Cliffs AP Chemistry, 3rd Edition

The Outline Format

This technique is similar to the bullet format, but instead of bullets it uses the more traditional

outline style that you may have used for years: roman numerals, letters, and so on. The advan-

tages of this format are that it does not require full sentences and that it progresses in a logical

sequence. The disadvantage is that it requires you to spend more time thinking about organiza-

tion. Leave plenty of room here because you may want to come back later and add more points.

Essay 3

The boiling points and electrical conductivities of six aqueous solutions are as follows:

Solution Boiling Point Relative Electrical Conductivity

0.05 m BaSO 4 100.0254°C 0.03

0.05 m H 3 BO 3 100.0387°C 0.78

0.05 m NaCl 100.0485°C 1.00

0.05 m MgCl 2 100.0689°C 2.00

0.05 m FeCl 3 100.0867°C 3.00

0.05 m C 6 H 12 O 6 100.0255°C0.01

Discuss the relationship among the composition, the boiling point, and the electrical con-

ductivity of each solution.

Answer

3. Given: Boiling point data and electrical conductivities of six aqueous solutions, all at 0.05 m.
   Restatement: Discuss any relationships between B.P. and electrical conductivities.
   I.BaSO 4 (If you have a highlighter with you, highlight the main categories.)
   A. BaSO 4 is an ionic compound.
   B. According to known solubility rules, BaSO 4 is not very soluble.
   
   
   1. If BaSO 4 were totally soluble, one would expect its B.P. to be very close to that
      of NaCl because BaSO 4 would be expected to dissociate into two ions (Ba2+and
      SO 4 2–) just as NaCl would (Na+and C1–). The substantial difference between the
      B.P. of the NaCl solution and that of the BaSO 4 solution suggests that the disso-
      ciation of the latter is negligible.
   
   
   2. The electrical conductivity of BaSO 4 is closest to that of C 6 H 12 O 6 , an organic
      molecule, which does not dissociate; this observation further supports the previ-
      ous evidence of the weak-electrolyte properties of BaSO 4.
   
   
   
   

Part I: Introduction

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