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Lewis Acid & Base, Increasing Entropy, Heat of Vaporization, Osmotic Pressure

1.) In the reaction CaO(s) + SO2(g) YEILDS CaSO3(s),

Which is correct:
O2- acts as a Lewis base, and SO2 acts as a Lewis acid.
Ca2+ acts as a Lewis base, and SO42- acts as a Lewis acid.
SO42- acts as a Lewis base, and SO2 acts as a Lewis acid.
SO2 acts as a Lewis base, and O2- acts as a Lewis acid.
SO2 acts as a Lewis base, and Ca2+ acts as a Lewis acid.

2.) Arrange the following substances in the order of increasing entropy at 25°C.
HF(g), NaF(s), SiF4(g), SiH4(g), Al(s)
lowest → highest

3.) The compound methylchloride, CH3Cl, has a vapor pressure of 100 mmHg at 210 K and 10 mmHg at 181 K. Calculate the heat of vaporization of CH3Cl using the Clausius-Clapeyron equation. (please put answer in J/mol) Explain in very simple terms.

4.) What is the osmotic pressure of a solution that contains 13.7 g of propyl alcohol (C3H7OH) dissolved in enough water to make 500. mL of solution at 27°C? (please put answer in atmospheres) Explain in very simple terms.

Solution Preview

1.) In the reaction CaO(s) + SO2(g) --------> CaSO3(s),

Which is correct:
O2- acts as a Lewis base, and SO2 acts as a Lewis acid.
Ca2+ acts as a Lewis base, and SO42- acts as a Lewis acid.
SO42- acts as a Lewis base, and SO2 acts as a Lewis acid.
SO2 acts as a Lewis base, and O2- acts as a Lewis acid.
SO2 acts as a Lewis base, and Ca2+ acts as a Lewis acid.

A compound that has an unshared electron pair on the central atom is a Lewis base. It reacts by making available an electron pair that can be shared by other species. In other words, a base is any species that can make available or donate a share in an electron pair, while an acid is a species that can accept a share in an electron pair.

In this reaction, Ca+2 is a spectator ion. Notice, we can remove it since it doesn't change in oxidation state at all. Now, we've got this:

O-2 + SO2 --------> SO3-2

This looks simpler, and should help us figure out what's going on. Clearly, the O-2 is donating its extra electron pair to SO2 forming SO3-2. Therefore, O2- acts as the Lewis base, and SO2 acts as the Lewis acid. ...

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