33) use PV = nRT

only thing to watch out here is that R sometimes has different values depending on what units you use for everything else

R = 8.314 J / mol * K is probably the most used

K = C + 273
K = 227+273
K = 500

so P = nRT / V
= 15.3*8.314*500 / 20



34-36 you should re-read your text if you have problems with


37) LEO the lion says GER

Losing Electrons Oxidation
Gaining Electrons Reduction

balance it first, see which side is gaining and losing electrons

the compound that is causing loss of electrons is the reducing agent
and the compound that is causing gain of electrons is the oxidizing agent

this is of course different from which compound is actually gaining / losing


38) oxidation numbering follows these rules

1) The oxidation number of an atom in the elemental state is zero.
Example: Cl2 and Al both are 0

2) The oxidation number of a monatomic ion is equal to its charge.
Example: In the compound NaCl, the sodium has an oxidation number of 1+ and the chlorine is 1-.

3) The algebraic sum of the oxidation numbers in the formula of a compound is zero.
Example: the oxidation numbers in the NaCl above add up to 0

4) The oxidation number of hydrogen in a compound is 1+, except when hydrogen forms compounds called hydrides with active metals, and then it is 1-.
Examples: H is 1+ in H2O, but 1- in NaH (sodium hydride).

5) The oxidation number of oxygen in a compound is 2-, except in peroxides when it is 1-, and when combined with fluorine. Then it is 2+.
Example: In H2O the oxygen is 2-, in H2O2 it is 1-.

6) The algebraic sum of the oxidation numbers in the formula for a polyatomic ion is equal to the charge on that ion.
Example: in the sulfate ion, SO42-, the oxidation numbers of the sulfur and the oxygens add up to 2-. The oxygens are 2- each, and the sulfur is 6+.



41) Think of the definition of a mol of any gas, should be pretty simple