Question

What is the correct formula for tetraphosphorus tribromide?
A) ${P_2}B{r_5}$
B) ${P_3}B{r_4}$
C) ${P_5}B{r_2}$
D) ${P_4}B{r_3}$

Answer 1

To find the chemical formula of tetraphosphorus tribromide, you need to go accordingly with the name. Tetra is used for the number 4 and tri is used for 3. Tetraphosphorus tribromide contains phosphorus atoms and bromine atoms.

Complete Solution :
Tetraphosphorus tribromide is an inorganic compound containing two different atoms that is, phosphorus and bromine. Let us break the name of tetraphosphorus tribromide. Tetra means four, therefore according to the name, it contains four phosphorus atoms and tri means three, thus it contains three bromine atoms. Chemical symbol for phosphorus is P and the chemical symbol for bromine atoms is Br. Hence, the chemical formula for tetraphosphorus tribromide is ${P_4}B{r_3}$.
- The balanced chemical equation for the formation of tetraphosphorus tribromide (${P_4}B{r_3}$) is:
$2{P_4} + 3B{r_2} \to 2{P_4}B{r_3}$
- Two moles of tetraphosphorus molecules combine with three moles of bromine molecules to form two moles of tetraphosphorus tri bromides.
So, the correct answer is “Option D”.

Additional Information:
Phosphorus is found in many allotropic forms. Important ones are white, red and black. Tetraphosphorus is also known as white phosphorus. White phosphorus consists of one discrete ${P_4}$ molecule. It is less table and therefore quite reactive than other solid forms of phosphorus under normal conditions. Red phosphorus can be obtained by white phosphorus by heating it at 573 K. It is a polymeric chain of ${P_4}$ tetrahedral units.

Note: To write the balanced chemical equation for formation of tetraphosphorus tribromide, you have to count the total number of each element involved in the reaction on the left-hand side i.e, reactant side and the right hand side (product side) and then make them equal.