   Chapter 15, Problem 87AE

Chapter
Section
Textbook Problem

# Phosphate buffers are important in regulating the pH of intracellular fluids at pH values generally between 7.1 and 7.2.a. What is the concentration ratio of H2PO4− to HPO42− in intracellular fluid at pH = 7.15? H 2 PO 4 − ( a q ) ⇌ HPO 4 2 − ( a q ) + H + ( a q ) K a = 6.2   ×   10 − 8 b. Why is a buffer composed of H3O4 and H2PO4− ineffective in buffering the pH of intracellular fluid? H 3 PO 4 ( a q ) ⇌ H 2 PO 4 − ( a q ) + H + ( a q ) K a = 7.5   ×   10 − 3

(a)

Interpretation Introduction

Interpretation:

Phosphate buffers have been stated to be important in regulating the pH of intercellular fluids at pH values generally between 7.1 and 7.2 . The given questions based on phosphate buffers are to answered.

Concept introduction:

A solution that resists a change in the pH on addition of an acid or an alkali is termed as a buffer solution.

Explanation

Explanation

To find the value of pKa

The value of pKa is calculated by the formula,

pKa=log(Ka)

Substitute the value of Ka in the above expression.

pKa=log(6.2×108)=7.21_

To find the concentration ratio of H2PO4 and HPO42 in intracellular fluid at

The relation between pH and pKa is given by Henderson-Hasselbach equation. According to this equation,

pH=pKa+log[Salt][Acid]

The calculated value of pKa is 7.21 .

Substitute the value of pKa and the given value of pH in the Henderson-Hasselbach equation.

7.5=7

(b)

Interpretation Introduction

Interpretation:

Phosphate buffers have been stated to be important in regulating the pH of intercellular fluids at pH values generally between 7.1 and 7.2 . The given questions based on phosphate buffers are to answered.

Concept introduction:

A solution that resists a change in the pH on addition of an acid or an alkali is termed as a buffer solution.

### Still sussing out bartleby?

Check out a sample textbook solution.

See a sample solution

#### The Solution to Your Study Problems

Bartleby provides explanations to thousands of textbook problems written by our experts, many with advanced degrees!

Get Started 