LOGO MASS AND ENERGY BALANCES Wa Ode Cakra Nirwana, ST., MT. Chemical Engineering Department Engineering Faculty University of Brawijaya Presented by
LOGO
MASS AND ENERGY BALANCES
Wa Ode Cakra Nirwana, ST., MT.
Chemical Engineering DepartmentEngineering Faculty
University of Brawijaya
Presented by
LOGO
Introduction
LOGO
Aspek penilaian Unsur penilaian PresentasePemahaman Tugas 20 %
Quiz 1 dan 2 @ 20 %Ujian Akhir Semester (UAS) 30 %
Softskill Kreativitas dalam diskusi, kedisiplinan pengumpulan tugas, partisipasi di kelas, dsb
10 %
Tata Cara Penilaian
LOGO
Chemical Engineering Calculations
LOGO
Unit & Dimension
Dimensions: our basic concepts of
measurements such as length, time, mass,
temperature and so on
DEFINITION
Unit: expressing the dimensions, such as feet or centimeters for length, or hours or seconds for time
You can add, substract or equate numerical quantities only if the units of thequantities are the same
5 kg + 2 J
Example
Can not carrried out because the units of the two tems aredifferent
10 lb + 5 gr Can be performed (because the dimensions are the same, mass)Only after the units are transformed to be the same, either lb, gr and so on
LOGO
Example:
Add the following:a) 1 ft + 3 sb) 1 hp + 300 W
Solution:
Add the following:a) 1 ft has the dimensions of length whereas 3 s has the dimensions of time, so it
has no meaning since the dimensions of the two terms are not the same
b) 1 hp + 300 W The dimensions are the same (energy per unit time) but the units are different.The two quantities must be transformed into like units, such as hp or watts before the addition can be carried out.1 hp = 746 watts 1 hp + 300 W = 746 W + 300 W = 1046 W
LOGO
Physical Quantity
Name of Unit Symbol for Unit
Definition of Unit
BASIC SI UNITS
Length meter m
Mass kilogram kg
Time second s
Temperature Kelvin K
Amount of substance
mole mol
DERIVED SI UNIT
Energy joule J kg.m2.s-2
Force newton N kg.m.s-2 or J. m-1
Pressure Newton per square meter, pascal
N.m-2, Pa
Heat capacity Joule per (kilogram.kelvin)
J.kg-1.K-1
LOGO
Physical Quantity
Name of Unit Symbol for Unit
BASIC AMERICAN SYSTEM UNITS
Length feet ft
Mass pound lbm
Force pound lbf
Temperature Degree Rankine 0R
Time Second, hour s, hr
DERIVED AMERICAN SYSTEM UNIT
Energy Foot pound (force) Btu, (ft)(lbf)
Power horsepower hp
Pressure Pound (force) per square inch Lbf/in2
Heat capacity Btu per pound (mass) per degree F
Btu/(lbm.0F)
LOGO
Conversion of Units and Conversion Factors
Conversions factors are statements of equivalent values of different units in the same system or between systems of
units
The concept is to multiply any number and its associated units with dimensionless ratios termed
conversion factors to arrive at the desired answer and its associated units
Example:
Solution:
If a plane travels at twice the speed of sound (assume that the speed of sound is 1100 ft/s), how fast is it going in miles per hour?
