Download CHM2045 Final Exam Review, Spring 2017

CHM2045 Final Exam Review, Spring 2017
1. The combustion of 40.10 g of a compound which contains only C, H, Cl and O yields 58.57
g of CO2 and 14.98 g of H2O. Another sample of the compound with a mass of 75.00 g is
found to contain 22.06 g of Cl. What is the empirical formula of the compound? If the
molar mass of the compound is approximately 241 g/mol, what is the molecular formula
of the compound?
2. A hydrate of Na2CO3 has a mass of 4.31 g before heating. After heating, the mass
of the anhydrous compound is found to be 3.22 g. Determine the formula of the
hydrate and then write out the name of the hydrate.
3. If volumes are additive and 95.0 mL of 0.55 M KBr is mixed with 165.0 mL of
a BaBr2 solution to give a new solution in which [Br¯] is 0.65 M, what is the
concentration of the BaBr2 used to make the new solution?
4. A certain metal oxide M2O5 is 41.91% Oxygen by mass. What is the identity of the metal
M?
CHM2045 Final Exam Review, Spring 2017
5. Solvay process for manufacturing carbonate involves two steps as follows:
Step 1: H2O + NaCl + NH3 + CO2  NH4Cl + NaHCO3
Step 2: 2 NaHCO3  Na2CO3 + CO2 +H2O.
What is the percent yield of sodium carbonate in the above process if 50.0 g of NaCl were
used in Step 1 and 100.0 g of sodium carbonate were collected in Step 2?
6. Which of the following substances would be predicted to be the most soluble in hexane
(C6H14)?
(1)
(2)
(3)
(4)
(5)
Diethyl ether, CH3CH2OCH2CH3
Rubidium chloride, RbCl
Methanol, CH3OH
Benzene, C6H6
Methylene Chloride, CH2Cl2
7. You wish to titrate a 100.0 mL sample of a diprotic acid (H2A) solution that is predicted to
have a concentration of approximately 2.5 M. What volume and molarity of calcium
hydroxide would you need for your titration?
CHM2045 Final Exam Review, Spring 2017
8. Which oxide(s) form(s) acidic solutions when dissolved in water?
I.
II.
III.
IV.
MgO
SO3
Bi2O3
P4O10
9. Element X has the following valence electron configuration: [core]ns2np5. Element M has
the following electron configuration [core]ns2. What ionic compound would most likely
result from the reaction between ions of M and X?
10. A sample of methane in equilibrium with its vapor in a closed 4.0 L container has a vapor
pressure of 50.0 torr. The container’s volume is increased to 2.0 L and the liquid/vapor
equilibrium pressure is reestablished. What is the vapor pressure?
11. A metal crystallizes in a face-centered cubic lattice. The radius of the atom is 0.197 nm.
The density of the element is 1.54 g/cm3. What is this metal?
CHM2045 Final Exam Review, Spring 2017
12. What is the correct molecular geometry of the following, respectively?
I.
ICl4II.
BrF5
III.
XeCl2F2
IV.
IOCl5
V.
IF3
14. Ammonia is created in the Haber process in a rigid container at constant temperature:
3 H2 (g) + N2 (g)  2 NH3 (g)
12 moles of H2 gas are mixed with 5 moles of N2 gas. The Initial pressure exerted on the
container is 4 atm. Assuming the reaction proceeds to completion, what will be the pressure
exerted on the vessel after the reaction takes place?
CHM2045 Final Exam Review, Spring 2017
15. Which of the following ideal solutions would be predicted to have the lowest freezing
point?
I.
0.10 m Na3PO4
II.
0.35 m NaCl
III.
0.20 m MgCl2
IV.
0.15 m C6H12O6
V.
0.15 m CH3OH
17. What is the normal boiling point of a compound that has a measured vapor pressure of
24.3 torr at 273 K and 135 torr at 325 K.
18. Determine the final temperature when 20.0 g of mercury at 165.0 °C mixes
with 200.0 grams of water at 60.0 °C. (Cp for Hg = 0.14 J per gram degree
Celsius.)
CHM2045 Final Exam Review, Spring 2017
19. Which of the following compounds will exhibit resonance?
I. CO3-2
II.
O3
III.
I3IV.
HNO3
20. Use the following to calculate the lattice energy of NaCl:
Na (s)  Na (g)
Cl2 (g)  2Cl(g)
Na (g)  Na+(g) + eCl (g) + e-  Cl- (g)
Na (s) + 1/2Cl2 NaCl (s)
Hsub = 109 kJ
HBE = 243 kJ
HIE= 496 kJ
HEA = -349 kJ
Hrxn = -411 kJ
21. Here is the question: The energy from radiation can be used to cause the rupture of chemical
bonds. A minimum energy of 941 KJ/mol is required to break the nitrogen-nitrogen bond
in N2. What is the longest wavelength of radiation that possesses enough energy to break
this bond?
22. A sample of iron was dissolved in hydrochloric acid to form iron (II) chloride and hydrogen
gas. The liberated hydrogen gas was collected by displacement of water. The hydrogen
occupied 500.0 mL at 30 °C. The barometric pressure was 760 torr. What mass of iron was
dissolved? (VPH2O= 25 torr at 30 °C).