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Explain why pure liquids and solids can be ignored while writing the equilibrium constant expression?
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[Pure liquid] or [Pure solid]
\(\begin{aligned}
&=\frac{\text { No. of moles }}{\text { Volumein } L}=\frac{\text { Mass } / \text { Mol.mass }}{\text { Volume }} \\
&=\frac{\text { Mass }}{\text { Volume }} \times \frac{1}{\text { Mol. mass }}=\frac{\text { Density }}{\text { Mol.mass }}
\end{aligned}\)
As density of a pure liquid or pure solid is constant at constant temperature and molecular mass is also constant, therefore, their molar concentrations are constant and thus not included into the equilibrium constant.
\(\begin{aligned}
&=\frac{\text { No. of moles }}{\text { Volumein } L}=\frac{\text { Mass } / \text { Mol.mass }}{\text { Volume }} \\
&=\frac{\text { Mass }}{\text { Volume }} \times \frac{1}{\text { Mol. mass }}=\frac{\text { Density }}{\text { Mol.mass }}
\end{aligned}\)
As density of a pure liquid or pure solid is constant at constant temperature and molecular mass is also constant, therefore, their molar concentrations are constant and thus not included into the equilibrium constant.
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