Chapter 4 - Acids and Redox

Question 1

What is an acid?

Answer 1

A substance that releases H+ ions (protons) when dissolved in water.
A proton donor.

Question 2

What happens when a strong acid reacts with water?

Answer 2

The strong acid releases all its hydrogen atoms into solution as H+ ions and completely dissociates in aqueous solutions.

Question 3

What happens when a weak acid reacts with water?

Answer 3

The weak acid only releases a small proportion of its available hydrogen atoms into solution as H+ ions. A weak acid partially dissociates in aqueous solution.

Question 4

What is a base?

Answer 4

A substance that neutralises an acid to form a salt and water.
A proton acceptor.

Question 5

What is an alkali?

Answer 5

A base that dissolves in water releasing hydroxide ions (OH-) into the solution.

Question 6

Acid + Metal oxide/hydroxide →

Answer 6

Acid + Metal oxide/hydroxide → Salt + Water

Question 7

What is neutralisation?

Answer 7

A reaction between an acid and a base to produce a salt.

Question 8

Acid + Metal carbonate →

Answer 8

Acid + Metal carbonate → Salt + Water + Carbon Dioxide

Question 9

What are titrations used for?

Answer 9

Finding the concentration of a solution

Question 10

What is a standard solution?

Answer 10

A solution of known concentration.

Question 11

What is the oxidation number of calcium in Ca2+

Answer 11

+2 (not 2+ like an ionic charge)

Question 12

Acid + Metal →

Answer 12

Acid + Metal → Salt + Hydrogen

Question 13

Redox reactions involve…

Answer 13

…reduction AND oxidation

Question 14

Reduction is…

Answer 14

…the gain of electrons

…a decrease in oxidation number

Question 15

Oxidation is…

Answer 15

…the loss of electrons

…an increase in oxidation number

Question 16

What should one ensure in a titration to prevent human error?

Answer 16

Ensure the bottom of the meniscus is viewed at eye level.

Question 17

What are the common exceptions of oxidation numbers?

Answer 17

In a metal hydride (e.g. NaH), hydrogen has an oxidation number of -1

When bonded to fluorine, oxygen has an oxidation number of +2

In a peroxide (e.g. H2O2), oxygen has an oxidation number of -1.

Question 18

What do roman numerals in names of compounds represent?

Answer 18

The oxidation number of an element.

Question 19

Acid + Ammonia →

Answer 19

Acid + Ammonia → Ammonium Salt

HX + NH3 → NH4X

Question 20

What is a disproportionation reaction?

Answer 20

A reaction where the same element is both oxidised and reduced.

Question 21

What is a titration?

Answer 21

A form of volumetric analysis in which a known volume and concentration of a solution is reacted with a measured volume of another solution.

Question 22

What is neutralisation?

Answer 22

A reaction between an acid and a base to produce a salt.

Question 23

What is an oxidising agent?

Answer 23

A substance which oxidises other things but are themselves reduced.

Vice versa for reducing agents.