Oxidation numbers in a group of elements.?

Question

What is the oxidation number of group 14 elements?

What is the oxidation number of group 15 elements?

What is the oxidation number of oxygen in H2O?

What is the oxidation number of the molecular ion ammonium (NH4+) in ammonium chloride (NH4Cl)?

What products are produced when a fuel is oxidized?

Could someone explain how you do these and the answers please?

Answer 1

The elements in group 14 have four valance electrons and are both metals and nonmetals.  Therefore, they can all have oxidation numbers of +4.

Carbon can have any oxidation number from -4 to +4.  Silicon can have oxidation numbers from +1 to +4.

Germanium, which is a nonmetal (metalloid), and tin and lead, which are metals, all have oxidation numbers of +2 and +4.

Group 15 is the nitrogen group.  The nonmetals in the group, N, P and As typically have oxidation numbers of +3, +5 and -3.  Antimony and bismuth have oxidation numbers of +3 and +5.

In H2O, oxygen is -2.  Each hydrogen is +1, and the sum of the oxidation numbers is zero.

The oxidation number of the ammonium ion is +1, which is the same as it's ionic charge, when it is an ion.

When a fuel burns completely, CO2 and water vapor are produced.

CxHy + zO2 --> xCO2 + (y/2)H2O  (where z = x+y/2)

Answer 2

First read the definition of "Oxidation Number" in your text,

or Wiki it.

The go here : www.webelements.com

Answer 3

Group 14 elements all have a +4 oxidation number (although some of them are also +2).

Group 15 elements are mixed; +5 is the only one they all have in common.

H2O:  H is almost always +1; there are 2 H's, so that's a +2 charge. Since water is a neutral molecule (has no charge), then oxygen must have an oxidation number of -2 to balance out the +2 from the H's.

The molecular ion ammonium (NH4) is +1; since Cl is -1, NH4 must be +1 to balancve the charge.

When a fuel is oxidized, you get CO2 and H2O. Ex.:  CH4 + 2O2 ==>  CO2 + 2H2O is the combustion of methane.