Ch. 4 & 13  solution; complex ion reaction; Lewis acid / base                        test  [100 points]

 

Show your work in an organized manner, include (i) any relevant equation (or formula), (ii) conversion factor(s), (iii) put the proper units in your calculations and answer, and (iv) have the proper number of significant figures in your answer. 

 

Academic Honesty:   The answers on this test are my own and I am using only the allowed set of notes as described in the syllabus.  I have not discussed the test questions with anyone before or during the test nor have I seen the test questions prior to the exam.  If you violate any of the preceding items or do not sign, your semester grade is a F.

 

                                                                                Signature:  ___________________

 

 

1. Describe an experimental protocol, based on solubility rules, to differentiate between an aqueous solution of __; include an interpretation of your observations.   [10 points]

 

a.  Sodium sulfate versus sodium sulfide

 

b.  Magnesium nitrate versus barium nitrate

 

 

 

2.  Describe how to prepare 85.0 mL of a 275.0 mM glucose solution using __.  [10 points]

a.  Solid glucose, C6H12O6

b.  575.0 mM glucose solution

3. Excess sodium phosphate was added to 25.0 mL aqueous solution of calcium chloride, which formed 1.5 g of a precipitate.  What was the concentration of calcium ions prior to the addition of sodium phosphate ?  [15 points]=

4. Write the net ionic equation describing  __.   [15 points]

a.  Mixing aqueous solutions of sodium bicarbonate and acetic acid

b.  Adding aqueous solutions of sodium hydroxide and zinc nitrate

c. Add excess potassium cyanide to copper (II) chloride

d.  Put solid zinc into hydrochloric acid

e.  Bubble sulfur trioxide gas into water

5. Using Henry’s law, rationalize the basis of the small bubbles (i.e. it’s not boiling) seen due to heating a pot of water.   [10 points]

6.  A solution of 0.186 g of a nonelectrolyte added to 22.01 g of camphor, C10H16O, has a freezing point of 176.7 °C.  The Kf of camphor is 40.0 °C / molal and its melting point is 179.8 °C.  [20 points]

a. What is the freezing point depression by this solute of the solution ?

 

b. What is the molality of the solute in solution ?

 

c. How many moles of the solute are in the solution ?

 

d.  What is the molar mass of the solute ?

7. A solution of 125 g of benzene, C6H6, and 125 g of toluene, C6H5CH3 was heated to 100. ° C.  At 100. °C, assume that benzene’s vapor pressure is 1050. torr, while toluene’s vapor pressure is 500. torr.   [20 points]

 

a. What is the vapor pressure of the solution due to the evaporation of benzene ?

 

b. what is the vapor pressure of the solution due to the evaporation of toluene ?

 

c. what is the mole fraction of benzene in the gas phase ?