Introduction to AcidBase Titration

1
Introduction to Acid-Base Titration

• Chapter 1

2
Introduction

• Water dissociate ( self- ionizes) into H
  (hydrogen ions) and OH- (hydroxide ions)
  naturally in a small content.

H2O gt H OH-
3
What is pH?

• pH is a measure of concentration of H define
  as
• pH -log H

Whether Water has pH 7, Acid pH lt 7 and base pH
gt7
4
Acid

• Able to ionize to produce hydrogen ion.
• HA gt A- H
• H2A gt A2- 2 H
• Eg. HCl gt Cl- H
• Eg.H2SO4 gt SO42- 2 H

5
Base

• Able to ionize to attract hydrogen ion.
• B H2O gt OH- BH
• Eg. NH3 H2O gt OH- NH4

6
Acid Base reaction

• Acid base gt water salt
• Eg. HCl NaOH gt water NaCl
• Eg. .H2SO4 2NaOH gt water Na2SO4

7
Acid Base titration

• Acid, base reaction with known concentration,
  volume.
• Titration method
• Indicator
• End point
• Titration curve.

8
Acid, base reaction with known concentration,
volume

• Measurement (weigh )
• Molarity (standardize)
• pH value
• Stoichiometric ratio ( ratio of hydrogen and
  hydroxide ions)
• Molarity acid x volume of acid
• Molarity base x volume of base

9
Titration method

• Unknown amount of Base add to acid for titration.
• Using buret flask titration until the end
  point.
• Report the volume used.

10
Indicator

• Phenolphthalein
• Methyl Red
• Methyl orange
• Few drops to be used
• To see the colour change of the solutions to
  show the end point .

11
End point

• pH 7.0
• Macid x Vacid Mbase x Vbase
• Color change sharply

12
Practice

• Computing practice
• Software Chemlab v2.0g

13
Titration curve

• Normally is something like this

14
How to use it?
1.choose procedure
2. Add chemical acid
15
Then??
3.Choose Acid
4. Use indicator for the acid
16
Data??
5.Use the pH meter for the acid
6. Click to collect the titration data
17
Start to titrate?
7.First add 50ml of base into buret for
titraton
8.right click the buret, choose titration
dialog box.
18
Titration dialog Box
9.You should click Start Vol to indicate the
intial volume. 10.click close just before
you estimate if it reach the end point.
19
Finished??
12.View the data
11.When the color of the acid changed, click
close and end vol to check the final vloume.
20
Results
This is a typical results of acid base titration.
21
Thank You !