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CHEM 111 Your full name (PLEASE PRINT) ______
First hour test page 1 of 5
September 24, 2010 Your scheduled class hour (please circle) B hr E hr
Make sure your test has FIVE pages---notify us immediately if it does not. Do NOT detach pages from the staple. You may use a writing implement, hand-calculator, the pink data page (if necessary), and your Periodic Table (unmarked, honor code) as obtained in this course. NO scratch paper is permitted! As requested of the faculty by the Student Executive Committee, students must sit in every other seat during the test. Your work must be shown clearly on all problems, and final answers must be expressed in scientific notation. Pay attention to dimensions!! When blanks for answers are provided, write your answer to be graded in the blank---I may not grade answers written in other locations!
It is your responsibility to make sure the test you turn in has 5 securely fastened pages.
PRE-PLEDGE: I will neither give nor receive any unacknowledged aid on this test.
Signed, ______
1. (24 pts) Show by appropriate formula(s) what species are present after each of the following bulk substances are mixed (individually) with water. Clearly distinguish between ions, molecules, and solids in the final aqueous mixtures.
potassium hydrogenphosphate HClO4
HI NiCl2
Silver Sulphite Co(OH)2
Barium Hydroxide HgI2
2.(2 pts) Circle one: true or false: It is observed that when bulk FeCl3 is added to water, it dissolves. This may be explained by the fact that Fe3+ is a hard Lewis acid and thus has a more favorable interaction with the hard Lewis base, H2O, than it does with the relatively soft Lewis base, Cl-.
3.(2 pts) Circle one: true or false: When potassium metal, K(s), is placed in water, a violent reaction is observed. During this reaction, H2(g) is evolved and the solution becomes basic due to the presence of OH - This is an example of a Redox reaction.
4. (2 pts) Circle one: true or false: The potential energy due to the interaction of one positively charged particle and one negatively charge particle increases as the particles are brought closer together.
5. (8 pts) Briefly and accurately define the following terms:
(a) Ligand: ______
(b) Bronsted Acid: ______
(c) Lewis Base: ______
(d) Formal Charge:______
6. (2 pts) What is the oxidation number of the ionic complex, b ? ______
7. (1 pts) What is the oxidation number of the O-atom in the ionic complex shown above? ______
8. (1 pts) What is the oxidation number of the Cl-atom in the ionic complex shown above? ______
9. (8 pts) Consider the reaction occurring in water given below (note: Sn and Ag are the central atoms in the complexes in which they are present):
Give the oxidation numbers of:
Sn in ______Sn in ______H in ______Ag in ______
What is the reductant species?______What is the oxidant species?______
10. (8 pts) In the spaces provided below, write the number of significant figures:
150.02______150 x 102______.00008______6.022x1023______
11. (6 pts) (a) .23 g + 8.8 g = ______(b) 45 m - .011 km = ______
(c) ______
12 (4 pts) A graduated cylinder contains 57.20 mL of a liquid, T. The weight of the cylinder with the liquid is 147.383 g, and the weight of the empty cylinder is 83.1 g. What is the density of the liquid, T?
Answer______
13. (24 pts) The following pairs of substances were first, as separate substances, mixed with water. Then the two aqueous mixtures were combined with thorough stirring. For each pair:
(a) & (b) show by appropriate formula(s) what would be present in the separate mixtures;
and then
(c) deduce and write the balanced chemical equation for the reaction(s) which occur(s) when the
two mixtures are combined. If no reaction occurs upon mixing, write “NR” (No reaction!)
NiSO4 and four equivalents of NaCN
(a) (b)
(c)
13 (continued)
and Hydrobromic acid
(a) (b)
(c)
sodium nitrate and hydrogen iodide
(a) (b)
(c)
PbCl2 and HOAc
(a) (b)
(c)
and barium hydroxide
(a) (b)
(c)
Potassium nitrite and magnesium hydroxide
(a) (b)
(c)
14. (4 pts) Circle the letter of the one best answer:
For a mixture analyzed by gas chromatography, the compound least strongly attracted to the mobile phase will spend the ______time adsorbed on the stationary phase and will move more______through the column.
(a) least, slowly (b) least, quickly (c) most, slowly (d) most, quickly
For a mixture analyzed by thin layer chromatography, the compound most strongly attracted to the stationary phase will spend the ______time adsorbed on the stationary phase and have the ______Rf value.
(a) least, smallest (b) least, largest (c) most, smallest (d) most, largest
15 (2 pts) Use the figure at right to answer the following two questions:
This is a mass spectrum of (circle one):
C2H4O2 (acetic acid)
or CH2O2 (formic acid)
or CH2O (formaldehyde).
What is the source of the peak with 100% relative abundance?______
Bonus question (5pts): The fluoridation of city water supplies has been practiced in the United States for several decades. It is done by continuously adding sodium fluoride to water as it comes from a reservoir. Assume you live in a medium-sized city of 150,000 people and that 660 L of water is consumed per person per day. What mass of sodium fluoride (in kg) must be added to the water supply each year to have the required fluoride concentration of 1 kg of fluoride per 1 million kg of water? Note that there are 365 days per year and that the density of water is 1.00 g per cm3. Show your work.
Answer______
PLEDGE: I have neither given nor received any unacknowledged aid on this test.
Signed, ______