Question

How would you estimate the number of gas molecules in one cubic meter of air in the classroom on an average day?

Answer 1

We would use the molar volume of an ideal gas at `"SLC"` as an approximation. There are are approx 41 moles of air, thus `41*molxxN_A` `=` `"number of gas molecules"`

Explanation:

Given the molar volume, we know that 1 mole of an ideal gas occupies `24.5*L` at `"SLC"`, i.e. the molar volume is `24.5*L*mol^-1`.

Knowing that `1` `m^3` `=` `1000*L` we simply divide this quantity by the first:

`"Number of moles"` `=` `(1000*L)/(24.5*L*mol^-1)` `=` `41*"moles"`

Each mole of gas contains `N_A` gas molecules, whose behaviour is assumed to be ideal.

Thus, `"number of gas molecules"` `41*molxxN_A` `=` `41*molxx6.022xx10^23*mol^-1` .