Chapter 4

Question 1

Spectator ion

Answer 1

ion that does not undergo a chemical or physical change during a reaction, but its presence is required to maintain charge neutrality

Question 2

net ionic equation

Answer 2

chemical equation in which only those dissolved ionic reactants and products that undergo a chemical or physical change are represented (excludes spectator ions)

Question 3

Reducing agent (Reductant)

Answer 3

Species that is oxidized. (Loses electrons)

Question 4

Oxidizing agent (Oxidant)

Answer 4

Species that is reduced. (Gains electron)

Question 5

Oxidation

Answer 5

Loss of electron

Increase in oxidation number

Question 6

Reduction

Answer 6

Gain of electron

Decreases in Oxidation Number

Question 7

Oxidation Number

Answer 7

The oxidation number (or oxidation state) of an element in a compound is the charge its atoms would possess if the compound were ionic.

Question 8

What are the Oxidation number guidelines?

Answer 8

The following guidelines are used to assign oxidation numbers to each element in a molecule or ion.

1. ) The oxidation number of an atom in an elemental substance is zero.
2. ) The oxidation number of a monatomic ion is equal to the ion’s charge.
3. ) Oxidation numbers for common nonmetals are usually assigned as follows:
   
   • Hydrogen: +1 when combined with nonmetals, −1 when combined with metals
   • Oxygen: −2 in most compounds, sometimes −1 (so-called peroxides, O22−), very rarely −12 (so-called superoxides, O2−), positive values when combined with F (values vary)
   • Halogens: −1 for F always, −1 for other halogens except when combined with oxygen or other halogens (positive oxidation numbers in these cases, varying values)

4.) The sum of oxidation numbers for all atoms in a molecule or polyatomic ion equals the charge on the molecule or ion.

Question 9

Equivalence point

Answer 9

The equivalence point is the point in a titration where the amount of titrant added is enough to completely neutralize the analyte solution.

Question 10

Titrant

Answer 10

a substance (such as a reagent solution of precisely known concentration) that is added in titration

Question 11

Analyte

Answer 11

a substance whose chemical constituents are being identified and measured.

Question 12

Chemical Indicators

Answer 12

any substance that gives a visible sign, usually by a colour change, of the presence or absence of a threshold concentration of a chemical species, such as an acid or an alkali in a solution. An example is the substance called methyl yellow, which imparts a yellow colour to an alkaline solution. If acid is slowly added, the solution remains yellow until all the alkali has been neutralized, whereupon the colour suddenly changes to red.

Question 13

End point

Answer 13

the volume of titrant actually measured