# Buffer Capacity

+

BCH 312 Experiment (7)

Buffer Capacity

+

Objectives

n

To understand the concept of buffer capacity.

n

To determine the maximum buffer capacity of a number of buffer solutions.

n

To establish the relationship between buffer capacity and buffer concentration.

+

n

Introduction

Common buffer mixtures contain two substances, a conjugate acid and a conjugate base .

n

Together the two species (conjugate acid and conjugate base) resist large changes in pH by absorbing the H+ ions or OH- ions added to the system. n

When H+ ions are added to the system they will react with the conjugate base in the buffer .

n

When OH- ions are added they will react with the conjugate acid in the buffer

! Thus the buffer is effective as long as it does not run out of one of its components.

+

Buffer Capacity

n

Quantitative measure of this resistance to pH changes is called buffer capacity.

n

Buffer capacity can be defined as the number of moles of H+/OH- ions that must be added to one liter of the buffer in order to decrease /increase the pH by one unit respectively.

n

Where [H+] = the hydrogen ion concentration of the buffer ,β is the buffer capacity , [C] is buffer concentration .

n

From the equation that the buffer capacity is directly proportional to the buffer concentration.

+

Method n

You are provided with 2 acetate buffers, pH=5. Each with different concentrations ; 0.1 M and 0.2 M . n  n

n

Transfer 8 ml of each buffer into a 50 ml beaker. Add 0.5 ml of ( 0.1 M) HCl from the burette and determine the pH of the solution after each addition Continue adding acid in until pH falls to about 2 pH units from your starting pH .

n

Plot a Curve of pH versus ml of HCl added and calculate the Buffer capacity

n

Then compare between two buffer which one has higher buffer capacity and why?

## Buffer Capacity

+ BCH 312 Experiment (7) Buffer Capacity + Objectives n  To understand the concept of buffer capacity. n  To determine the maximum buffer c...

#### Recommend Documents

Buffer Capacity
In this equation, H = 10-pH, Ka and Kw are the acid equilibrium constant and autoprotolysis of water, respectively, and

BUFFERS AND BUFFER CAPACITY
BUFFERS AND BUFFER CAPACITY. By Dr. Jan PlÃ¡tenÃ­k. Principle of buffering. A buffer solution is a solution that resists

Preparing Buffers and Buffer Capacity - Westminster College
Buffer Capacity = (number of moles of. -. OH or H3O. + added). (pH change)(volume of buffer in L). In this experiment, t

Buffer Preparation and Capacity - Fairmont State College
is a mixture of a weak acid and its conjugate base. The buffering capacity of a solution is determined using the Henders

Moisture Buffer Capacity of Different Insulation Materials
The results of these rather different measurement principles are discussed, and different ways are presented to determin

Buffer Capacity - Macatawa Area Coordinating Council
Dec 22, 2014 - 2. Determining Buffer Capacity. â Soils with higher clay and organic content in their composition have

Determination of pH and Buffer Capacity
a source for the buffers in one of their experiments. However they do not know which source will best resist a change in

Buffer Capacity, Ecosystem Feedbacks, and Seawater - MDPI
Sep 6, 2013 - As buffer capacity decreases, diel variation in seawater chemistry increases. However, a variety of ecosys

Evaluation of rapid buffer methods to estimate pH buffer capacity of
Abstract. Information on the pH buffer capacity (pHBC) of a soil is important in the management of soil acidification an

Mobile Phase Buffers, Part II â Buffer Selection and Capacity
Aug 22, 2014 - buffering capacity to maintain the target. pH. Buffer capacity or buffer index8 is a quantitative measure