Solutions to Review #1

1. a.

b.

2. 4 mL = 0.004 L =0.004/22.4 =0.000178 moles of C₂H₆O

H₂O = 0.0007738 moles X 18g/mole = 0.014 g

3. A solid’s molecules only vibrate. But if the solid absorbs heat from its surroundings, the molecules vibrate faster. In a solid that sublimates, the molecules overcome intermolecular attractions and they begin to both rotate and translate. At this stage we have a gas.
4. No. Temperature depends on the average kinetic energy of molecules. So although the bulk of molecules have more or less the average speed, there are extremes that move either slower or faster. Also, at the same temperature, molecules of a lower molar mass will, on the average, move faster than those of a higher molar mass. Remember K.E. = 0.5 mv².

5. P₂=350/300P₁. Why? Because if volume and moles are constant, then P₁/T₁ = P₂/T₂ from combined gas law. For ideal gases, pressure is directly proportional to absolute temperature (Kelvin) if volume remains constant.

6.

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Created:April/6/1996; Updated: Jan/05/2010