LOGO
Conversion of SI units is simpler than conversions in the American Engineering system
Example: We use Newton’s Law to compare the respective units:F = Cma
F = ForceC = a constant whose numerical value and units depend on those selected for F, m and am = massa = acceleration
SI Unit:
American Engineering System:
In the SI system, unit of force is newton (N) if C = 1 N/(kg)(m)/s2 then when 1 kg is accelerated at 1 m/s2
In the American Engineering system, unit of force is pound (force), (lbf) if C then when the inverse of the conversion factor with the
Numerical value 32.174 included is given the secial symbol gc
LOGO
Note:The pound (mass) and pound (force) are not the same units in the American Engineering system
Example:
Solution:
One hundred pounds of water is flowing through a pipe at the rate of 10.0 ft/s. What is the kinetic energy of this water in (ft)(lbf)
Kinetic energy = K = ½ mv2
Assume that the 100 lb of water means the mass of the water
LOGO
Dimensional ConsistencyA basic principle exists that equations must be dimensionally consistent
The principle: Each term in an equation must have the same net dimensions and units as every other term to which it is
added or substracted or equated
Dimensional considerations can be used to help identity the dimensions and units
of terms or quantities in an equationExample:
The microchip etching roughly follows the relation:d is the depth of the etch in µm and t is the time of the etch in seconds. What are the units associated with the number 16.2 and 0.021? Convert the relation sothat d becomes expressed in inches and t in minutes! Solution:
Both values of 16.2 must have the units of microns. The exponential must be dimensionless So that 0.021 must have the units of 1/s
LOGO
The mole Unita mole is a certain number of molecules, atoms, electrons or other specified types of particles.
In the SI a mole is composed of 6.02 x 1023 molecules g mol is equal to mole
The g mol = mass in g molecular weight
The lb mol = mass in lb molecular weight
Mass in g = (mol. wt)(g mol)
Mass in lb = (mol. wt)(lb mol)
Example:
Solution:
If a bucket holds 2.00 lb of NaOH (mol.wt. = 40.0), how many(a) Pound moles of NaOH does it contain(b) Gram moles of NaOH does it contain
OR
LOGO
Conventions In Methods of Analysis and Measurement
DensityDensity is the ratio of mass per unit volume (kg/m3 or lb/ft3)Density for liquids and solids do not change significantly at ordinary conditions with pressure but they do change with temperature
Specific GravitySpecific gravity is a dimensionless ratio that can be considered as the ratio of two
Densities – that of the substance of interest, A, to that of a reference substance
The reference substance for liquids and solids is normally waterThe specific gravity of gases frequently is reffered to air or maybe referred to other gases
LOGO
Example:
Solution:
LOGO
Specific VolumeThe spesific volume of any compound is the inverse of the density, that is, the
volume per unit mass or unit amount of material. Units of specific volume might be ft3/lbm, cm3/g, m3/kg.
Mole Fraction and Mass (Weight) Fraction
LOGO
Example:
Solution:
LOGO
Analyses
Example:
Solution:
LOGO
Concentration
LOGO
Example:
Solution:
The current OSHA 8 hours limit for HCN in air is 10 ppm. A lethal dose of HCN in air(from the Merck Index) is 300 mg/kg of air at room temperature. How many mg HCN/kg air is the 10 ppm? What fraction of the lethal dose is 10 ppm?
Basis: 1 kgmol of the air/HCN mixture
The 10 ppm is because the amount of
HCN is so small. Then
(a)
(b)
LOGO
Example:
Solution:
LOGO
LOGO
NOTESIt is important to remember that in an ideal solution, such as in gases or in
a simple mixture of hydrocarbon liquids or compounds of like chemical nature, the volumes of the components maybe added without great error to get the total volume of the mixtureFor the so-called nonideal mixtures this rule does not hold and the total volume
of the mixture is bigger or smaller than the sum of the volumes of the pure components
LOGO
Basis
LOGO
Example:
Solution:
LOGO
Example:
Solution:
LOGO
LOGO
LOGO
Temperature
Temperature Scales
LOGO
LOGO
Example:
Solution:
LOGO
Pressure
LOGO
LOGO
LOGO
Example:
Solution:
NOTES
LOGO
LOGO
LOGO
LOGO
LOGO
NOTES
LOGO
Example:
Solution:
LOGO
Example:
Solution:
LOGO
The Chemical Equation and Stoichiometry
LOGO
LOGO
Example:
Solution:
LOGO
LOGO
NOTES
Example
LOGO
LOGO
LOGO
If more than one product and more than one reactant are involved, the reactant upon which the yield is to be based must be clearly stated. Supposethat we have a reaction sequence as follows:
LOGO
Example:
Solution:
LOGO
LOGO