Download 2A Final Exam Review Worksheet

2A Final Exam Review Worksheet
General Concepts (not meticulously exhaustive):
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Density = mass / volume
Terms: compound, mixture, element
Isotopes
o Isotope = occurs when the number of neutrons vary for a particular element. The number of
protons do not vary.
o Given any two of these variables, be able to solve for the third: weighted average atomic mass,
isotopic mass, fractional abundance
Counting protons, neutrons, and electrons in elements and ions
Composition problems
o Percent mass
o Empirical formulas, molecular formulas
Nomenclature: aqueous acids, molecular compounds, ionic compounds, straight-chained alkanes
Balancing reactions
o By inspection
o Redox: reactions where oxidation states change
§ Oxidized, Reduced, Ox Agent, Red Agent
§ Half-Reaction Method of balancing
Stoichiometry
o For individual molecules
o Reactions
§ Stoichiometric calculations
§ Writing reactions (net ionic, double, single, combustion, combination, decomposition,
neutralization, precipitation)
o Limiting reaction
§ Stoichiometry problems where information related to moles is given for 2 or more
reactants
§ Combo with % Yield
§ Amount unreacted
o Titrations
§ Stoichiometry problems involving molarity, M
§ Moles needed to neutralize
o Percent Yield
Dilution (M1V1 = M2V2 & n1 = n2)
Solubility Rules (will it precipitate?)
Strong Acids and Bases vs. Weak
Gas Laws
o Combined Gas Laws (including Charles, Boyle, etc.)
o Ideal Gas Law (& d = m/V & M = m/n)
o Dalton’s Law (mixture of 2 or more gases)
§ General Problem
§ Dalton over water
Kinetic Theory of Gases Assumptions & Concepts
o 5 assumptions
o Temperature is proportional to kinetic energy. Two molecules at the same temperature will have
the same average kinetic energy.
o If two molecules are under the same conditions, the heavier molecule will travel slower
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Energy equations
o c = λν
o E = hν = hc/λ
o Rydberg equation (also know how to use it to calculate ionization energy, I)
Quantum Numbers
o Given a quantum number, determine all possible quantum numbers
o Determine if a set of quantum numbers is allowable
o Determine what set of quantum numbers are associated with a particular electron in an atom.
Electron configuration
o spdf shorthand notation
o Orbital electron energy level diagram especially when generating an MO diagram or
hybridization diagram.
Periodic Trends
o Radius, Zeff, shielding/screening, I, EA, EN
o Know trends for elements, ions
o Understand how trends of Zeff and screening/shielding relate to other trends such as r, I, EA, EN,
etc.
o Know shielding trend for orbitals (spdf)
o Determine ΔEN (also most ionic, most covalent, most polar, most nonpolar) for a bond from
Periodic Table
Problems based on Lewis Structures
o Draw Lewis structures and resonance structures
o Find formal charge, ideal bond angles, electronic geometry, molecular geometry, polarity, BO
(remember resonance), relative BL, relative BE, hybridization, number of σ bonds, number of π
bonds
MO diagrams
o Draw diagram, label energy levels, fill in electrons for any homonuclear diatomic molecule or ion
(no larger than Ne2)
o Understand concepts behind σ and π bonds
o Paramagnetic or diamagnetic
o Calculate BO
Hybridization
o Determine hybridization for any central atom
o Draw hybridization schematics for sp, sp2, and sp3 for atoms (C as well as others)
o Determine what hybrid orbitals overlap to form a bond
o Determine the total number of σ and π bonds in a molecule (remember bond-line formulas)
Questions (not necessarily representative of all possible questions):
1. If the density of aviation fuel is 1.77 lb/L, how many liters must be added to a tank to give 16,131 kg
(1 kg= 2.205 lb)?
2. Count the total number of protons, neutrons, and electrons:
protons neutrons electrons
192 2+
Ir
NO+
HSO4–
3. There are two stable isotopes of supposium (Su).
Su-191 = 190.9609 u (27.30%) Su-194 = 193.9633 u (72.70%)
Compute the atomic mass of supposium.
