   # What volume of 0.200 M HCl must be added to 500.0 mL of 0.250 M NH 3 to have a buffer with a pH of 9.00? ### Chemistry & Chemical Reactivity

9th Edition
John C. Kotz + 3 others
Publisher: Cengage Learning
ISBN: 9781133949640

#### Solutions

Chapter
Section ### Chemistry & Chemical Reactivity

9th Edition
John C. Kotz + 3 others
Publisher: Cengage Learning
ISBN: 9781133949640
Chapter 17, Problem 90GQ
Textbook Problem
273 views

## What volume of 0.200 M HCl must be added to 500.0 mL of 0.250 M NH3 to have a buffer with a pH of 9.00?

Interpretation Introduction

Interpretation:

The volume of 0.200 M HCl added to 500 mL of  0.250 M NH3 has to be calculated when pH of the buffer solution is 9.0.

Concept introduction:

For weak base-strong acid titration the pH value can be calculated at various points before and after equivalence point.

The equilibrium established during the titration of NH3 with HCl. The equilibrium can be represented as,

NH3(aq)+ H3O+(aq)H2O(l)+NH4+(aq)

### Explanation of Solution

The calculation of volume is done by using Henderson Hasselbalch equation,

Given:

Refer to table 16.2 in the textbook for the value of Kb.

The value of Kb for ammonia is 1.8×105.

The pKb value is calculated as follows;

pKb=log(Kb)

Substitute, 1.8×105 for Kb.

pKb=log(1.8×105)=4.74

Therefore, pKb value is 4.74.

The initial concentration of NH3 is 0.250molL1.

The initial concentration of HCl is 0.200molL1.

The volume of NH3 solution is 500 mL.

Let the volume of HCl is x mL used to get the pH of buffer equals to 9.0.

The pOH value of buffer solution is 5.0.

Therefore total volume of the buffer solution is (500 + x )mL or (0.500 + 0.00x )L.

The calculation of moles is done by using the expression,

Numberof moles=concentration(molL1)volume(L)

The ICE table (1) for the reaction between NH3 and HCl is given below,

EquationNH3(aq)+H3O+(aq)H2O(l)+NH4+(aq)Initial(mol)0.1250.00200x0Change(mol)0.00200x0.00200x+0.00200xAfterreaction(mol)(0.1250.00200x)00.00200x

From ICE table (1),

Number of moles of ammonia left after reaction are (0.1250.00200x). The value of 0.00200x is very small as comparison to 0.125 therefore it can be neglected with respect to 0.125. So numbers of moles of ammonia left after reaction are 0.125 mol.

Number of moles of H3O+ left after reaction are 0mol

### 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

Find more solutions based on key concepts
The smallest unit of any substance is the _____. a. atom b. molecule c. cell

Biology: The Unity and Diversity of Life (MindTap Course List)

The eating pattern that best provides nutrients- singles out a rich source for each nutrient and focuses on the...

Nutrition: Concepts and Controversies - Standalone book (MindTap Course List)

Why is there a mass-luminosity relation?

Horizons: Exploring the Universe (MindTap Course List)

Identify a genetic condition that is not found by maternal or newborn screening.

Nutrition Through the Life Cycle (MindTap Course List)

What are the most powerful sources of anthropogenic sound in the ocean?

Oceanography: An Invitation To Marine Science, Loose-leaf Versin

When an object is displaced by an amount x from stable equilibrium, a restoring force acts on it, tending to re...

Physics for Scientists and Engineers, Technology Update (No access codes included)

Draw a structural diagram of 1-bromo-3-methylcyclohexane.

Introductory Chemistry: An Active Learning Approach 