Chemistry Buffer system

1. OBJECTIVE
S
❏ Acidity and Basicity.
❏ Definition and Reaction of Acidity and Basicity.
❏ Relationship between the Acidity and Basicity.
❏ Where we have acid and base in our bodies (general).
❏ Definition of the PH and Levels of it.
❏ How we can calculated the PH?
❏ How we can measure PH (indicators).
❏ How does the blood maintain PH?
❏ Definition of the Buffer system in the human body.
❏ The buffer capacity.
❏ Different types (levels) of the buffer.
❏ What happen if we have more acid or base in our bodies ?
❏ Bicarbonate buffer system

2. ACIDIT
YAcid

3. BASICITY
A basic solution has a low H+ concentration, less than that of pure
water. Solutions are classified as acidic or basic based on their
hydrogen ion concentration relative to pure water. Basic (alkaline)
solutions have a lower H+ concentration than acids

4. WHAT IS PH?
The concentration of hydrogen ions in a solution is usually denoted by the
term pH, which is the negative log10 of the hydrogen ion concentration
expressed in moles per liter (mol/L)
pH = -log[H+]
The pH value is an expression of the ratio of [H+ ] to [OH‐] (hydroxide ion
concentration). Hence, if the [H+ ] is greater than [OH‐ ], the solution is acidic.
Conversely, if the [OH‐ ] is greater than the [H+ ], the solution is basic.
Since pH is a logarithmic value, it doesn’t have any unit.

5. IMPORTANCE OF MAINTAINING
PH.
● Most living things depend on a proper pH level to sustain life
● The blood flowing through our veins must have a pH between 7.35 and
7.45. Exceeding this range by as little as one‐tenth of a pH unit could
prove fatal.
● To attain high crop yields, farmers must condition their fields to the
correct pH value
● Rain is typically around 5.6 pH but, in some areas, it increases to harmful
levels between 4.0 and 5.0 pH due to atmospheric pollutants resulting in
acid rain.

6. CALCULATE
PH
To calculate the pH of an aqueous solution you need to know the
concentration of the hydronium ion in moles per liter (molarity).
The pH is then calculated using the expression:
pH = - log [HзO ].
similarly, pOH is the negative of the logarithm of the OH- ion
concentration.
pOH = - log [OH-]
pH + pOH = 14

7. EXAMPLES:
Example1: Calculate the pH of 0.06 mol/L HCl.
pH = − log0.06 = 1.22
Example 2: Calculate the pH of 0.02 mol/L H2SO4 .
pH = − log0.04 = 1.3979 = ~ 1.4
What is the pOH of a solution that has a hydroxide ion concentration
of 4.82 x 10-5 M?
pOH = - log [4.82 x 10-5] = - ( - 4.32) = 4.32

9. BUFFER SYSTEM IN THE HUMAN BODY
Buffer systems play important roles in nature and in laboratory settings. In nature, they
offer protection to living organisms, while in labs they're used to create an
environment with a stable pH.
Buffer : A solution that resists change in pH when limited amounts of an acid or a base
are added to it; an aqueous solution containing a weak acid and its conjugate base

10. BUFFER CAPACITY
◄
◄

11. WHAT HAPPEN IF WE HAVE MORE ACID IN OUR
BODIES?
● When your body fluids contain too much acid, this is known as Acidosis.
● Acidosis occurs when your kidneys and lungs cannot keep your body’s pH in
balance.
● The pH of your blood should be around 7.4. - According to the “American
Association for Clinical Chemistry”
● A lower pH means that your blood is more acidic.
● Acidosis is characterized by a pH of 7.35 or lower.

12. WHAT HAPPEN IF WE HAVE MORE ACID IN OUR
BODIES?
● There are two types of acidosis: Respiratory and Metabolic acidosis.
○ Respiratory acidosis occurs when too much CO2 builds
up in the body. “Normally the lungs remove CO2 while
you breathe. However, sometimes your body can’t get
rid of enough CO2.
○ Metabolic acidosis starts in the kidneys instead of the
lungs. It occurs when they can’t eliminate enough acid or
when they get rid of too much base.