Acid-Base Titrations
Concept Presentation by
Pooja Sharma
Rajni Kant Sharma
(13/07/12)
ACID AND BASES
Acids and bases are chemical compounds that
have distinctive properties in water solution. The
sour taste of a lemon, lime, or grapefruit, for
example, is caused by citric acid. The slippery
feel of ammonia, a common base, is characteristic
of all bases. Bases tend to taste bitter. Acids and
bases also change the color of certain dyes, such
as phenolphthalein and litmus. Acids change
litmus treated paper from blue to red. Acids
change basic phenolphthalein from red to
colorless. Bases change litmus treated paper from
red to blue and phenolphthalein from colorless to
pink.
DEFINITIONS OF ACID AND BASES
 Vante Arrhenius
- acids produce H+ ions in aqueous solutions
- bases produce OH- ions in aqueous solutions
 Johannes
Nicolaus Brønsted - Thomas Martin
Lowry
- acids are proton donors
-
bases are proton acceptors
 Gilbert
Newton Lewis
- acids are electron pair acceptors
- bases are electron pair donors
NEUTRALIZATION REACTIONS
Acids and bases are sometimes described as the chemical opposites
of each other .Acids and bases neutralize the action of each other.
This is why we take antacids for stomach-aches, because the
antacid is a base, and neutralizes the increased concentration of
an acid in the stomach.
If equivalent quantities of an acid and a base are combined, the two
compounds react to form a salt and water.
For example:
HCl(aq)
+ NaOH(aq) → NaCl(aq)
+ H2O(l)
hydrochloric
sodium
sodium
water
acid
hydroxide
chloride
This process is known as Neutralization Reaction.
TITRATION
 Titration
is a common laboratory technique used
to determine the concentration of substances in
solution. It’s a process in which one solution is
added to another solution such that it reacts
under
conditions
in
which
the
added volume may be accurately measured.
Titrations are most commonly associated
with acid-base reaction, but they may involve
other types of reactions as well.
ADVANCE PREPARATION FOR
ACID-BASE TITRATIONS
 Review
safety procedures.
 Collect all the materials required.
 The teacher should do the demonstration
himself/herself before doing it with the students.
 Remember to add Acid to Water not Water to
Acid.
TEACHING LEARNING
STRATEGIES
Any of the following strategies can be used
interactively with the class to build in student
accountability for learning:
 Brainstorm activity by whole class
 Mini-lecture method
 Model lab
 Lab activity by whole class
 Assignment on lab
 Teacher lab/ demonstrations, watching videos,
gizmos and use of other online resources.
VIDEO DEMONSTRATION ON ACID BASE
TITRATION

http://www.youtube.com/watch?v=TcAdpVzTSlg
CURRICULUM EXPECTATIONS
E2. Investigate qualitative and quantitative
properties of solutions, and solve related
problems.
 E2.7 Determine the concentration of an acid or a
base in a solution (e.g., the concentration of acetic
acid in vinegar), using the acid–base titration
technique [PR, AI]
 E3. Demonstrate an understanding of qualitative
and quantitative properties of solutions.

LESSON SEQUENCES
Lesson
1: Acid and Bases
Properties and their reactions
Lesson
2: Neutralization
Process of neutralization with reactions
Lesson
3: pH value
Definition, Role and Importance of pH
value
Lesson 4: Titration
Role of most common types of qualitative acid-base titrations
Lesson 5: Demonstration of acid –base titration
By using Gizmo’s and videos
Lesson 6: Lab activity by the students with record of data and
calculations
HCl(aq)
+ NaOH(aq) → NaCl(aq)
+ H2O(l)
hydrochloric
sodium
sodium
water
acid
hydroxide
chloride
STUDENTS’ LAB ACTIVITY


