C5 Acids, Salts, Bases And Alkalis

Question 1

What is an acid?

Answer 1

Substances that react with water to release H+ ions.
Ph less than 7
Proton donor
Examples of common acids:
H2SO4 - Sulfuric acid
HCl - Hydrochloric acid
HNO3 - Nitric acid 
H3PO4 - Phosphoric acid
CH3COOH - Ethanoic acid

Question 2

What are bases?

Answer 2

Substances that react with acids to form a salt and water (and sometimes carbon dioxide as well).
Bases are protons acceptors
Examples of common bases:
Metal oxides like CaO
Metal carbonates like Na2CO3

Question 3

What are salts?

Answer 3

Ionic substances formed when acids react with bases.
A compound formed when some or all hydrogen is replaced by a metal 
Examples of common salts:
Sulfates from sulfuric acid
Chlorides from hydrochloric acid
Nitrates from nitric acid 
Phosphates from phosphoric acid 
Ethanoates from ethanoic acid
Citrates from citric acid

You identify these as acids but the hydrogen is replaced by a metal ion (or a ammonium ion)

Question 4

What are alkalis?

Answer 4

A special type of base that reacts with water to release OH- ions.
Ph more than 7
Examples of common alkalis:
NH3 - ammonia
Examples of common alkalis plus hydroxides:
NaOH - sodium hydroxide 
KOH - potassium hydroxide 
Ca(OH)2 - calcium hydroxide

Question 5

What is the difference between strong and weak acids

Answer 5

Strong acids completely ionise in aqueous solutions

Weak acids acids do not ionise completely in aqueous solutions