İzmir Institute of Technology
CHEMICAL ENGINEERING DEPARTMENT
2008-2009 Spring Semester
CHE 310
CHEMICAL ENGINEERING LABORATORY I
Chemical Reaction
CHEMICAL REACTION
I.
OBJECTIVE
The objective of this experiment is to study a fast ionic chemical reaction of
sodium soap with magnesium sulphate, calculate mass and energy balances for the
process.
II.
PRINCIPLE and THEORY
Chemical equation
Under appropriate conditions, feed materials may be transformed into new and
different materials which constitute different chemical species. If this occurs only by
rearrangement or redistribution of the constituent atoms to form new molecules it is
said that a chemical reaction has occurred. A chemical reaction can be shown in short
form as a chemical equation;
∑ A i νi = 0
where;
…………………………………………………...…..(1)
A i is the substance i
ν i is the stoichiometric coefficient
ν i >0 for product
ν i <0 for reactant
Figure 1 shows the successive treatment steps in chemical process.
Raw
Materials
Physical
Chemical
Physical
Treatment
Treatment
Treatment
Steps
Steps
Steps
Products
Recycle
Figure 1: Typical Chemical Process
Equilibrium Constant
The equilibrium constant of a chemical reaction is;
K= Π [A i]νi
…………………………………………………..…………….(2)
where; A i is the concentration of the component A i in mol/dm 3
Rate of Reaction
The rate of change in number of moles of component Ai due to reaction is the
2
reaction rate. The rate of a chemical reaction:
r = (-1/ ν 1 ) (d[A 1 ]/ dt)= (-1/ ν 2 ) (d[A 2 ]/dt)
…………………(3)
depends on the concentration of the reactants and temperature.
ri= k [A 1 ]α [A2 ] β
.................…………………………………………..(4)
where; k is the rate constant
A 1 and A 2 reactants
α and β are the orders of the reaction with respect to A 1 and A 2. For simple
reaction α = ν 1 and β = ν 2
As an example of chemical reaction water insoluble metal soap will be
obtained from water soluble sodium soap and metal salt.
2(R-COONa) + MSO 4  (R-COO) 2 M + Na 2 SO 4 ..................................(5)
The solubility of NaSt is vitally important in this reaction. Its solubility i s given in
Figure 2. Solubility of NaSt increases with temperature above 60 C. At 70 C
solubility is 4 %, at 72 C it is 15 %. This reaction should be carried out above 72 C
to obtain highly concentrated NaSt solution and minimize water consumption.
Figure 2. Krafft boundaries of long chain soaps in aqueous solution, Data
NaSt (), NaAr (), NaBe () (Mul et al., 2000).
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III.
EXPERIMENTAL STUDY
Chemicals
Sodium stearate, magnesium sulphate and distilled water.
Experimental Procedure
- Before the experiment you should know which equipments, glassware and
instruments will be used during the experiment.
- Find the Material Safety Data Sheet (MSDS) for the chemicals.
- What are the application areas of magnesium stearate?
- What are the other production techniques of magnesium stearate?
Production of MgSt 2
1. 2, 5 % (w) sodium soap is obtained by dissolving 5 gram sodium stearate
in 200 ml of water at 70 o C.
2. Equivalent amount of magnesium sulphate is dissolved in 100 ml of water
3. Metal salt solution at 25°C is mixed with 200 ml of soap solution at 70°C
and reaction is carried out at 80°C, according to equations below (complete the right
hand-side of the equation)
2(C 17 H 35 COONa) (aq) + MgSO 4 .7H 2 O (aq) .........................................(6)
4. The precipitate obtained as a result of the reactions given above is left for a
while to settle.
5. Solid and liquid phases are separated after precipitation, solid particles are
removed by conventional filtration process, and filtrate conductivity is recorded.
6. In order to increase the purity magnesium stearate obtained, it is washed
twice to remove by-product Na 2 SO 4 using 100 ml distilled water, and conductivity of
the filtrate is recorded.
7. The wet solid, MgSt 2, taken from the filter is weighed and its weight is
recorded.
Characterization of MgSt 2
Before the characterization you should know the answers of the following
questions:
- What are the working principles of FTIR?
- Why do we use?
- What do we obtain at the end of the analysis?
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8. 1 g of MgSt 2 is dried in a moisture analyser to determine its water content.
Rest of MgSt 2 will be dried in circulating oven at 80 C.
9. Take IR spectrum of the dried product.
IV.
EVALUATION of EXPERIMENT
1. Explain why MgSt 2 precipitates when 200 ml sodium soap and 100 ml
MgSO 4 . 7H 2 O solution are mixed.
2. Determine the weight of MgSt 2 produced and compare it with the
theoretically calculated MgSt 2 amount from the Equation 6
3. Draw the block diagram of the process.
4. Perform the mass balance around the process.
5. Calculate the energy requirement for producing 1 kg magnesium stearate
considering heat inputs for heating soap solution and for drying.
6. Write down the equilibrium expression for reaction equation 6 and
solubility product equation for MgSt 2 (Chang, R.)
7. What is the rate expression for reaction equation 6?
8. How can you determine the purity of the MgSt 2 produced?
9. Find the characteristic IR peaks of magnesium stearate (MgSt 2 )
Acknowledgement: Author thanks Dr. D.Balköse for her helps in preparing this
manual.
V.

REFERENCES
Levenspiel O., “Chemical Reaction Engineering”, 2 nd Edition, John Wiley & Sons
pp 357-376, Toronto, 1972

Chang R., “Chemistry”, 5 th Edition, McGraw-Hill, pp. 125-135, Princeton

Mul M. N. G., Davis H. T., Evans D. F., Bhave A. V., and Wagner J. R.,
“Solution phase behavior and solid phase structure of long chain sodium soap
mixtures”, Langmuir, 16, 8276-8284, 2000.
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