Buffer Capacity and Buffer Equation.pptx

BUFFER EQUATION & BUFFER
CAPACITY IN GENERAL
NAME: AAQUIB PARVEZ RIYAZODDIN
COLLEGE: VIDYA NIKETAN COLLEGE OF PHARMACY ANJANGAON SURJI
By Aaquib parvez

• The amount of acid/base required to produce a unit change in
pH of a buffer solution is known as buffer Capacity.
• It is also known as
1.Buffer Index
2.Buffer value
3.Buffer Efficiency
4.Buffer coefficient
1.Buffer Capacity

• Buffer Equation
• Also known as Handerson Hasselbalch equation
• It is used to calculate the pH of a buffer solution.
β= ∆A or ∆B/∆pH
Where
β= Buffer Capacity
∆Aor∆B= Amount of acid/ base is required
∆pH=Change in pH
1.For Acidic buffer
2.For Basic buffer

[Weak acid and it’s salt ]
1.For Acidic Buffer :
• The pH of acidic buffer can be calculated From the
dissociation constant(Ka) of the weak acid and its salt.
• Let’s take a weak acid(HA) and it’s salt( BA).
HAH+
+ A-
BAB+
+A -
(Weak acid)
(It’s salt)
• By applying Law of mass action
Ka=[H+
] [A-
]/[HA]

Ka[HA]=[H+
][A-
]
Ka[HA]/[A-
]=[H+
]
[H+
]=Ka[HA]/[A-
]
Where,
HA=weak acid
A-
= salt
[H+
]=Ka [Acid]/[Salt]
Taking (-log) both side
-log[H+
]= -log(Ka[Acid]/[Salt])

Now,
pH=-log[H+
]
Pka=-logKa
-log[H+
]= -logKa-log[Acid]/[Salt]
Hence,
pH= Pka – log [Acid]/[Salt]
pH=Pka+ log[Salt]/[Acid] {For Acidic Buffer}

2. For Basic Buffer
pOH = Pkb+ [Salt]/[Base]

Buffer Capacity and Buffer Equation.pptx

Buffer Capacity and Buffer Equation.pptx

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Buffer Capacity and Buffer Equation.pptx