Question

Using ideal gas equation evaluate R and express its units.

plzz help this.. i need full explanation...very urgent help me.​

Answer 1

ideal gas equation is PV = nRT

where P is pressure of gas

V is volume of gas n is number of mole of gas

R is universal gas constant and T is temperature of gas.

at NTP, normal temperature and pressure, T = 273K, P = 1 atm, n = 1mole (took),

we know, volume of 1mole of gas , V = 22.4Litre

then, R = PV/nT

= (1atm)(22.4Litre)/(1mole)(273K)

= (22.4/273) atm.Litre/mol.K

= 0.082 atm.L/mol.K

hence, value of R = 0.082 atm.L/mol.K

now units of R :

• case 1 : when pressure in atm, volume in litre unit of R = atm.Litre/mol.K
• case 2 : when pressure in N/m², volume in m³ unit of R = N/m².m³/mol.K = Nm/mol.K= J/mol.K [ we know, 1Nm = 1joule ]

also 1 J = 10^7 erg so, unit of R can be written as erg/mol.K