A 1.00-L mixture of helium, neon, and argon has a total pressure of 662 mmHg at 298 K. If the partial pressure of helium is 341 mmHg and the partial pressure of neon is 112 mmHg, what mass of argon is present in the mixture?

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SORT The problem gives you the partial pressures of two of the three components in a gas mixture, along with the total pressure, the volume, and the temperature, and asks you to find the mass of the third component. STRATEGIZE You can find the mass of argon from the number of moles of argon, which you can calculate from the partial pressure of argon and the ideal gas law. Begin by using Dalton's law to determine the partial pressure of argon. Then use the partial pressure of argon together with the vol- ume of the sample and the temperature to find the number of moles of argon. Finally, use the molar mass of argon to calculate the mass of argon from the number of moles of argon. GIVEN: PHE = 341 mmHg, Re = 112 mmHg, Ptotal = 662 mmHg, V = 1.00 L, T = 298 K FIND: MAT CONCEPTUAL PLAN Plot PHe, PNe PAT, V, T nAr PAR Ptot - PHe + PNE + PAT PV = nRT 39.95 g Ar 1 mol Ar nAr mar RELATIONSHIPS USED Ptotal = He + Ne + Par (Dalton's law) PV = nRT (ideal gas law) molar mass Ar = 39.95 g/mol