Question

How many molecules of oxygen occupy a 1.0 L flask at 65°C and 778 torr?

Answer 1

we have:

P = 778.0 torr

= (778.0/760) atm

= 1.0237 atm

V = 1.0 L

T = 65.0 oC

= (65.0+273) K

= 338 K

find number of moles using:

P * V = n*R*T

1.0237 atm * 1 L = n * 0.08206 atm.L/mol.K * 338 K

n = 3.689*10^-2 mol

we have below equation to be used:

number of molecules = number of mol * Avogadro’s number

= 3.689*10^-2 * 6.022*10^23 molecules

= 2.22*10^22 molecules

Answer: 2.22*10^22 molecules