Equipment and Materials
Chemical safety goggles, lab apron, large test tube, Berol
pipette, test tube rack, burette clamp, retort stand, wash bottle,
burette, 100 ml beaker, 250 mL flask, two 250 ml beakers,
dropper, dilute hydrochloric acid (0.1mol/L), sodium
hydroxide solution (concentration unknown), Phenolphthalein
indicator,.
Safety Precautions
Before starting the titration lab, review safety precautions and
perform a quick review to check how well students are at
determining the concentration of a diluted solution from a
standard solution before they perform any calculations. The
solutions of sodium hydroxide and hydrochloric acid are both
irritants. Avoid skin contact. If some does spill on your skin,
wash the affected area with plenty of cool water. Report any
spills to your teacher.
 Procedure
•Prepare a data table. Record all of your experimental results in the
table as soon as you obtain them.
•Clean all glassware before you use it.
•Obtain about 120 ml of hydrochloric acid solution in a 250 ml
beaker.
•To clean the burette - make sure it is closed and, using a funnel,
pour about 10 ml of the hydrochloric acid solution into the burette.
Place the burette in a burette holder on a retort stand and place a
catch beaker under the spout of the burette and let the hydrochloric
acid run through. Repeat this procedure twice more using new 10
ml samples of hydrochloric acid each time.
•Refill the burette so that the meniscus of the hydrochloric acid
solution is at the 0 ml mark.
•Obtain 120 ml of sodium hydroxide in another (clean!) 250 ml
beaker.
•Pipette 25 ml of the sodium hydroxide into the flask.
•Place 3 drops of phenolphthalein into the flask that contains the
base. The solution turns pink.
•Place the flask under the burette.
•Slowly add hydrochloric acid from the burette, one ml at a
time. Stop after every 1 ml addition to swirl the solution in
order to make sure that the acid is properly mixed with the
base. Record the final reading when pick colour disappears.
•Repeat the titration (steps 7 – 10) twice more. Do not refill
the burette unless you have run out of acid. Record the
initial reading of the burette and add acid from that point.
Record all of your data
POTENTIAL STUDENT’S DIFFICULTIES
Acid-base titrations are common laboratory activities carried out in
high school chemistry courses. Using a series of qualitative and
computer-based tasks, this study examined sixteen American
students’ understanding of titrations. The findings indicated that
students having considerable difficulty with acid-base chemistry,
were unable to describe accurately acid-base concepts, such as pH,
neutralization, strength, and the theoretical description of acids and
bases. Further, most students could not relate the concepts to actual
solutions. Student difficulties stemmed from a lack of understanding
of some underlying chemistry, such as the nature of chemical change
and the particulate nature of matter. A number of factors were
identified as contributing to these difficulties, including the
overstuffed nature of introductory chemistry itself, the emphasis
during instruction on solving numerical problems, and the dominant
role played by the textbook. [Chem. Educ. Res. Pract., 2006, 7 (1),
32-45]
DIFFERENTIATED ASSESSMENT STRATEGIES
(SOLUTIONS TO STUDENT’S DIFFICULTIES)

Assessment & Evaluation

ELL student accommodations

Special needs student accommodations
PRACTICAL APPLICATIONS AND
SOCIETAL IMPLICATIONS





Softening of water using soda lime process by municipalities
and wastewater treatment.
Neutralization has many practical applications. Reclamation
(restoration) of land once used for mining also involves
neutralization reactions.
Neutralization is also used to deal with environmental
problems.
Acids and bases are used in the manufacture of fertilizers,
synthetic fabrics, pigments, petroleum, iron and steel,
explosives, dyes, plastics, pesticides, soaps and detergents,
paper, film, and many other chemicals.
They are also used for various other purposes, including
cleaning surfaces, refining oil and sugar, electroplating metals,
and treating food products.
•Sulphuric acid is the most widely used chemical in industry.
•Nitric acid, another important industrial acid, is used in the
manufacture of fertilizers, plastics, photographic film, and
dyes and explosives as dynamite and TNT.
•Hydrochloric acid is used to clean metals, brick and tile; it
is used in the manufacture of sugar and glue.
•pH plays an important role in biological reactions.
REFERENCES









http://www.scienceclarified.com/A-Al/Acids-and-Bases.html
http://www.okstate.edu/jgelder/acidPage25.html
http://specialed.about.com/od/teacherstrategies/a/differenti
ated.htm
http://preparatorychemistry.com/Bishop_Titration.htm
http://www.isbe.net/assessment/pdfs/ell_guidance.pdf
http://www.teachervision.fen.com/specialeducation/resource/5347.html
http://www.spectrumtrainingsystemsinc.com/files/PatrickS
chwarzListActivity2.pdf
http://chemistry.about.com/od/chemistryquickreview/a/titra
tioncalc.htm
http://www.youtube.com/watch?v=XnHH-pXqqRs
http://www.youtube.com/watch?v=TcAdpVzTSlg