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Midterm 1 Material
Midterm 2 Material
Lewis structures + resonance + shapes + polarity
Orbital Theories
100
Convert 0.0030 mm to nm
3.0 x 103 nm
100
A 355-mL soft drink sample contains 0.133 mol of sucrose (table sugar). What is the molar concentration of sucrose in the beverage?
0.375M
100
A molecule with an odd number of electrons is ALWAYS:
(a) paramagnetic
(b) diamagnetic
(c) It can be either
a
100
draw the resonance hybrid form of a nitrate ion
Drawn on board
100
Which statement regarding stable heteronuclear diatomic molecules is false?
(a) All have bond orders greater than zero.
(b) The antibonding molecular orbitals have more of the character of the more electropositive element than of the more electronegative element.
(c) Their molecular orbital diagrams are more symmetrical than those of homonuclear diatomic molecules.
(d) The bonding molecular orbitals have more of the character of the more electronegative element than of the less electronegative element.
(e) The greater is the difference in energy between two overlapping atomic orbitals, the more polar the resulting bond is, due to electrons occupying the resulting bonding molecular orbital.
(c)
200
Carbon monoxide has ten bonding electrons and four anti-bonding electrons. Therefore it has a bond order of
3
200
Calculate the molarity of 6.52 g of CoCl2 dissolved in an aqueous solution with a total volume of 75.0 mL.
0.674 M
200
Predict the group in the periodic table in which an element with the following ionization energies would most likely be found.
1st IE = 786 kJ/mol
2nd IE = 1577
3rd IE = 3232
4th IE = 4355
5th IE = 16,091
6th IE = 19,784
Group 5A
200
Draw all resonance forms of a sulfate ion
If there is a most favorable resonance form, circle it
drawn on board
200
Give the shape that describes each hybrid orbital set:
(a) sp2
(b) sp
(a) trigonal planar
(b) linear
300
- What is the expected electrical conductivity of the following solutions?
(a) NaOH(aq)
(b) HCl(aq)
(c) C6H12O6(aq) (glucose)
(d) NH3(l)
(a) high conductivity (solute is an ionic compound that will dissociate when dissolved);
(b) high conductivity (solute is a strong acid and will ionize completely when dissolved);
(c) nonconductive (solute is a covalent compound, neither acid nor base, unreactive towards water);
(d) low conductivity (solute is a weak base and will partially ionize when dissolved)
300
A sample of magnesium is found to contain 78.70% of 24Mg atoms (mass 23.98 amu), 10.13% of 25Mg atoms (mass 24.99 amu), and 11.17% of 26Mg atoms (mass 25.98 amu). Calculate the average mass of a Mg atom.
24.31 amu
300
Calculate the wavelength of emitted photon when an electron goes from n = 3 to n =1
λ = 1.025×10-7 m
300
Which of the following molecules or ions contain polar bonds?
a. O3
b. O22-
c. NO3-
d. CO2
e. H2S
f. BH4-
g. S8
c,d,e,f
300
Draw the Lewis structures for CO2 and CO, and predict the number of σ and π bonds for each molecule.
a. CO2
b. CO
2 sigma 2 pi
1 sigma 2 pi
400
Complete the following reaction and show the complete and net ionic equations
calcium hydroxide + iron(III)chloride-->
.Molecular: 3 Ca(OH)2 (aq) + 2 FeCl3 (aq) 3 CaCl2 (aq) + 2 Fe(OH)3 (s)
Total Ionic: 3 Ca2+ (aq) + 6 OH¯ (aq) + 2 Fe3+ (aq) + 6 Cl¯ (aq) --> 3 Ca 2+ (aq) + 6 Cl¯ (aq) + 2 Fe(OH)3 (s)
Net Ionic: Fe3+ (aq) + 3 OH¯ (aq)--> Fe(OH)3 (s)
400
A compound is found to contain 26.56% potassium, 35.41% chromium, and the remainder oxygen. Find its empirical formula.
K2Cr2O7
400
Which of the following has two unpaired electrons?
- Mg
- Si
- S
- Both Mg and S
- Both Si and S.
5. both Si and S
400
Draw the Lewis structures and indicate whether or not they are polar:
NCl3
CHN
CS2
NCL3 = trigonal pyramidal, polar
CHN = linear, polar
CS2 = linear, nonpolar
400
Write the correct molecular orbital theory electron configuration and diagram for C2
1s2 *1s2 2s2 *2s2 
2py2 2pz2
500
Calculate the enthalpy of reaction for:
CH4 + Cl2 -->CCl4 + HCl
C-H = 413 kJ/mol
C-Cl = 339 kJ/mol
Cl-Cl =243 kJ/mol
H-Cl = 432 kJ/mol
-460 kJ/mol
500
Aluminum and hydrogen chloride react to form aluminum chloride and hydrogen gas
Write and balance the equation
How many grams of aluminum metal are needed to produce 3.33 moles of aluminum chloride?
2 Al + 6 HCl --> 2 AlCl3 + 3 H2
89.91 g Al
500
- What is the energy in joules and electron volts of a photon of 420-nm violet light?
- What is the maximum kinetic energy of electrons ejected from calcium by 420-nm violet light, given that the workfunction for calcium metal is 2.71 eV?
1 ev = 1.6 x 10-19 J
4.74×10−19J
2.96eV.
KEe=hν–Φ=2.96eV–2.71eV=0.246eV.
500
Draw the Lewis structure of nitrous acid.
What are the electron pair geometries and molecular geometries of all central atoms?
What are the bond angles?
Electron pair: O: tetrahedral, N: trigonal planar
Molecular geometry: O: bent (<109 degrees), N: trigonal planar (120 degrees)
Lewis structure drawn on board
500
2C3H8(g)⟶C2H4(g)+C3H6(g)+CH4(g)+H2(g)
For each of the four carbon compounds, do the following:
(a) Draw a Lewis structure.
(b) Predict the geometry about the carbon atom.
(c) Determine the hybridization of each type of carbon atom.
C3H8: tetrahedral (all sp3)
C2H4: trigonal planar (sp2)
C3H6: trigonal planar (1&2) (sp2) and tetrahedral (3) (sp3)
CH4: tetrahedral (sp3)