Question

A sample of gas occupies 2.5 liters of space. How many moles of gas are there if its pressure is 1.2 atm and temperature is 25 C.

Answer 1

Moles of gas = 0.123

Further explanation

In general, the gas equation can be written  

$\large {\boxed {\bold {PV = nRT}}}$

where  

P = pressure, atm , N/m²

V = volume, liter  

n = number of moles  

R = gas constant = 0.082 l.atm / mol K (P= atm, v= liter),or 8,314 J/mol K (P=Pa or N/m2, v= m³)

T = temperature, Kelvin  

Volume(V) =2.5 L

Pressure(P) = 1.2 atm

Temperature(T) = 25 + 273=298 K

$\tt n=\dfrac{PV}{RT}\\\\n=\dfrac{1.2\times 2.5}{0.082\times 298}\\\\n=0.123~moles$