} \\\\
\ce{mol BaCl2 : H2O & = \frac {85,25}{137 + 2 \:.\: 35,5} : \frac {14,75}{2 \:.\: 1 + 16}} \\\\
1 : x & = 0,41 : 0,82 \\\\
1 : x & = 1 : 2 \\\\
x & = 2
\end{split}
\end{equation*}

Banyaknya molekul air = 2