Formulas, Constants, and Conversion Factors
NA = 6.022 x 1023
1 lb = 454 g
1 kg = 2.205 lb
1 in = 2.54 cm
39.37 in = 1 m
1.057 qt = 1 L
1 gal = 3.785 L
1 atm = 760 mm Hg = 760 torr = 14.7 psi
=101325 Pa
Combined Gas Law
P1V1 = P2V2
n1T1 n2T2
ºC = (ºF – 32) 5/9
ºF = (ºC x 9/5) + 32
K = ºC + 273
Heat of a temp. change: ∆HTC = m · c · ∆T
Heat of a phase change: ∆HPC = m · HPC
∆G = ∆H - T∆S
density = mass
volume
Expressed as
a decimal
Dalton’s Law
PT = P1 + P2 + P3 (P1 = %1 · PT)
Dilutions
C1V1 = C2V2
% yield =
actual yield
x
theoretical yield
100
Acids and Bases
NaVa = NbVb
Ideal Gas Law
PV = nRT
R = 0.082057 L · atm / K · mol
Ka = [H3O+] [A-]
[HA]
pH = -log [H3O+]
Kw = [H3O+] [OH-] = 1.00 x 10-14
Molar volume of a gas = 22.414 L at STP
pH + pOH = 14.00
Molarity (M) = moles of solute
liters of solution
v/v% =
Molality (m) = moles of solute
kg of solvent
m/m% =
volume of solute (mL)*
volume of solution (mL)*
mass of solute (g)*
mass of solution (g)*
x 100%
x 100%
*note: units may vary as long as numerator & denominator match.
Normality (N) = equivalents of solute
liters of solution
m/v% =
Osmolarity = total moles of solute particles
liters of solution
= (M) x (# particles)
Equivalent wt of an ion = molar mass of ion (g)
# of charges n the ion.
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mass of solute (g)
x 100%
volume of solution (mL)
Name
Unit 3 Exam (Spring 2015)
CHEM 305 ID:
_____________________
CHEM 305 (V. Alino)
Date : ___________________________________
B
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. (2 pts ea)
1) Which substance produces carbon dioxide and water upon reaction with an acid?
A) H2 C2 O4
B) NaCH3 CO2
C) NH4 NO3
D) MgCO3
2)
C5 H5 N + H2 CO3
C5 H6 N+ + HCO3 -
In the reaction shown, the conjugate acid of HCO3 - is
A) H2 CO3
E) C8 H18
B) H3 O+
.
C) HCO3 -
D) C5 H6 N+
E) C5 H 5 N
D) 0.80 Osmol
E) 0.40 Osmol
3) A Bronsted-Lowry base is a substance which
A) accepts protons from other substances.
B) produces hydrogen ions in aqueous solution.
C) accepts hydronium ions from other substances.
D) produces hydroxide ions in aqueous solution.
E) donates protons to other substances.
4) What is the osmolarity of a 0.20M solution of K2 SO4 ?
A) 0.20 Osmol
B) 0.60 Osmol
C) 0.10 Osmol
5) Hydrochloric acid is a strong acid in water because it is
A) completely dissociated into hydronium ions and chloride ions.
B) very able to hold onto its hydrogen ion.
C) only slightly dissociated into ions.
D) very soluble soluble.
E) concentrated.
6) The half-life of sodium-24 is 15.0 hours. What percentage of a sample of sodium-24 remains after 60.0 hours?
[fraction left = (0.5)n]
A) 0.00%
B) 6.25%
C) 25.0%
D) 3.13%
E) 12.5%
7) Which intermolecular forces of attraction are present in CH3 F? (The electronegativities of the elements are
C=2.5, H=2.1, F=4.0)
A) dipole-dipole forces
B) dipole-dipole and London dispersion forces
C) H-bonding and London dispersion foces
D) dipole-dipole, H-boncing, and London dispersion forces
E) None of these statements is correct.
8) Calculate the hydrogen ion concentration in a solution with pH = 6.35.
A) 6.35 M
B) 4.5 × 10-7 M
C) 7.65 M
D) 0.80 M
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E) 2.2 × 10-8 M
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9) If the concentration of OH- in an aqueous solution is 1.4 × 10-7 M, the concentration of H3 O+ is
A) 7.1 × 10-8 M
B) 1.3 × 10-8 M
C) 7.1 × 10+6 M
D) 1.0 × 10-7 M
.
E) 1.4 × 10-7 M
10) Which description best fits a gas?
A) Definite shape and volume; strong intermolecular attractions
B) Volume and shape of container; strong intermolecular attractions
C) Volume and shape of container; no intermolecular attractions
D) Definite volume; shape of container; moderate intermolecular attractions
E) Definite volume; shape of container; weak intermolecular attractions
11) Which product is formed by beta emission (0 -1 e) from polonium-208? The atomic number of polonium is 84.
