Chapter 4 - Acids and Redox

Question 1

What is a strong acid?

Answer 1

An acid that releases all of its hydrogen atoms as H+ ions and completely dissociates in aqueous solutions
e.g. HCl

Question 2

What is a weak acid?

Answer 2

An acid that only releases some of its hydrogen atoms into H+ ions and only partially dissociates in aqueous solution
e.g. carboxylic acids

Question 3

What is the difference between acids and alkalis?

Answer 3

Acids release H+ ions in aqueous solutions
Alkalis release OH- ions in aqueous solutions

Question 4

What is a base?

Answer 4

A base neutralizes and acid to form a salt and water.

Question 5

What is an alkali?

Answer 5

A base which dissolves in water and releases OH- ions

Question 6

What is the neutralization reaction to form H2O?

Answer 6

H+ + OH- —> H2O

Question 7

What are the products of a metal and acid?

Answer 7

Salt and hydrogen
MASH

Question 8

What are the products of an alkali and acid?

Answer 8

Water and salt
AAWS

Question 9

What are the products of a base and acid?

Answer 9

Water and salt
BAWS

Question 10

What are the products of a carbonate and acid?

Answer 10

Water, salt and carbon dioxide
CAWS + COD

Question 11

What is the oxidation number of an element?

Answer 11

Always 0

Question 12

What is the total oxidation number of a compound?

Answer 12

The total charge of the atom
e.g. NH4+ has an total oxidation number of +1

Question 13

What is the oxidation number of O in a compound?

Answer 13

-2
e.g. H2O, Cao

Question 14

What is the oxidation number of H in a compound?

Answer 14

+1
e.g. NH3, H2S

Question 15

What is the oxidation number of F in a compound?

Answer 15

-1
e.g. HF

Question 16

What is the oxidation number of Na+ in a compound?

Answer 16

+1
e.g. NaCl

Question 17

What is the oxidation number of K+ in a compound?

Answer 17

+1
e.g. K2O

Question 18

What is the oxidation number of Mg2+ in a compound?

Answer 18

+2
e.g. MgCl2

Question 19

What is the oxidation number of Ca2+ in a compound?

Answer 19

+2
e.g. CaO

Question 20

What is the oxidation number of Cl- in a compound?

Answer 20

-1
e.g. HCl

Question 21

What is the oxidation number of Br- in a compound?

Answer 21

-1
e.g. KBr

Question 22

What is the oxidation number of I- in a compound?

Answer 22

-1
e.g. CaI2

Question 23

What is the oxidation number of H in a metal hydride?

Answer 23

-1
e.g. NaH, CaH2

Question 24

What is the oxidation number of O in peroxides?

Answer 24

-1
e.g. H2O2

Question 25

What is the oxidation number of O bonded to F ?

Answer 25

+2 e.g. F2O

Question 26

What does a roman numeral next to an element represent? e.g. Iron (II)

Answer 26

The oxidation number e.g. +2 for Iron (II)

Question 27

What is oxidation?

Answer 27

Addition of oxygen (not always) Loss of electrons Increase in oxidation number

Question 28

What is reduction?

Answer 28

Removal of oxygen (not always) Gain of electrons Decrease in oxidation number

Question 29

What are titrations used for?

Answer 29

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

Question 30

Why is checking the purity of a compound important?

Answer 30

In manufacturing Quality control Essential for pharmaceuticals to have a high level of purity Impurities in a drug may deal great harm to the consumer

Question 31

What apparatus is used to prepare a standard solution ?

Answer 31

Volumetric flask Can be 100cm^3 or 250cm^3

Question 32

What apparatus is needed to perform a titration?

Answer 32

Pipette - measuring out substance into a conical flask Burette - 50cm^3 to titrate a substance into the conical flask

Question 33

How is a mean titre calculated?

Answer 33

Repeating titres until two agree within 0.10cm^3 of each other, all others are considered inaccurate If all titres are included then the accuracy is lost