Chemical Engineering Assignment Solution - Complete Analysis

This document provides a comprehensive solution to a chemical engineering assignment, addressing key concepts and problems. The assignment covers a range of topics, including the definition of Parachor and Refrachor, examples of first-order reactions, types of electrodes and systems, and the first law of thermodynamics. It further explores conditions for precipitation based on Ip and Ksp, differentiates between molecularity and order of reactions, and explains exothermic processes. The solution also delves into methods for determining viscosity and surface tension, such as Ostwald’s method and the drop pipette method, and explores the common ion effect and endothermic reactions. Conductometric titration and solution preparation methods are also discussed, along with industrial applications of sulfuric acid and colloids, and the second law of thermodynamics.

Running head: CHEMICAL ENGINEERING 1
Chemical Engineering
Student’s Name
Name of Institution

CHEMICAL ENGINEERING 2
Q 1.
1. Sodium chloride and Zinc powder
2.
3. Parachor is a quantity defined by surface tension (y), molar mass (M), and density (d)
according to the formula; P= y
1
4 M
d

CHEMICAL ENGINEERING 3
Refrachor is a new physical constant for a yellow-like compound which does not dissolve in
methanol.
4. The hydrolysis of anticancer drug cisplatin.
The reaction of t-butyl bromide with H2O resulting in t-butanol.
5. The two types of electrodes are cathodes and anodes. Anodes attract negatively charged
anions while positively charged cations are attracted to the cathodes. The main material
for these electrodes is such metals as zinc and platinum.
6. An isolated system – it cannot use its surrounding to transfer energy or matter. Only the
universe exists as an isolated system in practice.
A closed system – it can use its surrounding to transfer energy but not matter. An adiabatically
isolated system allows work but not heat to be transferred while a mechanically isolated
system allows heat but not work to be transferred.
An open system – a system that uses its surrounding to transfer both energy and matter.
7. ∆ U =Q−W
Where; ∆U= change in internal energy
Q= the amount of heat added
W= work done by the system
8. The following is general rule for assigning signs; energy entering the system is given a
positive sign. Whenever work is done on the system, the sign given is positive. When
work is done by the system it is given negative sign.
9.

CHEMICAL ENGINEERING 4
10. There are two conditions for precipitation considering Ip and Ksp. The nature of the
solution and the possibility of precipitation. If the ion product is less than the Ksp then
the solution is unsaturated in nature and no precipitation can occur. If ion product is equal
to Ksp then the solution is saturated and being at equilibrium cannot experience

CHEMICAL ENGINEERING 5
precipitation. When Ksp is more than the ion product the solution becomes
supersaturated and thus allows precipitation to occur.
Q 2.
a. Molecularity is a single-step reaction where a number of molecules join to react. It is the
total of reactants of stoichiometric coefficients in this elementary reaction. On the other
hand, order or reaction is the total of the powers of the concentration of reactants in the
rate equation of that specific chemical reaction.
b. An exothermic process is a chemical reaction where energy is released in the form of heat
or light. An example of exothermic reaction is the nuclear explosion. The nuclear
explosion happens due to the increased release of energy from a fast-nuclear reaction.
These nuclear explosions produce radiation and radioactive debris.
c. Closed system - this is a system that does not permit various types of movements, for
example, transfer of mass in or out of the system. The transfer of energy is however
allowed. An example of a closed system is when a lid is put a beaker.
Open system – this system exchanges heat and work with the environment. For example, the
living system which can achieve a local decrease in their entropy during their growth and
development. They form structures of higher internal energy from the absorbed nutrients.
Isolated system – in this system no exchange of matter or energy occurs outside the boundaries
of the system. Either the system is too distant from other systems or it may be enclosed to
disallow energy or matter from neither entering nor existing. Soup poured in an insulated
container is an example of an isolated system.
d.

CHEMICAL ENGINEERING 6
OR
Q 2.
a. To determine viscosity using Ostwald’s method, an instrument known as the Oswald
viscometer is used. This method entails measuring the time that the established volume of
the liquid takes to flow via the U-tube under the influence of gravity. Materials of known
viscosity such as pure water are used to calibrate the instrument. In this case, the
viscosity of other liquids can be calculated from the known value of viscosity of one
liquid.

CHEMICAL ENGINEERING 7
b.
c. The drop pipette method is used to calculate surface tension by measuring the weights of
drops of a fluid of interest falling from a capillary glass tube. The weight of the falling
drops can be calculated by counting them.
d.

