Question

Phosphorus trichloride, PCl3, decomposes to form elemental phosphorus and chlorine. The equation is: 4PCl3 → P4 + 6Cl2. Balance the equation and determine the mass in grams of chlorine that would be formed if 25 grams of PCl3 (molecular mass = 137.32 g/mol) decompose. grams of Cl2

Answer 1

Pcl3 mols= 25/137.2mol
cl mols formd by pcl3= 25*1.5/137.2
cl mass= 25*1.5*71/137.2

Answer 2

Answer: 19.4 grams of chlorine

Explanation:

According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.

$4PCl_3\rightarrow P_4+6Cl_2$

According to avogadro's law, 1 mole of every substance weighs equal to the molecular mass and contains avogadro's number $6.023\times 10^{23}$ of particles.

4 moles of $PCl_3$ decompose to give 6 moles of $Cl_2$

$4\times 137=548g$ of  $PCl_3$ decompose to give $6\times 71=426g$ of $Cl_2$

Thus 25 g of $PCl_3$ decompose to give $\frac{426}{548}\times 25=19.4g$ of $Cl_2$

Thus 19.4 grams of chlorine will be produced.