Exam 1 - Gases

Wed 9/14 7-9pm

Results




Average 49970: 78.76

Avegage 49975: 80.68

ALL Average: 79.67

Median: 79.67

Std Dev: 17.00

Total 100's: 58

What the Student Brings to Exams
  • official UT ID card (with your picture and name on it)
  • a simple scientific calculator (not a graphing calculator)
  • a pencil(s) and eraser
  • memorized formulas in your head - not on paper or anything else
  • nothing else is allowed
What we provide for the Exams
  • A printed copy of the exam (every exam has a unique version number on it).
  • An answer sheet for the exam. This is a bubblesheet for your answers.
  • An exam cover page that has ALL needed conversion factors and data. No formulas will be given.
  • A periodic table of the elements with symbols, atomic number, and atomic weights.
What Formulas the Student Should Memorize

The Ideal Gas Law (IGL):

\[PV=nRT\]

Gas Laws "contained" in the IGL:

Boyle's Law:    \(P_1V_1 = P_2V_2\)    (constant n, T)


Charles' Law:    \(\displaystyle{V_1\over T_1} = {V_2\over T_2}\)    (constant n, P)


Avogadro's Law:    \(\displaystyle{V_1\over n_1} = {V_2\over n_2}\)    (constant P, T)


Gay-Lussac's Law:    \(\displaystyle{P_1\over T_1} = {P_2\over T_2}\)    (constant n, V)


Air Up Your Tires Law:    \(\displaystyle{P_1\over n_1} = {P_2\over n_2}\)    (constant V, T)


Difficult to Do This Law:    \(n_1T_1 = n_2T_2\)    (constant P, V)


You will not be tested on the naming of these laws.

and because density (ρ) is m/V and molar mass (M) is m/n, then you also know the molar mass of an ideal gas via:

\[{M={\rho RT\over P}}\]

Dalton's Law of Partial Pressures
\[P_{\rm total}=P_{\rm A} + P_{\rm B} + P_{\rm C} + \cdots\]

mole fraction of gas A:   \(x_{\rm A}=P_{\rm A}/P_{\rm total}\)

Van der Waal's Equation of State (Gas Model)
\[\left(P+a{n^2 \over V^2}\right)(V-nb)=nRT\]

Root mean squared velocity of a gas
\[{v_{\rm rms}=\sqrt{3RT \over M}}\]

Comparing rms velocities of two different gases at the same temperature
\[{{v_1\over v_2}=\sqrt{M_2 \over M_1}}\]

The average kinetic energy of an ideal gas
\[E_{\rm k} = U = {3\over 2}RT = {1\over 2}mv^2\]

FYI: There will be no nomenclature (aka naming) on this exam. Nomenclature will be a portion of exam 2.

What we provide on the exam cover page

R = 0.08206 L atm/mol K

R = 62.36 L torr/mol K

R = 0.08314 L bar/mol K

R = 8.314 J/mol K

NA = 6.022 × 1023 mol-1

1 atm = 1.01325 × 105 Pa

1 atm = 760 torr

1 atm = 14.7 psi

1 bar = 105 Pa

1 in = 2.54 cm

1 lb = 453.6 g

1 gal = 3.785 L

\(\rho_{\rm water} = 1.00\) g/mL

\(\rho_{\rm mercury} = 13.6\) g/mL

And now, once again, for your enjoyment...

The 19 Learning Outcomes for Gases

Students will be able to…..

  1. Describe pressure from a macroscopic and microscopic perspective.
  2. Relate Boyles, Charles', and Avogadro's gas laws to observations of gas behavior.
  3. Calculate the values for state functions (n, V, T, P) using the ideal gas equation.
  4. Define the conditions of STP and SATP.
  5. Relate the number density and mass density for a given gas, including quantitative calculations such as mass, molecular weight, and density.
  6. Relate partial pressures and the total pressure as described by Dalton’s Law of Partial Pressure.
  7. Apply the concept of the gas laws to gas phase reactions.
  8. Perform stoichiometric calculations using gas properties, masses, moles, limiting reagents, and percent yield.
  9. Relate kinetic energy to the temperature of a gas.
  10. Relate temperature, molar mass, and gas velocity.
  11. Describe the effect of molar mass and temperature on the Maxwell-Boltzmann gas velocity distribution.
  12. Apply kinetic molecular theory to a variety of gas phenomena including diffusion and effusion.
  13. Calculate relative effusion and diffusion rates using Graham’s Law.
  14. Explain the quantitative relationship between state functions (n, T, V, and P) as described by kinetic molecular theory.
  15. Describe macroscopic gas behavior using a small particle model of a gas.
  16. State when the ideal gas model fails to predict the behavior of gases observed in nature and in the laboratory.
  17. Explain what the breakdown of the ideal gas law reveals about the assumptions of kinetic molecular theory.
  18. Explain the general principles of the hard sphere model and van der Waal's model of gas.

NEW! 19. Define the compressibility factor (Z) and how its value gives insight into the types of forces in between gas molecules.

You want 'em, you got 'em... The 25 Question Types for Exam 1!