I'm really new to this, any kind of help would be appreciated.
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asked Jan 31, 2016 at 5:53
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$\begingroup$ I'm voting to close this question as off-topic because OP shows no research efforts. $\endgroup$– user36790Commented Jan 31, 2016 at 8:11
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$\begingroup$ You should some effort from your side, take a look to ideal gas in wikipedia and change your question to more specific about the the details of the procedure. $\endgroup$– rmhleoCommented Jan 31, 2016 at 9:33
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2 Answers
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The density of air can be calculated from the ideal gas law $$\rho_\textrm{air}(p,T)=\frac{p}{R_\textrm{ specific }T}$$ where $p$ is pressure in Pascal and $T$ temperature in Kelvin.
At $300^\circ ~\textrm{C}$ and $100~\textrm{kPa}\,,$ dry air has a density of $\rho_\mathrm{300k,1atm}=1.177~\mathrm{kg\cdot m^{-3}}$ (source)
The average molar mass of air is $M_\textrm{avg} =28.97~\mathrm{g\cdot mol^{-1}}$ (source)
The number density is defined as $$n = \frac{N}{V} = \frac{N_a\cdot \textrm{mols}}{V}$$
This may be the tricky part, but dimensional analysis might be helpful $$\frac{\rho}{M_\textrm{avg}}\equiv\mathrm{\frac{[kg]\cdot[m]^{-3}}{[g]\cdot [mol]^{-1}}\equiv10^{3}[mol]\cdot [m]^{-3}}$$ \begin{align}{n_\mathrm{300,1atm}}& = N_a\cdot \frac{\rho_\mathrm{300,1atm}}{M_\textrm{avg}}\cdot 10^3 \\&= 6.022\times 10^{23}\times\frac{1.177}{28.97}\times 10^3\\ &= 2.45\times 10^{25}~\mathrm{m^{-3}}\;.\end{align}
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1$\begingroup$ Thanks for the formatting edit; it's 4am and I was lazy :) $\endgroup$– cvb0rgCommented Jan 31, 2016 at 8:31
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density = mass / volume so all you need to do is get your volume constant find the volume of air @ 300 k then it is all the same
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$\begingroup$ Welcome to PSE. Please either expand your answer by providing the full procedure or simply make it a comment below the question. This is poor for an answer, it should be a comment. $\endgroup$– rmhleoCommented Jan 31, 2016 at 9:29
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$\begingroup$ The number density is the number of particles in a volume, so your answer is a little short of correct. $\endgroup$ Commented Jan 31, 2016 at 13:43