This document describes an experiment measuring the conductivity of a sodium hydroxide (NaOH) and water mixture over time using a continuous stirred tank reactor (CSTR). The CSTR apparatus and methodology are described in detail. Graphs of conductivity measurements over time are shown. The discussion explains that conductivity increases with ion concentration, so the NaOH solution conductivity increases over time as ions dissolve in water. Pure water does not conduct electricity well due to lacking ions, while ionic substances like salt water conduct better.

1. Continuous stirred tank reactor (CSTR):
Conductivity measurement
Name of student: Shwan Sarwan Sadiq
Group: B
Date of Exp. OCT 28th
2015
Submission date: NOV 11th
2015
Supervisor: ms.lameha
Chemical Engineering Department
Chemical reactors lab
3rd stage
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2. Table of content:
Aim of the experiment 3
Theory 4 &5
Apparatus
6,7,8,9,10,11,12,13,14,15,16
Methodology 17
Data sheet 18
Graphs 19
Discussion 20&21
References 22

3. Aim of the experiment:
Measurement of the conductivity for a base – water
mixture along time at room temperature using
different concentrations.

4. Theory:
CSTR:
_it’s called ‘mixed reactor ‘, ‘back mix reactor’, ‘Continuous stirred
Tank reactor CSTR ‘. It’s a reactor in which contents are
well mixed And uniform throughout. Thus, the exit stream
from the reactor has the same composition as the fluid
within the reactor. The pattern of flow is mixed flow and is
used primarily for liquid phase reactions.
More specifically, continuous stirred tanks are used for
relatively slow reactions of liquids and slurries. .
_Its normal operation is at steady state, where the conditions
in the
Reactor don't change with time and it’s assumed to be
perfectly mixed,
So the contents have relatively uniform properties such as
temperature, Density, etc.
Conductivity:
Conductivity is a measure of how well a solution conducts
electricity. To carry a current a solution must contain charged
particles, or ions. Most Conductivity measurements are made

5. Continue..
in aqueous solutions, and the ions responsible for the
conductivity come from electrolytes dissolved in the Water.
Salts (like sodium chloride and magnesium sulfate), acids (like
Hydrochloric acid and acetic acid), and bases (like sodium
hydroxide and Ammonia) are all electrolytes. Although water
itself is not an electrolyte, it does have a very small
conductivity, implying that at least some ions are Present.
The ions are hydrogen and hydroxide, and they originate
from the Dissociation of molecular water.
_In conductivity works, it is necessary to work with as pure
As possible solvents because any impurity affects to
Conductivity therefore, the distilled water has to be used
During the experiments rather than tap water.

6. Apparatus:
To study CSTR reactor, it is necessary to use a service
Module and Interface called QUSC. This unit provides the
reagents and the thermostatized water to the reactor under
study.
Base module and interface, QUSC:
QUSC. Service Unit:
_This unit is common for the Chemical Reactors, and can
work with one or several reactors.
_ Accommodation and exchange system of the reactors,
quick and easy to handle.
_It supplies all the services for the operation of each reactor
_ Anodized aluminum structure and panels of painted steel.
_ Main metallic elements in stainless steel.
_ Diagram in the front panel with similar distribution to the
elements in the real unit.

7. Continue..
_2 Peristaltic dosing pumps with variable speed. Flow rate
up to 3 l. /h.
(Unit standard disposition). With another disposition, they
could reach a flow rate up to 10 l./h.
_ Thermostatic bath of 6 l. capacity. Temperature control of
hot water in order to maintain the reactor temperature.
_Pump of 3 l. /min., to impel the thermostatization water
from the bath to the reactor.
_2 Tanks for the reagents, of 1 l. capacity each one, made in
Pyrex glass.
_The control of the reaction is carried out by a conductivity
sensor,
Which allows the reaction evolution parameterization in real
time.
_ Three “J” type temperature sensors, one to know the
thermostatic
bath temperature in a continuous way and two sensors
to know the

8. Continue..
Water temperature at the thermostatic bath water inlet and
outlet.
_ Quick connectors with shutoff valve that enable an easy
coupling of
The Service Unit to the chosen reactor.
_All elements of this unit are chemically resistant.

9. Continue..
Electronic Console:
Metallic box.
_ Temperature sensors connectors.
_ Digital display for temperature sensors.
_ Selector for temperature sensors.
_ Peristaltic pumps controllers and switches.
_ Water pump switch.
_ Stirrer switches.
_heating element controller.
The reagents supply circuit is constituted by a PTFE pipe of 6
mm. The reagents are introduced into two Pyrex vessels
of 1 liter each placed at the rear part. There are two

10. Continue..
Peristaltic pumps to move the reagents. The following valves
are located at the Module’s base:
_The 6 mm valves (1) are mounted at the peristaltic
pumps outlet and they must be connected to the reagent
inlet of the Reactor.
_The ball valves with the mark (2) are of water outlet and
inlet.

