ECAT Pakistan · Chemistry

Physical Chemistry and Gas Laws

9 practice questions, each with the answer and an explanation.

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Random questions from this topic, one at a time. You see the answer and the explanation straight after each one.

All 9 questions

  1. In the van der Waals equation of state [P + an^2/V^2] [V - nb] = nR*T, what physical correction does the constant 'a' represent?
  2. What is the root-mean-square speed (v_rms) of oxygen molecules (O2, molar mass = 32 g/mol) at 300 K? (Take R = 8.314 J / mol K)
  3. Under Graham's law of effusion, if an unknown gas effuses 1.414 times faster than sulfur dioxide gas (SO2, molar mass = 64 g/mol), what is the molar mass of the unknown gas?
  4. What is the compressibility factor Z = (PV) / (nR*T) for an ideal gas under all conditions of temperature and pressure?
  5. What is the molarity of a 36.5 percent (by mass) concentrated hydrochloric acid solution having a density of 1.20 g/mL? (Molar mass of HCl = 36.5 g/mol)
  6. Calculate the enthalpy change (delta H) for the cracking reaction C2H6(g) -> C2H4(g) + H2(g) given bond energies: C-C = 348 kJ/mol, C=C = 614 kJ/mol, C-H = 413 kJ/mol, and H-H = 436 kJ/mol.
  7. Which state function remains constant during a Joule-Thomson expansion of a real gas through an insulated porous plug?
  8. What is the oxidation number of chromium in the dichromate polyatomic anion, Cr2O7^(2-)?
  9. Which colligative property measurement is most suitable for determining the high molecular weight of synthetic polymers and proteins?

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