Question

Write the balanced equation when phosphorous burns in oxygen to form phosphorous pentoxide.

Answer 1

Balanced chemical equation:

• “A balanced equation for a chemical reaction is where the number of atoms and charge of each chemical element is equal in both reactants and products.”

The reaction between phosphorus and oxygen:

• When phosphorus is made to burn in oxygen, it results in the formation of phosphorus pentoxide.
• $$\begin{gathered} {\mathrm{P}}_4\left(\mathrm{s}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\stackrel{∆}{\to }{\mathrm{P}}_2{\mathrm{O}}_5\left(\mathrm{s}\right) \\ \left(\mathrm{Phosphorous}\right)\left(\mathrm{oxygen}\right)(\mathrm{Phosphorous}\mathrm{pentoxide}) \end{gathered}$$

Element	Reactant side	Product side
$\mathrm{P}$	$4$	$2$
$\mathrm{O}$	$2$	$5$

• Both phosphorus and oxygen are not balanced, by balancing the oxygen on the reactant and product side, the whole equation gets balanced.
• $$\begin{gathered} {\mathrm{P}}_4\left(\mathrm{s}\right)+5{\mathrm{O}}_2\left(\mathrm{g}\right)\stackrel{\mathrm{heat}}{\to }2{\mathrm{P}}_2{\mathrm{O}}_5\left(\mathrm{s}\right) \\ \left(\mathrm{Phosphorous}\right)\left(\mathrm{Oxygen}\right)(\mathrm{Phosphorous}\mathrm{pentoxide}) \end{gathered}$$

Element	Reactant side	Product side
$\mathrm{P}$	$4$	$4$
$\mathrm{O}$	$10$	$10$

• Thus the balanced equation is as follows:
• $$\begin{gathered} {\mathrm{P}}_4\left(\mathrm{s}\right)+5{\mathrm{O}}_2\left(\mathrm{g}\right)\stackrel{\mathrm{heat}}{\to }2{\mathrm{P}}_2{\mathrm{O}}_5\left(\mathrm{s}\right) \\ \left(\mathrm{Phosphorous}\right)\left(\mathrm{Oxygen}\right)(\mathrm{Phosphorous}\mathrm{pentoxide}) \end{gathered}$$