Question

Estimate the number of molecules in an ideal gas at 2atm pressure, 1l volume, and 25^oC temperature.

Answer 1

Answer:

Given, pressure P = 2 atm, volume V = 1 L and temperature T = 25 0C = 25 + 273 K = 298 K

Ideal gas equation PV = nRT, where R is gas constant = 8.314 J/mol.K and n is number of moles

Then, the number of moles n = PV/RT = (2 atm) (1L) / (8.314 J/mol.K) (298 K) = 8.072 x 10-4 mol.atm.L/J

1 atm L = 101.33 J.

Therefore, number of moles n = (8.072 x 10-4) (101.33 J) mol/J = 0.0817 mol.

Avagadro's number NA = 6.022 x 1023 molecule/mol

Therefore, number of molecules N = n NA = (0.817 mol) (6.022 x 1023 molecule/mol) = 4.919 x 1023 molecules.