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One mole of a monoatomic gas is mixed with three moles of a diatomic gas. The molecular specific heat of mixture at constant volume is \frac{\alpha^{2}}{4} \mathrm{R} \mathrm{J} / \mathrm{mol} \: \: \mathrm{K}; then the value of \alpha will be__________ (Assume that the given diatomic gas has no vibrational mode).

Option: 1

3


Option: 2

-


Option: 3

-


Option: 4

-


Answers (1)

best_answer

For monoatomic gas ,

\mathrm{V_{1}=\frac{5}{3},n_{1}=1}

For diatomic gas,

\mathrm{V_{2}=\frac{7}{5},n_{2}=3}

\mathrm{U=U_{1}+U_{2}}

\mathrm{n_{\text {mix }}\left(c_v\right)_{\operatorname{mix}} T =n_1\left(c_v\right)_1 T+n_2\left(c_v\right)_2 T }

\mathrm{\frac{(\left.n_1+n_2\right) R}{v_{\operatorname{mix}}-1} =\frac{n_1 R}{v_1-1}+\frac{n_2 R}{v_2-1} }

\mathrm{\frac{4}{V_{\operatorname{mix}}-1} =\frac{1}{2 / 3}+\frac{3}{2 / 5} }

                   \mathrm{=\frac{3}{2}+\frac{15}{2} }

\mathrm{\frac{4}{v_{\text {mix }}-1} =9}

\mathrm{\frac{4}{9}+1 =V_{\text {mix }} }

\mathrm{v_{\text {mix }} =\frac{13}{9}}

\mathrm{\left ( C_{v} \right )_{mix}=\frac{R}{v_{mix}-1}=\frac{\alpha ^{2}}{4}R}

\mathrm{\frac{1}{\left ( \frac{13}{9}-1 \right )}=\frac{\alpha ^{2}}{4}}

\mathrm{\frac{9}{4}=\frac{\alpha ^{2}}{4}}

\mathrm{\alpha =3}

The value of \mathrm{\alpha} is 3








 

Posted by

rishi.raj

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