CHEMICAL ENGINEERING 8
Q 3.
a. The solubility of an ionic compound reduces significantly whenever a solution of an ionic
substance comes into contact with a different ionic compound of a common ion. For
instance, trying to dissolve table salt in a solution carrying the chloride ion. In this case,
the saturation point of the table salt would be lowered. This phenomenon is the common
ion effect. It plays a significant role in environmental and pharmaceutical areas.
b. H2S is applied in the qualitative analysis of inorganic salts and mixtures.
c. Isophobic sols are those where the phase that is dispersed has no attraction for the
dispersion solvent or medium. On the other hand, when colloids of isophilic sols are

CHEMICAL ENGINEERING 9
mixed with a preferable liquid, large forces of attraction exist between the colloidal
particles and the liquid.
d. An endothermic reaction is one that one that utilizes energy from its surrounding, mostly
in the form of heat. The endothermic reaction requires the breaking of a bond thus there
must be input of energy for the same. An example of endothermic reaction is the melting
of ice. The bond between the molecules is weakened and broken down for the ice matter
to change from solid state to liquid state. This bond breaking requires energy input and
hence an endothermic reaction.
Q 4
a.
b. Fig 1. The conductometric titration graph

CHEMICAL ENGINEERING 10
As shown above on the conductometric titration graph, when a strong acid reacts with a strong
base, a neutralization reaction occurs. As the base is added, the solution keeps getting
neutral until it starts turning into a base up to a point of saturation.
c. There are two methods of preparing solutions. The first method is by dissolving a decided
amount of solute in a solvent. The most used solute are solids. The concentration of the
resulting solution is determined by molarity, which is the number of moles of solute in
every liter of the solution. For example, to prepare a liter of sodium chloride with one
mole concentration, you first calculate the mass of a mole of sodium plus a mole of
chlorine. Next, you add place the sodium chloride in a volumetric flask. The flask should

CHEMICAL ENGINEERING 11
be 1 liter in volume. You then add a little distilled, deionized water to help the salt
dissolve before you fill the jar with water. The resulting solution is a concentration of a
mole of sodium chloride in a liter of water.
The other method is by diluting a given amount of solution with another solution of known
concentration of a solute. For instance, a liter of salt solution with a concentration of 2
mols per liter when mixed with three liters of water results in 4 liters of salt solution with
a concentration of 0.5mol/liter.
Q 5
a. Majority of the sulfuric acid produced is used in the manufacture of fertilizers. This is
achieved by reacting ammonium hydroxide solution with sulfuric acid to form
ammonium sulfate.
Sulfuric acid is used in the manufacture of detergents and paint
Ammonia also works as a refrigerant gas helping in the purification of water supplies, and in the
production of plastics, explosives, pesticides, dyes, textiles and various other chemicals.
b. The following are industrial applications of colloids
⮚ Water purification. Since colloidal impurities are found in water, an electrolyte
like alum can be used to weed out the impurities. The negatively charged colloidal
get attracted to the alum which is positively charged. Pure water is then decanted
off after the neutralized particles settle down.
⮚ Food items. Food stuffs such as milk, butter and ice cream contain colloidal
substances which are removed by the positively charged alum.

CHEMICAL ENGINEERING 12
⮚ Medicine. To raise the vitality of human system, colloidal calcium and gold are
administered to the human body by injection.
⮚ Sewage disposal. Dirt and mud particles have electrical charges. Electric field is
applied in sewage tank forcing the dirt particles to reach the oppositely charged
electrode where they get neutralized then coagulated. The coagulated particles are
then easily removed after they are suspended in the solution.
⮚ Smoke precipitation using Cottrell precipitator. The main source of pollution in
the big industrial cities is smoke and dust. Colloidal application enables the
precipitation of the smoke particles in the air. The electrically charged smoke
particles are weeded out by the Cottrell precipitator which uses the principle of
electrophoreses.
c.
pH =−log (NaOH )
pH =−log (0.02)
pH=1.7 pOH =14−pH =14−1.7=12.3
d. The second law of thermodynamics states that the sum entropy of an isolated system
cannot reduce over time, and is constant if and only if all the processes are reversible.
Isolated systems spontaneously evolve towards thermodynamic equilibrium, the state
with maximum entropy. In ideal cases where the system is in thermodynamic
equilibrium, its total entropy ant that of the surrounding can remain constant. In all the
occurring processes, such as the spontaneous processes, the total entropy of the system
and its surrounding increases and the process is irreversible in the dynamic sense.