Chapter 4 - Acids and Redox

Question 1

What happens when an acid is dissolved in water?

Answer 1

When dissolved in water, it will release hydrogen ions as protons into the solution.

Question 2

What is a strong acid?

Answer 2

Releases all of its hydrogen atoms into solution.

It completely dissociates in an aqueous solution

Question 3

What is a weak acid?

Answer 3

Releases a small proportion of its available hydrogen atoms into the solution.
It partially dissociates in an aqueous solution.

Question 4

What is a base?

Answer 4

A base neutralises an acid to form a salt.

Question 5

What is an alkali?

Answer 5

A base that dissolves in water releasing hydroxide ions into the solution.

Question 6

What is the word equation for the neutralisation of acids with metal oxides/hydroxides?

Answer 6

Metal oxide/hydroxide + acid -> salt + water

Question 7

What is the word equation for the neutralisation of acids with alkalis?

Answer 7

Acid + alkali -> salt + water

Question 8

What is the word equation for the neutralisation of acids with carbonates?

Answer 8

Carbonate + acid -> salt + water + carbon dioxide

Question 9

What are the common acids?

Answer 9

HCl, H2SO4, HNO3, CH3COOH (ethanoic)

Question 10

Metal oxides, metal hydroxides, metal carbonates, and ammonia are all classified as?

Answer 10

Bases

Question 11

Common bases

Answer 11

Metal oxides: MgO, CaO, CuO
Metal carbonates: Na2CO3, CaCO3, CuCO3
Alkalis: NaOH, KOH, NH3

Question 12

What is a titration?

Answer 12

A technique used to accurately measure the volume of one solution that reacts exactly with another solution.

Question 13

What are titrations used for?

Answer 13

Finding the concentration of a solution.
Identification of unknown chemicals.
Finding the purity of a substance.

Question 14

What are concordant results?

Answer 14

Within 0.10 cm^3 of each other.

Question 15

When can a mean titre be worked out?

Answer 15

When two or more concordant results are obtained.

Question 16

When working out the mean titre, it is important to use only your accurate titres. Why?

Answer 16

• By repeating titres untill two agree within 0.10 cm^3, you can reject inaccurate titres
• Including all titres in the mean loses accuracy of the titration technique

Question 17

When is the oxidation number zero?

Answer 17

For elements on their own or bonded to atoms of the same element.

Question 18

What is the common oxidation number of oxygen?

Answer 18

-2

Question 19

What is the common oxidation number of hydrogen?

Answer 19

+1

Question 20

What is the common oxidation number of fluorine?

Answer 20

-1

Question 21

What is the common oxidation number of Na+ or K+?

Answer 21

+1

Question 22

What is the common oxidation number of Mg2+ or Ca2+?

Answer 22

+2

Question 23

What is the common oxidation number of other halides?

Answer 23

-1

Question 24

In what special case, can hydrogen have an oxidation number of -1?

Answer 24

When in metal hydrides.

i.e. NaH or CaH(2)

Question 25

In what special case, can oxygen have an oxidation number of -1?

Answer 25

In peroxides.

i.e. H(2)O(2)

Question 26

In what special case, can oxygen have an oxidation number of +2?

Answer 26

When bonded to fluorine.

i.e. F(2)O

Question 27

In ions, what is a trick for determining oxidation numbers?

Answer 27

The sum of the oxidation numbers, is equal to the total charge.

Question 28

What do roman numerals mean in the use of iron(II) or iron(III)?

Answer 28

Iron(II) represents Fe2+ with oxidation number +2.

Iron(III) represents Fe3+ with oxidation number +3.

Question 29

What is oxidation?

Answer 29

The loss of electrons.

Question 30

What is reduction?

Answer 30

The gain of electrons.

Question 31

What is oxidation in terms of oxidation number?

Answer 31

An increase in oxidation number.

Question 32

What is reduction in terms of oxidation number?

Answer 32

A decrease in oxidation number.