acid base titration curves and acid_base indicators

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Jordan University of Science and Technology
Faculty of Engineering
Civil Engineering Department
CE 453
“Environmental lab”
“Acid-Base Titration Curves and Acid-Base
Indicators”
Experiment (3)
Student Name: Anas Mohammad Maghayreh.
Student ID: 20120023117.
Section #:1
Submission Date: 15/7/2015.
Submitted to: Dr. Hani Abu Qdais

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Abstract:*
Titration is an analytical method used to determine the exact amount of a
substance by reacting that substance with a known amount of another
substance. The completed reaction of a titration is usually indicated by a
color change or an electrical measurement. An acid/base neutralization
reaction will yield salt and water. In an acid-base titration, the neutralization
reaction between the acid and base can be measured with either a color
indicator or a pH meter. Acid + Base  Salt + Water
:Introduction*
The study of acid-base titrations involves consideration of the reactions,
which occur between acids and bases. For this purpose, it is convenient to
distinguish between strong and weak acids and bases.
The term strong usually refers to a substance, which is completely
dissociated into its ions in solution while weak, generally refer to substance,
which is partially dissociated .of course, various degree of strong and weak
exist.
The reaction of strong base and strong acid involves the combination of H+
and OH-
to form H2O and it is governed by the Ion product of water. The
titration of weak acid with a strong base involves at least two sequential
reactions, the initial reaction is the titration of the hydrated proton with OH
added .the second reaction, which may very rapid or slow, involves transfer
of the proton from the weak acid to H2O .in some cases, additional reactions
may be involved, the pH of the equivalence point.
Acid-base indicators which are usually an organic acids that contain an
ionizable proton H+
, these indicators change in color under specific H+
activity. To know the equivalence point an indicator that change color at that
point can be used.
In this experiment, a phenolphthalein color indicator will be used and methyl
orange. Phenolphthalein is colorless in acidic solutions and pink in basic
solutions.

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:Objective*
1. To determine the inter action of acids and bases and to examine methods for
determining equivalence points of reactions.
2. determining equivalence points in acids-bases titration using a PH meter or acid
- base indicators
:Apparatus*
1- PH meter.
2- Calomel reference electrode.
3- Bursts.
4- Magnetic stirrer
Picture (1): PH meter.
Picture (2): Magnetic stirrerPicture (3): flask with buret

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*Sample:
*Procedure:
1- Develop the titration curves to determine the equivalence points for
titration of :
a- 50 ml of 0.1M H2SO4 & 0.1M of NaOH .
b- 50 ml of 0.1M acetic acid & 0.1M NaOH .
2- Add 3 drops of an appropriate indicator to the 50ml of 0.1M H2SO4 and
insert the PH electrode and observe the PH values. Then titrate the
solution with 0.1M NaOH until the indicator change in color.
3- Repeat part 2 for another appropriate indicator.
4- Repeat part 2 and 3 for titration of 0.1M acetic acid with 0.1M NaOH
using an appropriate indicators.
:Results and Calculations*
Table1.1: volume of Phenolphthalein & methyl orange with change if PH
H2SO4 with Phenolphthalein H2SO4 with methyl orange
NaOH PH NaOH PH
0.0 2.42 0 2.4
0.5 2.42 0.5 2.44
1.0 2.42 1 2.5
1.5 2.45 1.5 2.56
2.0 2.55 2 2.65
2.5 2.70 2.5 2.87
3.0 3.10 3 3.2
3.5 4.70 3.5 6.5
4.0 10.5 - -

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*Discussion:
in this experiment we know that any volume of strong acid need the same volume
of strong base to get the equilibrium point where at which the pH must be 7 where
the moles of each of them are becomes equal and so the concentration of H+ and
OH- but that wasn't in our experiment .
The acid base titration is very important especially for environmental engineering
when treating the waste water and the need to clear it to become more useful.
our readings of PH was almost accurate but
There were some errors in this experiment and the data is not accurate
because of the following reasons:-
 Some personal errors like reading errors caused by the eye or the
non-horizontal taken reading.
 Some Factorial errors in the PH measure.
 The dishes were not clean from the first
 The taken reading was not taken at the accurate time .
*Conclusion:
when we added methyl orange to H2SO4 the color was converted from
orange to yellow and when we added phenolphthalein to H2SO4 the solution
was converted from colorless to the pink color
From this experimental it can concluded that any volume of strong acid need
the same volume of strong base to get the equilibrium point which the pH
must be 7 where the moles of each of them are becomes equal and so the
concentration of H+ and OH- but that wasn't in our experiment .
CH3COOH
volume(ml)
PH CH3COOH
volume(ml)
PH
0 3.3 0 3.3
0.5 3.55 0.5 3.6
1 3.8 1 4
1.5 4.3 1.5 4.2
- - 2 4.45
- - 2.5 4.7
- - 3 5
- - 3.5 5.4
- - 4 6
- - 4.5 10
Table1.2: volume of Phenolphthalein and PH

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Once again this process is very important specially for civil engineering
when treating with waste water and the need to clear it to become more
useful so it is very important to know everything of the kinetic of the reaction
of components with water and how to change the PH to make the reaction
going on and what is should do.
*References:
Lab manual
lab notes
Wikipedia (chemistry)
*Appendix:
0
2
4
6
8
10
12
0 2 4 6
H2SO4 with Phenolphthalein
Series1
0
1
2
3
4
5
6
7
0 1 2 3 4
H2SO4 with methyl Orange
Series1
0
1
2
3
4
5
0 0.5 1 1.5 2
CH3COOH with methly
orange
Series1
0
2
4
6
8
10
12
0 2 4 6
CH3COOH with
Phenolphthalein
Series1