A container contains 4 ~g H ₂, 4 ~g He and certain amount of ' Ne ' at a certain temperature. What is the mass of 'Ne' required so that the partial pressure exerted by ' Ne ' is equal to the partial pressure of He ?

Step-by-step solution

Dalton's Law implies that partial pressures are equal when mole fractions are equal, which requires equal numbers of moles for gases in the same container at constant temperature. Given 4 g of H₂ ( M = 2 g/mol ) and 4 g of He ( M = 4 g/mol ), the moles are n_ H₂ = 4/2 = 2 mol and n_ He = 4/4 = 1 mol . For P_ Ne = P_ He , the mole fractions must match, so n_ Ne = n_ He = 1 mol . With M_ Ne = 20 g/mol , the required mass is 1 20 = 20 g . Final answer: 20 g