Redox Reactions

substance in a redox reaction that gains electrons

Contains the atoms that are reduced

oxidizing agent

the complete or partial gain of electrons or the loss of oxygen

reduction

these ions do not change oxidation number or composition during a reaction

spectator ions

a positive or negative number assigned to an atom according to a set of arbitrary rules

oxidation number

the complete or partial loss of electrons or the gain of oxygen

oxidation

the balancing of a redox reaction by comparing the increases and decreases in oxidation numbers

oxidation-number-change method

the chemical changes that occur when electrons are transferred between reactants

oxidation-reduction reactions

a method of balancing redox reactions by balancing the oxidation and reduction half-reactions

half-reaction method

the substance in a redox reaction that gives up electrons

Contains the atoms oxidized

reducing agent

another name for an oxidation-reduction reaction

redox reactions

True or False

Oxidation reactions are the principal source of energy on Earth

True

True or False

Not all oxidation reactions are accompanied by reduction reactions

False

Give two examples of redox reactions

1) The burning of wood in a fireplace

2) The metabolization of food by your body

What is the unusual oxidation number of oxygen in a compound?

+1

Are double-replacement reactions redox reactions?

No, never.

Are single-replacement reactions redox reactions?

Sometimes, they can be.

Are acid-base reactions redox reactions?

Sometimes, they can be.

Explain why oxidation cannot occur without reduction, and vice versa.

In a redox reaction one element has a complete or partial loss of electrons (oxidation) therefore another element must have a complete or partial gain of electrons (reduction).

Is the corrosion of metal a redox reaction?

Yes

Loss of electrons from an atom or ion

Gain of oxygen

Example?

Oxidation

Burning

Gain of electrons by atoms or ions

Loss of oxygen

Reduction

True or False

The number of electrons lost must equal the number of electrons gained.

True

If a substance gives up the electrons readily it is known as a...?

Strong reducing agent

If a substance gains electrons readily it is known as a...?

Strong oxidizing agent

Oxidation or Reduction

Shift of electrons away from an atom in a covalent bond

(Increase in oxidation number)

Oxidation

Oxidation or Reduction

Shift of electrons toward an atom in a covalent bond

(Gain of hydrogen)

Reduction

Any change in oxidation number of an atom indicates what?

A redox reaction has taken place

True or False

The presence of salts and acids halts the process of corrosion.

False, the presence of salts and acids speed of the process of corrosion.

How does iron corrode?

Corrodes by being oxidized to ions of iron by oxygen.

Oxidation of any free element is...?

Zero

Oxidation of number of a monatomic ion is...?

Equal to the charge of the ion

True or False

Some atoms have several possible oxidation numbers.

True

In compounds, the oxidation number corresponds with what?

The element's position in the periodic table.

Aluminum's oxidation number

3+

Fluorine's oxidation number?

1-

Hydrogen's oxidation number?

1+ when combined with nonmetals

1- when combines with metals

Oxygen's oxidation number?

2- in most compounds and ions

1- in peroxides

2+ when combined with F

True or False

The oxidation numbers of elements in a compound are not written per atom.

False, they are written per atom.

The sum of the individual oxidation numbers of all atoms in the formula for a polyatomic ion is...?

Equal to the charge of the ion

The sum of individual oxidation numbers of all the atoms in a formula must equal...?

Zero