Question

What is the color of barium sulfate precipitate in the reaction of barium chloride and sodium?

Answer 1

Double Displacement Reaction

• A double displacement reaction is where two elements or compounds simultaneously replace each other.
• In most cases, double displacement reactions result in the formation of a precipitate.
• Example: ${\mathrm{Na}}_2\mathrm{S}+2\mathrm{HCl}\to 2\mathrm{NaCl}+{\mathrm{H}}_2\mathrm{S}$

Reaction of barium chloride and sodium

• A white precipitate of barium sulfate $\left({\mathrm{BaSO}}_4\right)$ is formed when barium chloride $\left({\mathrm{BaCl}}_2\right)$ reacts with sodium sulfate $\left({\mathrm{Na}}_2{\mathrm{SO}}_4\right)$.
• The reaction is as follows:

${\mathrm{BaCl}}_2\left(\mathrm{aq}\right)+{\mathrm{Na}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)\to \underset{\mathrm{white}\mathrm{ppt}.}{{\mathrm{BaSO}}_4\downarrow }+2\mathrm{NaCl}\left(\mathrm{aq}\right)$

• When the reactants are dissolved in water, they become ions, and an ion exchange occurs.
• In aqueous solutions, this is a double displacement reaction in which ions precipitate and ions exchange.