4. Name: A. SrI2 (aq) B. CrCO3 (s) C. HBr (aq) D. HNO2 (aq) E. XeF4 (g) F. HClO G. HClO2
5. What is the charge on Z? Z(PO4)3
6. The monosaccaride ribose is found in biological systems. Combustion analysis shows that ribose
contains 40.00% carbon, 6.714% hydrogen, and 53.29% oxygen. A. Calculate the empirical formula of
ribose. B. If the molecular mass of ribose is 150.13 g/mol what is the molecular formula of ribose?
7. Reactions A. Balance: HClO4 + P4O10 → H3PO4 + Cl2O7
B.Which of the following represents a redox reaction?
i) 2 H2(g) + O2(g) → 2 H2O(l)
ii) NH3(aq) + HCl(aq) → NH4Cl(aq)
iii) 2 NaOH(aq) + CuCl2(aq) → 2 NaCl(aq) + Cu(OH)2(s)
iv) HBr(aq) + AgNO3(aq) → HNO3(aq) + AgBr(s)
v) 2 H2O2(aq) → 2 H2O(l) + O2(g)
C. Write the combustion reaction for hexane
8. S8 (s) + OH¯ (aq) → S2O32- (aq) + S2- (aq) + H2O (l)
A. What is oxidized? What is oxidizing agent? B. Balance in basic conditions.
9. For question 7A above…
A. If there is 10.0 g of P4O10, find the mass of phosphoric acid formed.
B. If there is also 10.0 g of perchloric acid, find the mass of phosphoric acid formed.
C. Considering A & B, how much of the excess reactant remains after the reaction is complete.
D. Find the number of phosphorus atoms in 10.0 g of P4O10.
E. If the mass of phosphoric acid formed was 1.00e-3, find the percent yield.
10. With 100.0 mL of an acid at 2.0 M, what final vol. is necessary in order to dilute the acid to 0.50 M?
11. 100.0 mL of 2.00 M sulfuric acid neutralizes with what mass of potassium hydroxide?
12. A. What are the products to the following reaction that occurs in solution? (NH4)2S + Al(C2H3O2)3
→ ? B. Which will ppt? Sr(NO3)2, BaSO4, BaS, AgBr, AuBr
13. What are all the strong acids and strong bases from Chp 5? Is HClO a strong acid?
14. 8.0 moles of helium gas at 1.0 atm is in a 6.0 L container at 27°C. All the helium gas is then
transferred to a 12.0 L container at 327°C. What is the final pressure?
15. 53.5 g of an ideal gas of molecular weight = 30.5 g/mol is confined at a pressure of 133 mmHg. The
density of the gas is 0.228 g/L. Compute the temperature of the gas in degrees Celsius.
16. A tank contains 480.0 grams of oxygen and 80.00 grams of helium at a total pressure of 7.00
atmospheres. A. What are the total moles of gas in the tank? B. What is the partial pressure of O2? C.
What is the partial pressure of He?
17. A. Fill in the blanks:
ni
nf
E
λ (nm)
ν (MHz)
2
3
B. Would a wavelength of 600 nm be higher or lower energy than part A?
18. Label the electrons (A, B, C) from the table in the
electron configuration below.
Electron Label
A
B
C
n
1
2
3
l
0
0
0
ml
0
0
0
ms
-½
½
½
19. Fill in the BLANKS with the correct electron configuration (spdf condensed) or correct neutral
element.
Element
Electron Configuration
Bi
1s22s22p63s23p64s23d104p65s24d105p66s15d94f14
20. Circle the correct answer in the table below.
Question:
Which element has the lower first ionization energy?
Which orbital is better at shielding (screening)?
The oxide of which element can react with both acids and bases?
Which chemical species is a better reducing agent?
Which bond is more covalent?
In the atom of phosphorus, total spin (the sum of electron spin
quantum numbers ms) is
Answer?
B
O
p
d
Ca
Al
Li
F
CO
BO
3/2
0
Which species has the smaller radius?
Na
Mg+
21. The structure of aspirin is given below.
a. Which set of hybrid orbitals best describes the (a-b) C-O bond in aspirin?
b. What is the approximate bond angle around the O labeled “a”?
c. What is the bond order of the (a-b) C-O bond?
d. Is this molecule polar or nonpolar?
e. What is the geometry around the oxygen atom labeled “a”?
f. What is the hybridization of the carbon atom marked “b”?
g. What’s the molecular formula of aspirin?
