Question

Which sample contains the smallest number of atoms?

(A) 1.0L of Ar at STP

(B) 1.0L of H2 at STP

(C) 1.0LofAr at 25 C and 760mmHg

(D) 1.0L of H2 at 0C and 900mmHg

Answer 1

The answer is C

Explanation

Ideal gas law equation is

PV = nRT

n= PV/RT

D) n = 1.1842atm × 1L/0.082057 (L atm /mol K) ×273K = 0.0528 mole

No of atom = 6.022×10^23 × 0.0528 ×2 = 6.35×10^22atoms

A) n = 1atm × 1L / 0.082057(L atm / mol K ) × 273K = 0.0446mole

No of atoms = 6.022×10^23 × 0.0446 mole ×1= 2.68×10^22 atoms

B) 6.022 × 10^23×0.0446 × 2 = 5.37 × 10^22atoms

C) n = 1L × 1atm / 0.082057(L atm / mol K ) × 298K

= 0.0409 mole

no of atoms = 0.0409× 6.022×10^23 × 1= 2.46× 10^22atoms