Chem A
Final Exam Review
In-class problem-solving
1. Determine the oxidation
state of S in HSO3-.
Set your equation equal to -1 since this is
a -1 ion.
 Assign the most electronegative atom
first. In this problem it is O. O usually
has an oxidation state of -2. Since there
are 3, total = -6.
 Assign H next. H usually has an oxidation
state of +1.
 S must be +4. (+1) + (+4) + (-6) = -1

2. What are the products of the
reaction between LiOH and HF?
What type of reaction is this?
 Neutralization
reaction.
 Water and salt (LiF)
 LiOH + HF H2O+ LiF
3. How many grams of NaOH
should be added to 225g of water
to produce a 0.10m solution?
m = mol of solute/kg of water
 0.1 = x/.225
 X = .0225 mol
 .0225 mol X 40.00 g/mol = .90g
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4. How many unpaired electrons
are in the ground state of oxygen?
= 2 unpaired electrons
 Electron configuration = 1s22s22p4
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Electron dot =
O
5. Which demonstrates the
trend for increasing atomic
radius?
a. Li; Na; K or b. Ba; Sr; Ca
 a.
Atomic radius increases
as you move down a
family.
6. What is the difference
between:
Boiling/condensation
Sublimation/deposition
Melting/freezing
deposition
Solid
freezing
condensation
Liquid
melting
evaporation
sublimation
Endothermic
processes
Exothermic
processes
Gas
Gas
Melting
(sl)
Liquid
Boiling
(lg)
Solid
Heat curve – be able to label!
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1. Be sure to convert so all units are the
same.
2. This is a significant figure problem. When
adding or subtracting look at places past
decimal.
5.47g + .042g + 5.39g
=10.90g
7. Add 5.47 g, 4.2 cg and 5.39g
8. What is the total number of ions
in 2.0 mol Cu(NO3)2?

2 mol X (3 ions/1 mol) x (Avogadro’s #/1
mol)

= 3.6 x 1024ions
9. What is the correct formula
for magnesium sulfate?
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Reminders:
Write the charges of ions
The sum of the charges must equal 0 for a
neutral compound
Magnesium cation = 2+ sulfate anion= 2Need one of each
OR
Write charges and use criss-cross rule. Like
charges cancel out. Remember to reduce if
able
Answer = MgSO4
10. Write a balanced equation of
the reaction between aluminum
sulfate and calcium hydroxide.
Al2(SO4)3 + 3Ca(OH)2  2Al(OH)3 + 3 CaSO4
11. What is the empirical
formula for C4H10?
Empirical formula = simplest wholenumber ratio
 C2H5

12. A 5.0 L of krypton gas is at a
pressure of 765 mmHg. At
constant temperature what
volume will the gas occupy if the
pressure decreases to 700.
mmHg?

Boyle’s Law = P1V1 = P2V2; (765)(5.) =
(700.) (x) = 5.5 L
13. Use the following equation:
Fe2O3 + CO  Fe + CO2
What mass of Fe is formed from
1800g of Fe2O3?
 Answer = 1300g Fe (sig figs)
1. Balance equation.
2. Must have a mole:mole ratio
3. In order to achieve this you must
molar masses to convert to moles
4. Fe2O3 + 3CO  2 Fe + 3CO2
use
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FeSO4 .8H2O
4 O in iron (II) sulfate
8 O in water
Add! = 12 O
The dot just means water can be removed
– do not multiply!
14. How many oxygen atoms are
present in iron (II) sulfate
octahydrate
15. How many liters of
H2O (g) at STP will react
with one mole of H2S?
H2S + O2  H2O + SO2
Balance equation!
2H2S + 3O2  2H2O + 2SO2
Use 22.4 L = 1 mol
Answer = 22.4 L
16. A sample of ethanol required
25 kJ of energy to be heated from
20.°C to 28°C . How many grams
of ethanol were heated?
Ethanol Cp = 3.42 J/g .°C.
Q = (m)(∆T)(Cp )
 25000J = (m)(8)(3.42)
 m = 914g
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17. A weak base is
titrated with a known
concentration of a strong
acid. Sketch the titration
curve.
Based on equivalence point.
Above 7 = strong base/weak acid
At 7 = strong base/strong acid
Below 7 = weak base/strong acid
Graph on next slide
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Starting Solution: weak base
Added Standard: strong acid
14
7
1
equivalence point (below 7)
10
20
30
40
Titration curve weak base/strong
acid
B.
Remember atomic
radius! Decreases as
you go left to right,
increases as you go
down. All other trends
18.
Choose
the series of elements
are
opposite!!!
that increases in electronegativity.
a. Rb, Cs, Fr
b. N, O, F
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Sulfur
Atomic # = 16
Atomic mass = 32
proton # = Atomic # =16
Neutron# = Mass # - Atomic # = 16
Electrons = protons in a neutral atom.
Add 2 electrons to make this ion = 18
electrons
19. Calculate p+, n0, and e- in S
2-.
20. Is HSO4- acting as an
acid or a base in this
equation?
HSO4- + H2O ↔ SO4-2 + H3O+
HSO4- is the acid because it
donates a hydrogen ion (H+)
21. What is the atomic average
atomic mass of the following
isotope?
Atomic Mass
% Abundance
26
66.6
28
15.7
30
17.7
Multiply each mass by abundance (move
decimal 2 places to left)
 Add your product – do NOT divide by 3!
 Answer = 27
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22. The half-life for candium =
100 years. If 12.5% of a sample
remains, how old is the candium
sample?
3 half-lives go by
 Sample is 300 years old

