If an electric current is passed through molten sodium chloride, elemental chlorine gas is generated as the sodium chloride is decomposed.

:math> 2NaCl ( 1 ) → 2Na ( s ) + Cl 2 ( g )

at volume of chlorine gas measured at 767 mm Hg at 25 °C would be generated by complete decomposition of 1.25 g of NaCl?

Interpretation:

The volume of chlorine gas generated by complete decomposition of 1.25 g of NaCl is to be calculated.

Concept Introduction:

A mole of a substance is defined as the same number of particles of the substance as present in 12 g of 12 C. The number of particles present in one mole of a substance is 6.023×1023 particles. The number of moles a substance is given as,

n=mM

Where,

• m represents the mass of the substance.
• M represents the molar mass of the substance.

The ideal gas equation is used to represent the relation between the volume, pressure, temperature and number of moles of an ideal gas. The ideal gas equation is given as,

PV=nRT

Where,

• V represents the volume occupied by the ideal gas.
• P represents the pressure of the ideal gas.
• n represents the number of moles of the ideal gas.
• T represents the temperature of the ideal gas.
• R represents the ideal gas constant with value 0.08206 L⋅atm⋅K−1⋅mol−1.

The molar mass of NaCl is 58.44 g⋅mol−1.

The mass of NaCl is 1.25 g.

The temperature of chlorine gas is 25 °C.

The temperature of chlorine gas in Kelvin is given as,

T=25 °C+273.15 K=298.15 K

The pressure of chlorine gas is 767 mm Hg.

The number of mole of substance is given as:

n=mMm

Where,

• m represents the mass of the substance.
• Mm represents the molar mass of the substance.

Substitute the value of the mass and molar mass of NaCl in above equation.

n=1.25 g58.44 g⋅mol−1=0.0214 mol

The number of moles of NaCl reacted is 0.0214 mol.

The given reaction is represented as:

2NaCll→2Nas+Cl2g

Two moles of NaCl produce one mole of Cl2 gas, hence, the relation between the number of moles of NaCl reacted and chlorine gas produced is given as,

n1=n22

Where,

• n1 represents the number of moles of chlorine gas.
• n2 represents the number of moles of NaCl.

Substitute the value of n1 and n2 in the above equation