A) 212
B) 209
C) 208
D) 204
E) 208
86 Rn
84 Po
85 At
82 Pb
83 Bi
12) The process of melting solid ice to liquid water is
A) endothermic; decrease
B) endothermic; increase
C) exothermic; decrease
D) exothermic; increase
E) endothermic; no change
and involves a(an)
in entropy.
13) Which measurement represents the smallest value of pressure?
A) 785 mm Hg
B) 22.0 psi
C) 755 torr
D) 0.750 atm
E) 100 kPa
14) A sample of gas has a volume of 135 mL at 0.600 atm. What would be the volume if the pressure is decreased to
0.200 atm while temperature is held constant?
A) 135 mL
B) 180 mL
C) 101 mL
D) 45.0 mL
E) 405 mL
15) In a gas mixture of 35% He and 65% O2 the total pressure is 800 mm Hg. What is the partial pressure of O2 ?
A) 65 mm Hg
B) 520 mm Hg
C) 280 mm Hg
D) 35 mm Hg
E) 100 mm Hg
16) What is the % (m/v) concentration of a solution containing 25.0 g of solute in 400. mL of solution?
A) 5.00%
B) 6.25%
C) 12.5%
D) 25.0%
E) 2.50%
17) Considering 1.0 M solutions of each substance, which contains the largest concentration of ions?
A) CH4
B) NaOH
C) FeCl3
D) K2 SO4
E) KCl
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18) How many grams are contained in one equivalent of iron (III) ion, Fe3+ ? [Mass of Fe3+ = 55.85 g/mol]
A) 0.0537 g
B) 167.6 g
C) 55.85 g
D) 18.62 g
E) 6.02 x 10 23 g
19) Which solution is the LEAST concentrated? Each choice refers to the same solute and solvent.
A) 2.4 g solute in 2 mL solution
B) 50 g solute in 175 mL solution
C) 20 g solute in 50 mL solution
D) 2.4 g solute in 5 mL solution
E) 30 g solute in 150 mL solution
20) Which solution is acidic?
A) [H3 O+ ] = 1.0 × 10 -4
B) [OH- ] = 1.0 × 10 -7
C) [H3 O+ ] = 1.0 × 10 -10
D) [OH- ] = 1.0 × 10 -4
E) [H3 O+ ] = 1.0 × 10 -7
CONCEPTS and DEFINITION OF TERMS. For TRUE/FALSE questions, write 'A' on your scantron if the
statement is true and 'B' if the statement is false. (3 pts ea)
21)
Liquids with a low viscosity have high intermolecuar forces of attraction.
22)
As the concentration of solute particles goes up, the freezing point of a solution goes down.
23)
If a hypotonic solution is added to the bloodstream, blood cells will be likely to swell.
24)
The conversion of a gas to a liquid to a solid is favored by (tends to be spontaneous in terms of) entropy but
disfavored by (tends to be non-spontaneous in terms of) enthalpy.
25) _____________The quantity of heat needed to completely melt a solid once it has reached its melting point.
A. Heat of vaporization
B. Heat of fusion
C. Specific Heat
26) ______________ The liquid in which another substance is dissolved.
A. Solvent
B. Solute
C. H2O
27) _______________The substance formed by gaining H+ from an acid.
A. Conjugate acid
B. Conjugate base
28) _______________A solution that contains more than the minimum amount of dissolved solute; a non
equilibrium situation.
A. unsaturated solution B. saturated solution
C. supersaturated solution
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SHORT ANSWER. C H O O S E T H E C L O S E S T V A L U E T O Y O U R A N S W E R .
29) What is the molarity of a solution prepared by dissolving 0.850 grams CaCl2 [Molar Mass =110.98 g/mol] in
enough water to make 500. mL of solution? (6 pts)
A) 296 M
B) 74.0 M
C) 0.300M
D) 0.0140M
E) 0.667 M
F) 0.00338M
30) A sample of helium has a volume of 485 mL at 47.0°C and 750 mm Hg. The temperature is lowered to 21.0°C
and the pressure to 525 mm Hg. What is the new volume? (5 pts)
B) 640. mL
C) 310. mL
D) 0.00270 mL
E) 0.00160 mL
A) 750. mL
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31) How many mL of 0.140 M NaOH are needed to neutralize 50.00 mL of a 0.130 M solution of H2 SO4 ? (5 pts)
A) 90. mL
B) 54 mL
C) 45 mL
D) 27 mL
5
E) 23 mL
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EXTRA CREDIT:
32. How many kcal of heat are required to warm 34g of water from 50°C to its boiling point of 100°C and to
convert it to steam. The specific heat of water is 1.00 cal/g °C and the heat of vaporization is 540. cal/g (6 pts)
A) 30. kcal
B) 25. kcal
C) 20. kcal
D) 15. kcal
E) 10. kcal
33. Calculate the pH of a buffer that is 0.168 M HClO and 0.089 M ClO-. The Ka for HClO is 2.9 × 10-8 . (4 pts)
A) 8.0
B) 7.0
C) 6.0
D) 5.0
E) 4.0
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