Real gases
What are the two main reasons real gases deviate from ideal-gas behavior?
Real gas molecules have finite volume and experience intermolecular attractive forces.
List the five assumptions of the kinetic molecular theory of an ideal gas.
1. Particles have negligible volume.
2. Particles exert no attractive forces on each other.
3. Particles move continuously and randomly.
4. Collisions are perfectly elastic.
5. Average translational kinetic energy is proportional to absolute temperature.
What does the principal quantum number n describe?
The main energy level and general size of an atomic orbital.
What is the maximum number of electrons that can occupy one orbital? What Principle is this referring to?
2 with opposite spin, Pauli Exclusion Principle
How many sigma and pi bonds are present in a double bond and a triple bond?
Double bond: 1 σ and 1 π. Triple bond: 1 σ and 2 π
State the two ideal-gas assumptions corrected by the van der Waals equation.
Gas molecules have negligible volume, and no intermolecular attractive forces exist.
What is the difference between diffusion and effusion?
Diffusion is the spreading and mixing of gases. Effusion is the escape of gas through a tiny opening.
what are the possible l values for n=3
0, 1, 2
What does Hund's rule state about filling orbitals of equal energy?
Electrons occupy orbitals of equal energy singly, with parallel spins, before pairing.
Determine the electron geometry, molecular geometry, and bond angle of BF₃.
Trigonal planar electron geometry, trigonal planar molecular geometry, 120°.
Why can the measured pressure of a real gas be lower than the ideal-gas prediction?
Intermolecular attractions pull gas molecules toward one another, reducing the force they exert on container walls.
At the same temperature, which gas has a greater average molecular speed: helium or krypton? Explain.
Helium, Gases at the same temperature have the same average translational kinetic energy, but helium has a lower molar mass, giving it a higher average molecular speed.
List all possible mℓ values for an electron in the 4d subshell.
n = 4, ℓ = 2, and mℓ = −2, −1, 0, +1, +2.
What does the Aufbau Principle state about the order in which electrons fill orbitals?
Electrons fill the lowest-energy available orbitals before higher-energy orbitals.
Determine the molecular geometry and approximate bond angle of NH₃. How many lone pairs are present on nitrogen?
Trigonal pyramidal, approximately 107°, and 1 lone pair.
In the van der Waals equation, what do constants a and b account for?
a corrects for intermolecular attractions, while b corrects for the finite volume occupied by gas molecules.
Calculate the effusion-rate ratio r(He)/r(O₂), given M(He) = 4.00 g/mol and M(O₂) = 32.00 g/mol.
2.83. Helium effuses 2.83 times as fast as oxygen.
How many radial nodes, angular nodes, and total nodes are found in a 5p orbital?
3 radial nodes, 1 angular node, and 4 total nodes.
Write the noble-gas electron configuration of Fe²⁺
[Ar] 3d⁶
For CO₃²⁻, determine the number of sigma bonds, pi bonds, lone pairs on carbon, and the molecular geometry.
3 σ bonds, 1 π bond in an individual resonance structure, 0 lone pairs on carbon, and trigonal planar geometry with 120° bond angles.
A mixture of Ar, N2 and SO2 has a pressure of 7.85 atm. If the Ar has a mole fraction of 0.47 and N2 has a mole fraction of 0.23, what is the partial pressure of SO2?
2.4 atm
Gas A takes 40.0 seconds to effuse a fixed amount, while gas B takes 80.0 seconds for the same amount. If the molar mass of A is 16.0 g/mol, determine the molar mass of B.
64.0 g/mol.
Which set of quantum numbers is invalid?
A: n = 3, ℓ = 2, mℓ = −1;
B: n = 2, ℓ = 2, mℓ = 0;
C: n = 4, ℓ = 1, mℓ = +1.
B
Write the noble-gas electron configuration of nickel, draw its 4s and 3d orbital diagram and determine its number of unpaired electrons.
[Ar] 4s² 3d⁸. Orbital diagram: 4s [↑↓], 3d [↑↓][↑↓][↑↓][↑][↑]. There are 2 unpaired electrons.
Determine the electron geometry, molecular geometry, number of central-atom lone pairs, and approximate bond angles in SF₄.
Electron geometry: trigonal bipyramidal. Molecular geometry: seesaw. Lone pairs on sulfur: 1. Angles are distorted from 90°, 120°, and 180°.