Chapter 4 Acids and redox

Question 1

Acid

Answer 1

A species that releases H+ ions in aqueous solution.

Question 2

Strong acid

Answer 2

An acid that dissociates completely in solution.

Question 3

Weak acid

Answer 3

An acid that dissociates only partially in solution.

Question 4

Base

Answer 4

A compound that neutralises an acid to form a salt

Question 5

Neutralisation

Answer 5

A chemical reaction in which an acid and a base react together to produce a salt.

Question 6

Salt

Answer 6

The product of a reaction in which the H− ions from the acid are replaced by metal or ammonium ions.

Question 7

Alkali

Answer 7

A type of base that dissolves in water forming hydroxide ions, OH–(aq) ions.

Question 8

Common acids

Answer 8

Hydrochloric acid (HCl), Sulphuric acid (H2SO4), Nitric acid(HNO3), Ethanoic acid (CH3COOH)

Question 9

Common bases

Answer 9

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

Question 10

Neutralisation of an acid by a metal oxide/hydroxide

Answer 10

acid + metal oxide/hydroxide -> salt + water

acid + alkali -> salt + water

Question 11

Neutralisation of an acid by a metal carbonate

Answer 11

acid + metal carbonate -> salt + water + carbon dioxide

Question 12

Titration

Answer 12

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

Question 13

Titrations can be used for

Answer 13

• finding the concentration of a solution
• identification of unknown chemicals
• finding the purity of a substance

Question 14

Standard solution

Answer 14

A solution of known concentration

Made with a volumetric flask

Question 15

End point

Answer 15

The point in a titration where the indicator changes colour; the end point indicates when the reaction is just complete.

Question 16

Titre

Answer 16

The volume added from the burette when the volume of one solution has exactly reacted with the other solution.

Question 17

Concordant

Answer 17

Values agreeing within 0.10cm^3

Question 18

Oxidation number

Answer 18

A measure of the number of electrons that an atom uses to bond with atoms of another element. Oxidation numbers are derived form a set of rules.

Question 19

Rules for oxidation number

Answer 19

• always 0 for elements
• oxidation no. has a sign before the number
• O -2, H +1, F -1, Na K +1, Mg Ca +2, Cl Br I -1

H in metal hydrides -1
O in peroxides -1
O bonded to F +2
Sum of the oxidation numbers = total charge

Question 20

Oxidation

Answer 20

Loss of electrons or an increase in oxidation number.
addition of oxygen

Question 21

Reduction

Answer 21

Gain of electrons or a decrease in oxidation number.

Removal of oxygen

Question 22

completely dissociates

Answer 22

releases all hydrogen atoms into solution as H+ ions

Question 23

Partially dissociates

Answer 23

releases only a small proportion of hydrogen atoms into solution as H+ ions