23. Write the Ksp expression for
Iron (II) nitrate (s).

Ksp = [Fe2+][NO3-]2
24. What is the
H for the
reaction A B? (see diagram on
board)
Reminders:
 Products – Reactants
 If products have more energy than the
reactants, the value is positive and the
reaction is endothermic.
 If the products have less energy than the
reactants, the value is negative and the
reaction is exothermic.

25. A compound is 36.5%
sodium, 25.4% sulfur, and 38.1%
oxygen. What is the empirical
formula?
If the molecular mass is 252, what
is the molecular formula?
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% to mass
Mass to moles
Divide by smallest
Multiply until whole
= Na2SO3
26. Describe how you would
determine the density of cube of
copper 1.0 cm on each side?
How would determining density of
an irregular object differ?

D = mass/volume

L x w x h = volume; then mass object

Mass the object and then use a graduated
cylinder to determine water displacement.
27. Calculate [H3O+] for a
substance with a pH of 5.7.
[H3O] = 10-pH
 = 2.0 x 10-6
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28. What is the pH and pOH of a
solution if the [H3O+] is 3.4 x 10
5M?
pH = -log[H3O+]
 pH = 4.5
 pH + pOH = 14
 pOH = 9.5

-
29. Mineral oil dissolves in canola
oil but does not dissolve in water.
What is the reason for this?
“like dissolves like”
 Polar solutes dissolve in polar solvents and
nonpolar solutes dissolve in nonpolar
solvents
 Water is a known polar compound
 The oils must be non-polar.
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30. Name the following:
H H H
H H H
H-C - C - C-H H-C = C -C-H
H H H
H
Propane – 3 carbons, all single bonds
Propene – 3 carbons, 1 double bond
31 What is the molecular
geometry of the following?
a. BF3
b. CH4
c. NH3
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a. = trigonal planar
b.= tetrahedral
c. = trigonal pyramidal
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F
B
F
F
H
H
C
H
H
H
N
H
H
32. Which has a greater effect
on the melting point of ice?
a. MgBr2 b. CH2H5OH
c.
KCl
a. Dissociation factor is 3. the d.f. in b is
one and the d.f. in c is 2. in equal
amounts, magnesium bromide will have the
greater effect.
33. Which molecule is nonpolar?
a. CO2
b. NaCl
c. NH3

Carbon dioxide
34. What particle is omitted
when Po-210 changes to Pb206?

alpha
35. How many moles are in
236 g of NaOH?

5.90 moles
36. What is the IUPAC name for
Ni3(PO4)2?

Nickel (II) phosphate
37. How many grams of Na are
in 56 g of NaOH?
22.99/40.00 X 56g
 = 32 g
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38. Consider the following
reactants:
Cu(NO3)2 (aq) + Zn(s) 
Predict products
Balance equation
What is the oxidizing agent?
Cu(NO3)2 (aq) + Zn (s)  Zn(NO3)2(aq) +
Cu(s)
 OIL RIG
 Zn must lose electrons to form ion so it is
being oxidized. Cu 2+ is oxidizing agent
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