18. (4 points) Draw all lone pairs on the structure below. Then, draw one resonance structure including all lone pairs.  (WCSU24.[x])    Enter the total number of lone pairs below:

14. (WCSU24.[x], 14 points) Aqueous solutions of ammonia are commonly used for cleaning.  a.  Draw a hydrogen bond between water (H2O) and ammonia (NH3).  Clearly label the hydrogen bond donor and acceptor on your drawing.   b. Besides the hydrogen bond, what other IMFs are present between water and ammonia?   c.  Would you predict that water and ammonia are miscible or immiscible? What about water and hexane (C6H14)?  Explain one of your answers   Give the number of hydrogen bond donors in ammonia in the box below.

25.  (WCSU24.[x]) Hot air is less dense than cold air and this is the reason that hot air balloons float! A hot air balloon on a cool summer morning is filled with air to a volume of 2.80 x 106 L and warmed to 195 °F (90 °C).  A hot air balloon must be inflated to a volume of approximately 3.10 x 106  L in order to float in air. a. (4 points) At constant pressure, provide a molecular-level explanation of the relationship between temperature and volume of a gas.   b.  (6 points) Calculate the temperature the gas must be (in °C) in order to float.   Enter the temperature of the gas below.

21.  (WCSU24.[x]) The ocean is said to contain one hundred trillion million dollars of gold (Au) in the form of gold(III) chloride.  For decades, chemists (and wannabes) have attempted to precipitate gold from seawater, albeit unsuccessfully.  One method would be to form an insoluble gold salt. Then, by a redox reaction, reduce the gold ions to pure gold ($$$!). a.  (6 points) In theory, sodium hydroxide could be used to precipitate gold from seawater.  Write the net ionic equation for the reaction below. Start with the complete ionic equation and identify spectators. AuCl3(aq)    +   3 NaOH (aq) ⟶  Au(OH)3 (s)     +    3 NaCl (aq)   b.  (4 points) Provide an alternative anion to hydroxide that could be used to precipitate gold in a similar reaction.  Write the formula of the insoluble product.  Explain in a few words how you selected the ion.   c. (12 points) You want to test the reaction in the lab before you head out to the ocean.  Calculate the mass (in g) of solid gold hydroxide (MW = 247.99 g/mol) that would form if 30 mL of a 0.200 M AuCl3 solution was mixed with 0.75 g of solid NaOH (MW = 40.0 g/mol). SHOW ALL WORK.   d.  (5 points) Calculate the percent yield if 0.98 g of precipitate are formed. (If you are unable to reach an answer in part c, you may use 3.0 g as the theoretical yield.)   Enter the percent yield in the box below.

(WCSU24) We often use theory (valence bond, hybridization, resonance, etc.) to explain experimental data. When resonance (delocalized pi bonding) is present in a structure, what you see is not always what you get.  In the structure shown, the bond angles about nitrogen are 120 degrees.     Based on this information, give the following information: a. Molecular geometry about the nitrogen atom: [blank1] b. Hybridization of the nitrogen atom: [blank2] c. Name type of orbital holds the lone pair: [blank3]

22.  (WCSU24.[x], 8 points) You are designing a new brand of hot pack using CaCl2 and water. The thermochemical equation of the dissolution process is shown below.   CaCl2(s)      

17. Sketch the plot below and draw the curve you would expect for the successive ionization reactions of beryllium. (You do not need to indicate specific IE values.) (WCSU24, 4 points)  IE1         Be(g) 

14. (WCSU24.[x], 8 points) Draw the complete Lewis structures (including lone pairs and formal charges) for the following molecules/ions: a.  ClO2- b.  CH4O   Periodic Table   In the box below, enter the total number of lone pairs in the two structures (a+b).

(WCSU24) A neutral atom in an excited state has the following electron configuration: 1s2 2s2 2p6 3s2 3p5 4s2 3d2 4p1   a.  What is the identity of the atom?  (enter symbol) [blank1] b. If the excited electron relaxes to its ground state:             i. Energy will be (  absorbed  / released  /  it depends  ):  [blank2]            ii.  The sign of ΔE will be (positive  / negative  /  neither):  [blank3]   c.  What is the ground state electron configuration (use core notation)? [blank4] d.   How many unpaired electrons are there in the ground state atom? [blank5] e.   Give one set of possible quantum numbers for an electron in a 3s orbital.           n = [blank6], l = [blank7], ml = [blank8], ms = [blank9]   Periodic Table

(WCSU24) From the dropdowns, identify whether the compound contains ionic bonds, covalent bonds, or both. a)  SiO2  [drop1] b) cobalt(II) bromide   [drop2] c)  sulfur hexafluoride  [drop3] d) CaCO3 [drop4]    Periodic Table