Name:  _____________________                              date:  __________________               period: _______

Ch. 15 & 16 solution & thermodynamics        test                              90 points                      honors chemistry

In problems involving any calculation, 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.

  1.  Ethanol, C2H5OH, has a melting point of – 114 ºC and a boiling point of 78 ºC.  It’s specific heat is 111, 112, and 78 J / (mol K) for solid, liquid, and gas, respectively, while its ΔH(fusion) and ΔH(vaporization) is 4.9 and 38.6 kJ / mol, respectively.  How heat is needed for 35.0 grams of ethanol at 25.0 ºC to 100.0 ºC ?  [20 points]

2. Based on thermodynamics, estimate the boiling point of benzene, C6H6 ?  [hint:  ΔS(boiling) = 96.4 J / (mol K); 10 points]

3. What is ΔS (i.e. positive, negative, zero, or ambiguous) for the reaction ___; justify / rationalize your answer.  [15 points]

a. freeze water

b. condense benzene

c. dissolve glucose, C6H12O6, a polar compound in water

4. Describe how to prepare 125 mL 275 mM glucose using ___.  [20 points]

a. Solid glucose and water

b.  750 mM glucose

5.  What is the molarity of 5.0 % glucose (by mass) ?  [10 points]

6. What is the molar mass of epinephrine based on the following information ?  A 0.64 grams of epinephrine in 36.0 g of carbon tetrachloride raises the boiling point by 0.49 ºC; the boiling point of carbon tetrachloride is 76.8 ºC and the value of Kb is 5.02 ºC / molal.  [15 points; based on HW 13.51]