Textbook Problem

One of relatively few reactions that takes place directly between two solids at room temperature is

$\text{Ba}{\left(\text{OH}\right)}_2+8{\text{H}}_{\text{2}}\text{O}\left(s\right)+{\text{ NH}}_{\text{4}}\text{SCN}\left(s\right)\to \text{Ba}{\left(\text{SCN}\right)}_2\left(s\right)+{\text{ H}}_{\text{2}}\text{O}\left(l\right)+{\text{ NH}}_3\left(g\right)$

In this equation, the · 8H₂O in Ba(OH)₂ · 8H₂O indicates the presence of eight water molecules. This compound is called barium hydroxide octahydrate.

a. Balance the equation.

b. What mass of ammonium thiocyanate (NH₄SCN) must be used if it is to react completely with 6.5 g barium hydroxide octahydrate?