Misc.
Calculate the frequency of the light with a wavelength of 756 nm.
3.97e14 Hz
Under what two broad conditions do real gasses behave like ideal gasses.
High temperature and low pressure.
What are the four quantum numbers and how do you determine their values?
n: The principal quantum number. This is generally a given value.
l: The angular momentum quantum number. This value ranges from 0 -> n-1. (0 = s, 1 = p, 2 = d, 3 = f).
ml: The magnetic quantum number. This value ranges from +l to -l.
ms: The spin quantum number. This value is either +1/2 or -1/2 for spin up and spin down respectively.
What is Hund's Rule? What is the Pauli Exclusion Principle?
Hund's Rule: You fill electrons in sub-levels by distributing them each in their own box (orbital) with upward spin until all boxes are taken. Then assign the second electron to each box with downward spin.
Pauli Exclusion Principle: No two electrons may have the same four Quantum Numbers
What is the Octet rule? Give some examples of when it does not necessarily apply.
The octet rule states that atoms are stable when they have 8 electrons in their valence shell. It doesn't always apply with groups 1-3 or with rows where n does not equal 2.
What is the gas constant for the root mean square equation? Also, what do we have to remember about the mass variable in this equation?
R = 8.314
Mass is in kg/mol not g/mol
What is the molar mass of an unknown gas if the gas effuses through a pinhole into a vacuum at a rate of 2 mL/min, and H2 effuses at 11 mL/min.
m = 60.5 g/mol
How do you calculate: total nodes, angular nodes, and radial nodes?
Total = n-1
Angular = l
Radial = n - 1 - l
Aside from explicit exceptions, orbitals are filled in a predictable pattern/order. (T/F)
True
Draw the lewis structure of H2O.
[On board] * Oxegen as a central atom with sigma bonds to hydrogen. Oxegen has 2 lone pairs.
What is the hybridization of the valence orbitals of a molecule with tetrahedral electron geometry?
sp3 Hybridization
Find the rms velocity for (a) H2 and (b) O2 molecules at 27°C.
H2 RMS = 1.927 × 103 m s−1
O2 RMS = 4.836 × 102 m s−1
What are the possible l values for the 4p orbital?
l = 1
(its a p orbital)
Write the electron configuration for titanium.
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d²
Draw the lewis structure of BeF2
[On board] *Won't follow the octet rule. Be is central atom with single bonds to fluorines.
What is the hybridization of the valence orbitals of a molecule with octahedral electron geometry and square planer molecular geometry?
sp3d2 Hybridization
Carbon dioxide gas (1.00 mole) at 373 K occupies 536 mL at 50.0 atmosphere pressure. What is the calculated value of the pressure using
(i) Ideal gas equation
(ii) Van der Waals equation?
[Data - Van der Waals constants for carbon dioxide:
a = 3.61 L2 atm mol-2; b = 0.0428 L mol-1]
Calculate the % deviation of each value from that observed.
Ideal: 57.1 atm
% deviation = 14.2 %
Real: 49.6 atm
% deviation = (0.4/50) x 100 = 0.8%
Give the quantum numbers for the 3px orbital.
n = 3
l = 1
ml = -1
Write the abridged electron configuration for Neon.
[He] 2s² 2p⁶
For a molecule with 4 sigma bonds and 1 lone pair give the:
1. Electron geometry
2. Molecular geometry
3. Possible bond angles
4. Hybridization
1. Electron geometry = trigonal bipyramidal
2. Molecular geometry = sawhorse/seesaw
3. Possible bond angles = <90, <120
4. Hybridization = sp3d
A mixture of 40.0 g of oxygen and 40.0 g of helium has a total pressure of 0.900 atm. What is the partial pressure of each gas?
He = 0.800 atm
O2 = 0.100 atm
(i) Using Van der Waals equation, calculate the temperature of 20.0 mole of helium in a 10.0 litre cylinder at 120 atmosphere pressure.
[Data - Van der Waals constants for helium: a = 0.0341 L2 at mol-2; b = 0.0237 L mol-1]
(ii) Compare this value with the temperature calculated from the ideal gas equation.
Real: T = 696 K
Ideal: T= 731 K
Draw the radial distribution plot for the 4p orbital.
[Drawn on Board] *It will have 3 hills with each hill getting bigger as you go to the right.
Write the electron configuration for Cr.
1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ 3d⁵
Draw the resonance structures of PO43-
Give the electron and real geometry of the molecule.[On board] * One oxygen should be double bonded in each case. The single-bonded oxygens will each have a single negative charge.
e.g. = m.g. = tetrahedral