Acids and Bases
Many things are either Acids or Bases
• Now not all Acids and Bases are dangerous many are actually very
helpful or tasty.
• For example lemons have a slight sour taste because they contain acid
compounds
• We also use vinegar an acidic solution in a lot of our foods. Acids help
us to eat larger meals without feeling over full.
• We use to use many bases to make soap and now they are used in
tonic water.
Acids
• They have both physical and chemical properties that are unique.
• For example they have a sour taste this is a physical property.
Acids
• Chemically they are used to remove rust, and in refining metals or
stone such as Jade.
• In water Acids release positive H ions.
Acids
• For example in water Hydrogen Chloride breaks apart into
• 𝐻𝐶𝑙 𝑎𝑞 → 𝐻 + 𝑎𝑞 + 𝐶𝑙 − 𝑎𝑞
• Acids also have a PH that is less than 7
• PH stands for potential hydrogen
Bases
• Bases taste bitter and in compounds they have a slippery feel. This is
why teas and coffees are bitter.
Bases
• Bases are often used in medicines which is why they taste horrible.
• Many bases are highly corrosive and when they dissolve in water they
release negative OH ions.
• 𝑁𝑎𝑂𝐻 𝑎𝑞 → 𝑁𝑎+ 𝑎𝑞 + 𝑂𝐻 − (𝑎𝑞)
• Bases are also greater then 7 on the PH scale
To identify acids and bases we use indicators
the most common is called Litmus Paper.
• Red Litmus Paper turns Blue in a Basic solution
• Blue Litmus Paper turn Red in an Acidic solution
• This does no tell you how much Acid or Base there is that requires
using the PH Scale
The PH scale goes from 0 to 14
• The more acidic a solution is the lower the number is.
• For example a lemon is PH 2 and milk is PH 6 so lemons have a higher
concentration of 𝐻 + 𝑖𝑜𝑛𝑠
• The more basic a solution is the higher the number is.
• For example oven cleaner has a PH of 13 and eggs have a PH of 8.
• This means that the oven cleaner has a higher concentration of
𝑂𝐻 − 𝑖𝑜𝑛𝑠
Pure water has a PH of 7 it is neutral and
neither acidic or basic
• Each level of the PH scale is separated by a power of 10. so PH 6 is 10
times more acidic then PH 7.
• So the amount of positive H ions is 10 times greater.
A way to test PH is to use PH paper it is
usually yellow in colour.
Naming Acids:
• We will put acids into two categories:
• Binary Acids
• Oxoacids
Binary Acids are made or Hydrogen and a
Non-Metal an example of this is Hydrogen
Chloride gas when it is dissolved in water. The
acidic solution HCL(aq) is formed.
When the Hydrogen and Non-metal
compound is dissolved into water it needs a
new name.
The rules for naming molecular compounds
apply to acids.
However many acids also have a classical
name from before the new naming system
was set up.
1) the root of the non-metal is used in the
name.
2) the prefix Hydro is added to the root name
3) the ending –ic acid is added to the root
name.
Example HCl
• HCl is called Hydrogen monochloride
• However its classical Acid name is:
• Hydrochloric acid.
Oxoacids are made of Hydrogen, Oxygen and
another element. The most common example
is an acid that is made of Hydrogen and a
Polyatomic Ion that contains Oxygen.
You can name Oxoacids using the usually
methods or you can use their classical names
• 1) write the polyatomic ion without –ate or –ite ending
• 2) if ion name ended in –ate replace it with –ic at the end of the name
• 3) if it ended in –ite replace it with –ous at the end of the name.
• 4) add the word acid
Basic compound use the normal naming
system. Just remember all Bases have OH
negative ions in them.