Question

How many air molecules are in a classroom measuring 8.0 m by 6.1 m by 2.6 m , assuming 1 atm pressure and a temperature of 25 ∘C ?

Express your answer using three significant figures.

Answer 1

here,

V = 8 * 6.1 * 2.6 = 126.88 m^3

admiting the atmosphere pressure equal to 1atm and the gas constants equal to 8.2 to this units,

it's that's aplying in the Clapayron equation.

but first let's transform the temperature to kelvin. so:

Tk = Tc + 273

Tk = 25 + 273

Tk = 298 K

so:

pV = nRT

1 * 122.88 = n * 8.2 * 298

solving for n

n = 0.05 mol

1 mol = 6*10^23 molecules

so the number of molecules of air , N = n * 6.022 * 10^23 molecules

N = 3.03 * 10^22 molecules