Question

Homework 2 - Redox and Gas Laws 1.) Calculate the oxidation numbers of EACH atom in the compounds: note - do NOT give overall sum/total for an atom! a. NaC10;: Na _ a_ o_o_ o_ b. Na3PO; Na___ Na __ Na __P__0_ 0_ 0 PbF2 Pb __ F__ F 2.) A tank contains 22.0 grams of oxygen, 80.00 grams of helium, and 3.21 moles of hydrogen gases. The mixture has a total pressure of 7.00 atmospheres. Calculate the following. a) How many moles of O2 are in the tank? b) How many moles of He are in the tank? c) Total moles of gas in tank d) Mole fraction of each gas e) The partial pressures of each gas

Answer 1

1.

a. NaClO: Na_+1a_+5_0_2_0_2_0_2 | b. Na3PO, Na_+1 Na+1_Na_+1 p_+30_2.0_20_2 6 PbF2 Pb_+2_F_1 F-1

Explanation:

a.

The central atom of NaClO₃ is Cl. The oxidation number of Na is always +1. Except peroxide, superoxide and oxides of fluorine, the most common oxidation state of oxygen is -2.

Let us say that the oxidation state of Cl in NaClO₃ = X

Net charge of NaClO₃ = 0

Thus,

+1 + X + 3 x (-2) = 0

or, X = + 5

Hence, the oxidation number of Cl in NaClO₃ is +5.

b.

The central atom of Na₃PO₃ is P. The oxidation number of Na is always +1. Except peroxide, superoxide and oxides of fluorine, the most common oxidation state of oxygen is -2.

Let us say that the oxidation state of Cl in Na₃PO₃ = X

Net charge of Na₃PO₃ = 0

Thus,

3 x (+1) + X + 3 x (-2) = 0

or, X = + 3

Hence, the oxidation number of P in Na₃PO₃ is +3.

c.

The central atom of PbF₂ is Pb. The oxidation number of F is always -1.

Let us say that the oxidation state of Pb in PbF₂ = X

Net charge of PbF₂ = 0

Thus,

X + 2 x (-1) = 0

or, X = + 2

Hence, the oxidation number of Pb in PbF₂ is +2.