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ENGR5002 / Week 1 / L1 Introduction
E6.1Exercise sheetCurrent specThird8 min

Week 1 Exercises, Exercise 6 part 1

Air at sea level has p0=101 325 Pap_0 = 101\,325\ \mathrm{Pa} and uniform temperature T=300 KT = 300\ \mathrm{K}; R=8.314 J mol−1 K−1R = 8.314\ \mathrm{J\,mol^{-1}\,K^{-1}}. Its molar composition is 78% N2\mathrm{N_2} (M=28.02 g mol−1M = 28.02\ \mathrm{g\,mol^{-1}}), 21% O2\mathrm{O_2} (32.00 g mol−132.00\ \mathrm{g\,mol^{-1}}) and 1% Ar (39.95 g mol−139.95\ \mathrm{g\,mol^{-1}}).

  1. (a)
    Calculate the average molar mass of the mixture.
  2. (b)
    [Added, needed for Exercise 6 parts 2-4] Using ρ=pMw/(RT)\rho = p M_w / (R T), calculate the density of air at sea level.