Question

Write a balanced chemical equation for the following and identify the type of reaction of each case:

$\mathrm{KBr}+{\mathrm{BaI}}_2\to \mathrm{KI}+{\mathrm{BaBr}}_2$

Answer 1

Balanced equation:

• A balanced equation is an equation in which the number of atoms for every element on the reactant and product side should be equal.
• A chemical equation should be balanced by putting numbers.
• The given equation is as follows:

$\mathrm{KBr}\left(\mathrm{aq}\right)+{\mathrm{BaI}}_2\left(\mathrm{aq}\right)\to \mathrm{KI}\left(\mathrm{aq}\right)+{\mathrm{BaBr}}_2\left(\mathrm{s}\right)$

• The number of atoms on the reactant and product side

Atoms	Reactant	Product
$\mathrm{K}$	$1$	$1$
$\mathrm{Br}$	$1$	$2$
$\mathrm{Ba}$	$1$	$1$
$\mathrm{I}$	$2$	$1$

• The bromide on the reactant and product side is not balanced, on balancing it we get

$2\mathrm{KBr}\left(\mathrm{aq}\right)+{\mathrm{BaI}}_2\left(\mathrm{aq}\right)\to 2\mathrm{KI}\left(\mathrm{aq}\right)+{\mathrm{BaBr}}_2\left(\mathrm{s}\right)$

Atoms	Reactant	Product
$\mathrm{K}$	$2$	$2$
$\mathrm{Br}$	$2$	$2$
$\mathrm{Ba}$	$1$	$1$
$\mathrm{I}$	$2$	$2$

• So, the balanced equation is $2\mathrm{KBr}\left(\mathrm{aq}\right)+{\mathrm{BaI}}_2\left(\mathrm{aq}\right)\to 2\mathrm{KI}\left(\mathrm{aq}\right)+{\mathrm{BaBr}}_2\left(\mathrm{s}\right)$
• The reaction that takes place here is a Double Displacement Reaction because the bromide and iodide ions are shifted.

Double Displacement Reaction

• Two atoms or a group of atoms shift positions to generate new compounds in a double displacement process.
• The double displacement reaction is represented in general as,

$\mathrm{AB}+\mathrm{CD}\to \mathrm{AC}+\mathrm{BD}$