At 60°C, dinitrogen tetroxide is fifty percent dissociated. Calculate the standard free energy change at this temperature and at one atmosphere.

Solution

N₂O₄ (g) $rightwards harpoon over leftwards harpoon$ 2NO₂(g)
Initial 1 mole 0
At eqn. 1 - 0.5 2 x 0.5
= 0.5 mol = 1 mol
Total number of moles = 0.5 + 1 = 1.5 mol
$straight p subscript straight N subscript 2 straight O subscript 4 end subscript space equals fraction numerator 0.5 over denominator 1.5 space end fraction cross times 1 space space atm space equals space 1 third atm straight p subscript NO subscript 2 end subscript space equals space fraction numerator 1 over denominator 1.5 end fraction cross times 1 space atm space equals space 2 over 3 atm$

According to law of chemical equilibrium
$straight K subscript straight p space equals space straight p subscript NO subscript 2 end subscript over straight p subscript straight N subscript 2 straight O subscript 4 end subscript space equals space fraction numerator open parentheses begin display style 2 over 3 end style close parentheses squared over denominator open parentheses begin display style 1 third end style close parentheses end fraction space equals space 1.33 space atm$

We know,

$increment straight G to the power of 0 space equals space minus 2.303 space RT space log space straight K subscript straight p space space space space space space... left parenthesis 1 right parenthesis$
Substituting the values in equation (1), we get
$increment straight G to the power of 0 space equals space minus 2.303 space left parenthesis 8.314 space JK to the power of negative 1 end exponent space mol to the power of negative 1 end exponent right parenthesis thin space left parenthesis 333 space straight K right parenthesis space log space 1.33 space space space space space space space space equals space minus 790 space straight J space mol to the power of negative 1 end exponent$

Some More Questions From Thermodynamics Chapter

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Thermodynamics

At 60°C, dinitrogen tetroxide is fifty percent dissociated. Calculate the standard free energy change at this temperature and at one atmosphere.

Some More Questions From Thermodynamics Chapter

Define an isolated system.

Define intensive properties.

Define extensive properties.

Why all living systems need to be 'open systems'?

Define state variables of a system.

From thermodynamic point of view, to which system the animals and plants belong?

What is a state function?

A thermodynamic state function is a quantity

What is reversible process in thermodynamics?

Define irreversible change.

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