22. Draw the 2 possible Lewis structures (i.e., 2 most likely structures) of thiocyanide (SCN─). Assign
formal charges to all elements in all structures. Circles the most probable structure bases on formal
charges.
23. Fill in the following table for the best Lewis structure. Determine formal charge and oxidation state
for the underlined elements.
Electronic Molecular Bond Polar or Hybrid- Formal Oxidation Total σ Total π
Molecule
Geometry Geometry Angles Nonpolar ization Charge(s)
State
Bonds Bonds
ClF3
ClCN
BH3
XeOF4
OF2
24. Draw the energy diagram for an sp3 hybridized N atom, then fill in the electrons. Describe what
each hybridized orbital represents. 25. Draw the MO diagram for O2+ labelling all the energy levels. Determine the BO and magnetism.
26. What is the CO bond order of the carbonate ion?
Answers (hopefully they are all correct):
1. 2.01 x 104 L
2.
192
Ir2+
NO+
HSO4–
Protons
77
15
49
neutrons
115
15
48
electrons
75
14
50
3. 193.1 u
4. Strontium iodide, chromium (II) carbonate, hydrobromic acid, nitrous acid, xenon tetrafluoride,
5.
6.
7.
B.
hypochlorous acid, clorous acid
+9
CH2O, C5H10O5
A. 12 HClO4 + P4O10 → 4 H3PO4 + 6 Cl2O7
i and v
C. 2 C6H14 + 19 O2 à 12 CO2 + 14 H2O
8.
A. S or S8
B. 12 OH¯ (aq) + S8 (s) → 2 S2O32- (aq) + 4 S2- (aq) + 6 H2O (l)
9. 13.8 g, 3.25 g, 7.6 g, 8.49e22 atoms, 0.0308%
10. 400.0 mL
11. 22.4 g
12. A. 3 (NH4)2S (aq) + 2 Al(C2H3O2)3 (aq) → 6 NH4C2H3O2 (aq) + Al2S3 (s)
B. aq, s, aq, s , aq
13. SA: HClO3, HClO4, HCl, HBr, HI, HNO3, H2SO4
SB: KOH, NaOH, LiOH, RbOH, CsOH, Ca(OH)2, Sr(OH)2, Ba(OH)2
HClO is a weak acid
14. 1.0 atm
15. 12°C
16. 34.99 mol, 3.00 atm, 4.00 atm
17. A.
ni
nf
2
3
B. Higher
18. A = #2, B = #3, C = #11
19.
Element
Bi
Pt
E
3.03e-19
λ (nm)
656
ν (MHz)
4.57e8
Electron Configuration
[Xe]6s25d104f146p3
1s22s22p63s23p64s23d104p65s24d105p66s15d94f14
20. B, p, Al, Li, CO, 3/2, Mg+
21. sp2 (C) – sp3 (O), 109.5, 1, polar, bent, sp2, C9H8O4
22.
0 0 -­‐1 -­‐1 0 0 +1 0 -­‐2 (not good!) 23.
Molecule Electronic Molecular
Bond Polar or Hybrid- Formal Oxidation
σ Bonds π Bonds
Angles Nonpolar ization Charge
State
ClF3
TrigonalBipyramidal
T-shape
90º
polar
sp3d
0
-1
3
0
ClCN
Linear
Linear
180º
polar
sp
0
-3
2
2
Trigonal
Trigonal
Planar
Planar
120º
nonpolar
sp2
0
-1
3
0
Square
Pyramidal
90º
polar
sp3d2
0
+6
5
1
Bent
109.5º
polar
sp3
0
+2
2
0
BH3
XeOF4 Octahedral
OF2
Tetrahedral
24.
E 2p sp3 2s unhybridized hybridized The first hybridized orbital represents the lone pair of electrons on N. The next three hybridized orbitals
represent potential sigma bonds with other elements.
25. BO = 2.5, paramagnetic (MO diagram below)
26. 1.33
σ2p* ↑
↑
↓ ↑
π2p* ↑ ↑
↑↓ 2p ↑↓ π2p ↑↓ E σ2p ↑↓ σ2s* ↑↓ ↑↓ 2s 2s ↑↓ σ2s ↑
2p ↑