Gas Mixtures: Mole Fractions, Dalton's Law, and Amagat's Law

Question-and-answer flashcards covering mole and mass fractions, Dalton's law, Amagat's law, and applications of gas mixtures in engineering.

What is the mole fraction of component i in a gas mixture?

Yi = ni / n_total (moles of i divided by total moles).

How is the mass fraction defined and how is it related to mole fraction?

Mass fraction of component i is mi / m_total; related to mole fractions through molecular weights.

What are the approximate mole fractions for N2, O2, and Ar in dry air?

N2 ≈ 0.78, O2 ≈ 0.21, Ar ≈ 0.01.

State Dalton's law for ideal gas mixtures.

Ptotal = sum Pi; Pi = Yi × Ptotal.

If total pressure is 200 kPa and YO2 = 0.21, what is PO2?

P_O2 = 0.21 × 200 kPa = 42 kPa.

State Amagat's law for volumes.

V_total = sum Vi; Vi is the volume gas i would occupy alone at the same T and P.

Do Dalton's and Amagat's laws apply to ideal gases and do they agree?

Yes; for ideal gases both laws give consistent results.

What average properties are used to analyze gas mixtures?

Molar mass, gas constant, internal energy, enthalpy, and specific heats.

How is moist air related to dry air?

Moist air = dry air + water vapor.

What is the key takeaway for analyzing gas mixtures?

Use mole or mass fractions and apply Dalton's and Amagat's laws; gas mixtures can be analyzed with the same tools as pure gases.