Gen 6 - Acids and Bases Flashcards
What is a Bronsted Acid ?
An acid is a proton (ie. H+) donor
HA + H2O ⇔ ? + ?
H3O+ + A-
What is the equation for the equilibrium constant Ka ?
Name the two catergories of Acids in general chemistry ?
- Binary Acids
- Oxy Acids
Describe binary acids ?
Acids composed of hydrogen and a non-metal e.g. HCl
Describe the trend displayed by halogen containing binary acids ?
As halogen size increases, acid strength also increases.
Bond length also increases, which means bond strength decreases, leading to increased acidity.
What are Oxyacids ?
Anions containing a non-metal oxygen such as hydroxide or nitrate ions. They contain:
H - O - X
Describe the acidity of Oxyacids ?
The more oxygen atoms bound to the central atom, the more acidic the oxyacid.
What are diprotic acids ?
Acids with two protons e.g. H2SO4.
Describe the equilibrium constant Ka for diprotic or polyprotic acids ?
The acids would have Ka values for each of its protons, e.g. Ka1 for the first, Ka2 for the second.
The acids ionise in successive steps with their own Ka’s.
Ka1 is typically > Ka2
Give 8 examples of strong acids
- Perchloric HClO4
- Chloric HClO3
- Nitric HNO3
- Hydrochloric HCl
- Sulfuric H2SO4
- Hydrobromic HBr
- Hydroiodic HI
- Hydronium ion H3O+
What is a base ?
A proton accepter
B + H2O ⇔ ? + ?
HB+ + OH-
What is the equilibrium constant for a base ?
Give examples of strong and weak acids ?
Strong bases include any hydroxide of the Group 1A metals e.g. Na, K, Li etc…
The most common weak bases are ammonia and any organic amine.
Why is water amphoteric ?
It can act as an acid and a base
How does Ka relate to relative acid strength
The greater the magnitude of Ka, the stronger the acid (the more the reaction proceeds to the right).
What is a conjugate acid-base pair ?
The acid [HA] and the base produced when it ionises [A-].
E.g. HCN and CN-