Lab acid titrate

ACid-BAse TiTrATion reporT

USER NAME : TBC 3013

*********
PASSWORD :

ENTER
ENTER

LECTURER : DR ROSMILA MISNAN

GROUP MEMBERS

NAME MATRIC NO.

UMI ABIBAH BT SULAIMAN D20091034811

SITI RAHAYU BT MOHAMED NOOR D20091034855

D20091034872
NUR AFIQAH BINTI MUHAMAD APANDI

D20091034814
AMEERA BT YAHYA

ABSTRACT
 The main objective of this study was to investigate the
property of weak acid with pH changes.
 Result was collected from the pH meter during the
titration of acetic acid and phosphoric acid with 1mL of
0.1M NaOH .
 The graph pH against volume of NaOH is plotted and the
pKa value was determined. Both acid have different pKa
value and horizontal part of the curve.
 The study recommends that the larger the value of pKa, the
smaller the extent of dissociation while the smaller the pKa
value the higher the extent of dissociation.

INTRODUCTION

Titration  laboratory method of quantitative
analysis used to determine unknown
concentration of known
substance.
Pka value can determined pKa of an
acid from the graph.
value used to describe the
tendency of compounds or ions
to dissociate.
 This allows the proportion of neutral and charged species
at any pH to be calculated, as well as the basic or acidic
properties of the compound to be defined.

METHOD:

ACID
BASE TITRATION

METHOD : ACID BASE TITRATION

Titration apparatus Calibrated pH meter

Table : Volume of NaOH used and the pH values recorded

Graf 1: pH vs Volume of NaoH
(Acetic Acid)

pKa1=5.52

 To calculate the acid dissociation constant (pKa), one must
find the volume at the half-equivalence point, that is where
half the amount of titrant has been added to form the next
compound.

 From the graph plotted the pKa for acetic acid is 5.52
compare to the theoretical value which is 4.76.

 Halfway between each equivalence point, at 4 mL ,the pH
observed was about 5.52 , giving the pKa.

Graf 2: pH vs Volume of NaoH
(Phosphoric Acid)
pKa3=12.24

pKa2=7.44

pKa1=3.21

Then, the pKa value for phosphorus acid
accoding to the graph are 3.21,7.44 and
12.24 compare to the theoretical value
which are 2.15,7.20 and 12.35.

 Halfway between each equivalence point,
at 4 mL , 12.5 mL and 19.5, the pH
observed was about 3.21, 7.44 and
12.24 , giving the pKa.

The pKa from the experiment result was not
too accurate compare to the theoretical value.
This might be happened because of:

Not precisely added pH meter used also
1ml of 0.1M NaOH not too suitable and
for every step not measured the
titration process. accurate pH reading.

The pKa of an acid can be determined from the
part of the graph having flat or more horizontal
part of the curve.

The larger the value of pKa, the smaller the extent
of dissociation while the smaller the pKa value
the higher the extent of dissociation.

For acetic acid one horizontal part on the
curve
For phosphoric acid three horizontal parts

The difference arise

Due to acids having one or more than one
dissociation constant in order for all the H+ ions
can react completely with the OH- ions being
added during the titration process.

CONCLUSION

As a conclusion,
able to identidy the pKa of an acid by
using titration.
 learn how to use pH meter correctly.

REFERENCES
 https://docs.google.com/viewer?
a=v&q=cache:hWqGYixWkLsJ:www2.chem.ubc.ca/courseware/330/pKa.pd
f+&hl=en&gl=my&pid=bl&srcid=ADGEESi0c85vsFbBU4uwyfTNi2oMOBB8
prpi05jtfiPOheSrjLORUpXTvhvoLAAALjoQweS1utzrEGWeJkbUGBuwsix
CBSHf3ULXuzjHyDGhG4MAQNjL86hdoGlCTWzD0Hc6v12ZMAI0&sig=
AHIEtbTBuPkVBPk4IcMmhHj7n0u1hNGnXw
 https://docs.google.com/viewer?
a=v&q=cache:oOMX3c6_bfoJ:www.deltacollege.edu/emp/ckim/Labs_PDF/
AcidBaseTitrationCurveLab.pdf+&hl=en&gl=my&pid=bl&srcid=ADGEESjl3
hlEXLOO2UI_DXZGy35s8xAPURLrBVvoCgc7WH8O1lWP4yTZuSvdNh
oEgwdMKoVoXJsSIFhktON_PWOttJPKukddWLfQGe7UChJESb0bPka_sP
mk81gIvaAQE8o7lrIa1CAl&sig=AHIEtbRprjL5NExSdDjM_UtF5F-LJ4hdvQ

Lab acid titrate

More Related Content

What's hot

Viewers also liked

Similar to Lab acid titrate

More from Umi Biee

Lab acid titrate