Chemistry, 29.07.2019 01:30, maddielr17

How much energy is required to decompose 800 g of pcl3, according to the reaction below? the molar mass of pcl3 is 137.32 g/mol and may be useful. 4 pcl3(g) → p4(s) + 6 cl2(g) δh∘rxn = +1207 kj how much energy is required to decompose 800 of , according to the reaction below? the molar mass of is 137.32 and may be useful. 4 (g) (s) + 6 (g) = +1207 1.76×103 kj 4.53×103 kj 2.31×103 kj 6.72×103 kj 5.90×103 kj?

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The amount of energy required to decompose 800 g of ${\text{PC}}{{\text{l}}_{\text{3}}}$ is $\boxed{{\text{1757}}{\text{.8 kJ}}}$ .

Further explanation:

Decomposition reactions:

The opposite of combination reactions is called a decomposition reaction. Here, a single reactant gets broken into two or more products. Such reactions are usually endothermic because energy is required to break the existing bonds between the reactant molecules.

Examples of decomposition reactions are as follows:

(a) $2{{\text{H}}_2}{{\text{O}}_2}\to2{{\text{H}}_2}{\text{O}}+{{\text{O}}_2}$

(b) $2{\text{NaCl}}\to{\text{2Na + C}}{{\text{l}}_2}$

Stoichiometry of a reaction is used to determine the amount of species present in the reaction by the relationship between reactants and products. It is used to determine moles of a chemical species when moles of other chemical species present in the reaction is given.

Consider the general reaction,

${\text{A}}+2{\text{B}}\to3{\text{C}}$

Here,

A and B are reactants.

C is the product.

One mole of A reacts with two moles of B to produce three moles of C. The stoichiometric ratio between A and B is 1:2, the stoichiometric ratio between A and C is 1:3 and the stoichiometric ratio between B and C is 2:3.

The decomposition of ${\text{PC}{\text{l}_3}$ occurs as follows:

${\text{4PC}}{{\text{l}}_3} \to {{\text{P}}_4} + 6{\text{C}}{{\text{l}}_2}$

The formula to calculate the moles of ${\text{PC}}{{\text{l}}_3}$ is as follows:

${\text{Moles of PC}}{{\text{l}}_3}=\frac{{{\text{Given mass of PC}}{{\text{l}}_3}}}{{{\text{Molar mass of PC}}{{\text{l}}_3}}}$ …… (1)

The given mass of ${\text{PC}}{{\text{l}}_3}$ is 800 g.

The molar mass of ${\text{PC}}{{\text{l}}_3}$ is 137.33 g/mol.

Substitute these values in equation (1).

$\begin{aligned}{\text{Moles of PC}}{{\text{l}}_3}&=\left( {{\text{800 g}}}\right)\left({\frac{{{\text{1 mol}}}}{{{\text{137}}{\text{.33 g}}}}}\right)\\&=5.8253\;{\text{mol}}\\\end{aligned}$

From the balanced chemical reaction of decomposition of ${\text{PC}}{{\text{l}}_3}$ , 4 moles of ${\text{PC}}{{\text{l}}_3}$ require 1207 kJ of energy. So the amount of energy required to decompose 5.8253 moles of ${\text{PC}}{{\text{l}}_3}$ is calculated as follows:

$\begin{aligned}{\text{Amount of energy required}}&=\left({5.8253\;{\text{mol PC}}{{\text{l}}_3}}\right)\left({\frac{{{\text{1207 kJ}}}}{{{\text{4 mol PC}}{{\text{l}}_3}}}}\right)\\&={\text{1757}}{\text{.7842}}\;{\text{kJ}}\\&\approx{\text{1757}}{\text{.8 kJ}}\\\end{aligned}$

So the amount of energy required to decompose 800 g of ${\mathbf{PC}}{{\mathbf{l}}_{\mathbf{3}}}$ is 1757.8 kJ.

Learn more:

1. Balanced chemical equation: link

2. Determine how many moles of water produce: link

Answer details:

Grade: Senior School

Subject: Chemistry

Chapter: Mole Concept

Keywords: PCl3, P4, Cl2, 6 Cl2, 4 PCl3, amount of energy, 1757.8 kJ, moles of PCl3, molar mass, given mass, 800 g, 137.33 g/mol, stoichiometry, reactant, product, decomposition reaction, 1207 kJ.

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