11. Continue..
They have a tube of 8 mm which must be connected to
the water inlet and outlet of the reactors. The
connections are Interchangeable between them.
_The temperature control system consists of a thermostatic
Bath, whose temperature is controlled by means of a PID
Control on this bath temperature. The thermostated water
System is also composed of a thermostatization water
impeller pump, with variable flow by means of the valves (2).
_The data acquisition and process control system is
Centralized in the electronic interface connected to the
different elements which constitute both the base
module and the reactor module.
Continuous Stirred Tank Reactor Module:
The body of the reactor, made in Pyrex glass, has a capacity
of 2 liters and it is specially designed to work in
continuous, although it also allows to work in discontinuous
if the reagents are introduced to the desired volume and

12. Continue..
the pump are stopped. There is a manual discharge valve at
the lower part for this purpose.
_During the operation in continuous, the final product outlet
is carried out by the stainless steel tube (4) which is
regulable in height, loosening the brass nut.
This allows to work with different reaction volumes.
_The stirring system (1) with speed control and indication
allows The study of the influence of both continuous and
discontinuous Agitation in the reaction kinetics.

13. Continue..
_ System to heat the reaction formed by a stainless steel coil
(3) through which the water from the Service Module bath
circulates. The water inlets to the coil from the service
module will be done through the fittings of 8 mm placed
at the lower part of the reactor.
_The monitoring of the reaction is carried out using a
conductivity cell with conductivity meter, which allows
measuring the evolution of the reaction in real time.
_The thermostatic bath has been designed to keep constant
the temperature around the reactor. A volume of 9 liters has
been taken, because this volume allows the control of the
temperature of water every 0.1ºC.

14. Continue..
The conductivity meter or conductivity sensor:
Applies a temperature compensation factor by default to
Compensate for the change of the measurement due to
Temperature. Such factor has a factory-set value of 2%,
which
implies a correction of 2% per degree increased with respect
to the reference temperature. Depending on the practical
exercise to be performed, we may want this value be 0%, so
that it does not compensate for the temperature influence
(when we want to study ionic conductivities) or have a
specific value between 0 and 5% (when we want to

15. Continue..
associate conductivity and conversion of the reaction directly).
The default factor is 2%, but it can be optimized by
studying the conductivity relation of each species with
the temperature and then adjusting the compensation
factor (between 0 and 5%) that better fits each reaction
1) To compensate for the compensation factor of the
Conductivity meter, press “TEMP”. The value adjusted
At that moment will appear in the screen. Press “TEMP”
Again to exit the screen.
2) To adjust the % of the compensation factor press“TEMP”
and then the key “FACTOR ADJ” successively until obtaining
the desired value (Between 0 and 5%). Press “TEMP” again
to exit.

16. Continue.. (CSTR)

17. Methodology:
1-dissolve 4 grams of NaOH in some distilled water .
2-fill a bottle of 800 ml of the NaOH mixture and
additional distilled water. And another bottle of water.
3-fix the bottles in their places and tide the pipes and the
valves.
4-power on the Electronic Console and read the first
reading of its conductivity.
5-open the pump and read the readings of the
conductivity for every 30 seconds.
6-after finishing readings for several times turn off the
pump and the Electronic Console then pour all the liquid
from the reactor.

18. Graphs:

19. Discussion:
We can measure the conductivity of an aqueous according
to the time with different concentration by using an reactor
with an mixer from recording the conductivity we get the
amount of how much the aqueous conducts.
Pure water is not a good conductor .Ordinary distilled
water in equilibrium with carbon dioxide of the air has a
conductivity of about 10 x 10-6
W-1
*m-1
(20 dS/m).
Because the electrical current is transported by the ions
in solution, the conductivity increases as the
concentration of ions increases.
Thus conductivity increases as water dissolved ionic
species.
Typical conductivity of waters:
Ultra pure water 5.5 · 10-6
S/m
Drinking water 0.005 – 0.05 S/m
Sea water 5 S/m
when certain substances are dissolved in water, the solution
does conduct electricity. You can make a simple device that
shows how well a solution conducts electricity. This device
uses a flashlight bulb to indicate how well the solution
conducts electricity. The better the solution conducts
electricity, the brighter the bulb will glow.

20. Continue..
Since distilled water is purified and does not contain
any impurities, it is unable to conduct electricity. Water
molecules on their own have no charge and as a result
they cannot swap electrons. Without the swapping of
electrons, electricity is unable to travel through distilled
water.
Salt water, on the other hand, is considered a good
conductor of electricity because it contains ions in it.
Tap water, although it doesn't taste salty, can also
conduct electricity because it isn't pure. The water from
the kitchen sink often has traces of minerals such as
calcium, Ca2+, and magnesium, Mg2+ and can help
conduct electricity. However, what needs to be noted
here is that not all water is the same nor will it conduct
electricity at the same rate.
The valve which locates in the lower part of CSTR
prevents the water coming down from the reactor so
that by opening it the conductivity will remain the same
even after a long time.

21. References:
1.http://www.lenntech.com/applications/ultrapure/co
nductivity/water-conductivity.htm
2.http://humantouchofchemistry.com/does-distilled-
water-conduct-electricity.htm
3.http://www.ovguide.com/continuous-stirred-tank-
reactor-9202a8c04000641f800000000070b37d
4.https://controls.engin.umich.edu/wiki/index.php/PID
StandardNotation