- #1

archaic

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- Homework Statement
- A mixture of ##\mathrm{NO_{2(g)}}## and ##\mathrm{N_2O_{4(g)}}## at ##63\,\mathrm{C^°}## and ##750\,\mathrm{mmHg}## pressure has a density of ##1.98\,\mathrm{g/L}##. What is the weight% of ##\mathrm{NO_2}## in the mixture?

- Relevant Equations
- ##d=\frac{MP}{RT}##

The total molar mass is ##M=\frac{dRT}{P}=\frac{1.98*0.08206*(63+273.15)}{750/760}=55.3454786\,g/mol##.

We have ##M=aM_1+bM_2## where ##M_1## and ##M_2## are the molar masses of ##\mathrm{NO_2}## and ##\mathrm{N_2O_4}## respectively.

If I consider ##n## moles, I'd have ##m=nM=naM_1+nbM_2=m_1+m_2## and so the weight percentage would be ##\frac{m_1}{m}*100\%=\frac{aM_1}{aM_1+bM_2}*100\%##, but how can I find ##a## and ##b##?

We have ##M=aM_1+bM_2## where ##M_1## and ##M_2## are the molar masses of ##\mathrm{NO_2}## and ##\mathrm{N_2O_4}## respectively.

If I consider ##n## moles, I'd have ##m=nM=naM_1+nbM_2=m_1+m_2## and so the weight percentage would be ##\frac{m_1}{m}*100\%=\frac{aM_1}{aM_1+bM_2}*100\%##, but how can I find ##a## and ##b##?