Name __Average 7.6/10 Scores 8-10 Good Work!! 5-7 Work on small mistakes and concepts. 0-4 Please work on moles, molar masses, and s.f. These concepts will be used over and over again in lab and lecture.

1. Reading question--write clearly, briefly, and grammatically.

Below is shown a portion of a very long polymer. In what respects does this polymer resemble a molecular compond and in what respects does it resemble an ionic compound?

This polymer resembles a molecular compound because it is held together by covalent bonds and has a fixed ratio of C:H:Cl. Although it does not contain ions, it resembles an ionic compound because the C₂H₃Cl unit is rereated in a long 1-D lattice. C₂H₃Cl resembles the formula unit of an ionc compound. (NOTE--the latter observation required a special insight or synthesis of concepts. Each exam will have one problem requiring this type of reasoning).



2. Problem--show your work clearly.

In volcanic eruptions elemental sulfer and sulfur oxides are converted to gaseous sulfur dioxide. These eruptions are one of the sources of atomospheric sulfur which ultimately contribute to production of acid rain. The eruption of Mt. Pinatubo in the Philippines in 1991 added about 25 million tons of SO₂ to the atmosphere.

Potentially Useful Data--

a) The oxidation state (O. S.) of S in SO₂ is +4 + 2(-2) = 0 so O.S. = +4

2. The number of moles of SO₂ produced by the 1991 eruption is 3.9 x 10 ¹¹ moles (2 s. f.).

25x10⁶ tons x (1000 kg/1ton) x (1000 g/1 kg)(1 mole/64.07 g) =

M SO₂ = 32.07 + 2x16.00 = 64.07 u or g/mol

1. exponents--Is your answer reasonable??? See Appendix A for math help.
2. UNITS and conversions--read over the problem and data twice before starting.
3. calculation of M SO₂
4. Avogadro's number was not needed. Beware of extra information.