Question

Sodium chloride is decomposed into the elements sodium and chlorine by means of electrical energy. How much chlorine gas, in grams, is obtained from the decomposition of 146.1-g of NaCl? 2NaCl(s) ⇨ 2Na(s) + Cl2(g)

Answer 1

ANSWER

The mass of Cl2 gas is 88.75 grams

EXPLANATION

Given that;

The mass of NaCl is 146.1 grams

Follow the steps below to find mass of chlorine gas

Step 1; Write the balanced equation of the reaction

$\text{ 2NaCl\lparen s\rparen }\rightarrow\text{ 2Na\lparen s\rparen+ Cl}_{2(g)}$

Step 2; Find the number of moles of chlorine gas using the below formula

$\text{mole = }\frac{\text{ mass}}{\text{ molar mass}}$

Recall, that the molar mass of NaCl is 58.44 g/mol

$\begin{gathered} \text{ mole = }\frac{\text{ 146.1}}{\text{ 58.44}} \\ \text{ mole = 2.5 moles} \end{gathered}$

The number of moles of NaCl is 2.5 moles

Step 3; Find the number of moles of Cl2 using a stoichiometry ratio

Let x represents the number of moles of chlorine

$\begin{gathered} \text{ 2 moles NaCl }\rightarrow\text{ 1 mole Cl}_2 \\ \text{ 2.5 moles NaCl }\rightarrow\text{ x mole Cl}_2 \\ \text{ cross multiply} \\ \text{ 2 moles NaCl }\times\text{ x moles Cl}_2\text{ = 1 mole Cl}_2\text{ }\times\text{ 2.5 moles NaCl} \\ \text{ Isolate x moles Cl}_2 \\ \text{ x moles Cl}_2\text{ = }\frac{2_.5moles\cancel{NaCl}\times1\text{ moles Cl}_2}{2moles\cancel{NaCl}} \\ \text{ x moles Cl}_2\text{ = }\frac{2.5}{2} \\ \text{ x moles Cl}_2\text{ = 1.25 moles} \end{gathered}$

The moles of Cl2 is 1.25 moles

Step 4; Find the mass of Cl2

$\begin{gathered} \text{ mole = }\frac{\text{ mass}}{\text{ molar mass}} \\ \text{ cross multiply} \\ \text{ mass = mole }\times\text{ molar mass} \end{gathered}$

molar mass of Cl2 is 71 g/mol

$\begin{gathered} \text{ mass = 1.25 }\times\text{ 71} \\ \text{ mass = 88.75 grams} \end{gathered}$

The mass of Cl2 gas is 88.75 grams