INTRODUCTION • A drug is administered to a patient as a

specific drug product which is particular dosage

Pharmaceutics
form.
• Branch of Pharmaceutical Sciences that deals
• A dosage form is most often a formulation of
with the study of the following:
the drug with various excipients.
⚬ Investigation of physical and chemical • Drug products can be formulated in a variety
properties of drug molecules. of dosage forms and can be administered in
⚬ Design, fabrication, and evaluation of Drug different routes of administration.
Delivery Systems. • Drugs that are administered in a certain route
should be absorbed in order for them to
⚬ Monitoring of how the drug is absorbed,
become bioavailable to the systemic circulation.
distributed, metabolized, and excreted in the
body. PHARMACOKINETICS (what your body is doing
to the drug)

Absorption – distribution – biotransformation

PHYSICAL PHARMACY
– excretion (ADME)
”INVESTIGATION OF PHYSICAL AND CHEMICAL
Monitoring of how the drug is absorbed,
PROPERTIES OF DRUG MOLECULES”
distributed, metabolized, and excreted in the
body.

Physical Properties BIOPHARMACEUTICS (what drug does to your

body)
• Physical form • Particle size
Study of the physicochemical properties of
• Solubility & Dissolution • Melting point
drugs and their proper dosage form as related
• Partition Coefficient • Refractive index to the onset, duration, and intensity of drug
action.
• Specific Gravity
Physical form-
• Can be crystalline or amorphous form.
Chemical Properties (describes the way the Crystalline is the most common form of
substance react to form other substances) solid, it has regular shape and pattern,
and has very narrow BP and MT point.
• Chemical structures • Optical Activity Amorphous has irregular shape, doesn’t
• Polymorphism • Ionization distinct solid and liquid form because of
lack of characteristic geometry.
• Complexation and Protein binding • It can be in liquid like injection form and
particular solid dosage form
Particle size
• It can be tablet, capsule, granules,
• Design, fabrication, and evaluation of Drug suspension, that’s why there’s a specific
Delivery Systems. particular size for each type of dosage
form. Particle size can also affect the
 dissolution of substance with lower important because it actually the one
particle size they dissolve fast. has therapeutically active, it has ability
• It also affect the stability of colloid, if to reduce morning sickness in pregnant.
the particle is small it tend to have Levorotatory is ineffective.
sedimentation. • Problem of dextrorotatory form of
• Affects disintegration time of tablet. dopamine, it cannot pass through in
Disintegration or liberation is a rate blood vein barrier and it cannot go in
limiting step of ADME. active site so it cannot bind so it can’t
• Affects absorption, distribution, elicit effect.
metabolism and elimination. • In levorotatory can passed through
Solubility & Dissolution blood vein barrier and it’s called
• Before your drug absorb to your body, “levodopa”
it should be solution. Solubility has Polymorphism
solute, solvent, and solution. Solute • Allotropes or polymers has different
small amount of substance. Solvent stability, so 1 allotrope may be more
larger quantity (water). Solution stable than the other and they also
concentration is depend on the have a specific temperature wherein
solubility on solute to the chosen they are more stable.
solvent. pH and Ionization
Melting point • When you combine acid base it become
• Temperature where the solid and liquid ionize. Drug only become absorb if it’s
phase is in equilibrium and affected by an ionized form. Drug may be acidic or
different forces of attraction between basic drug.
molecules. • If you want that your drug is acidic drug
Partition Coefficient to remain an ionized you have to
• Measure of drug concentration in maintain the environment of drug in
nonpolar. acidic media. Like acidic and the
• Membrane has different barrier. Drug environment is basic to ionize.
passed through lipid bilayer. Partition
coefficient is a most commonly use way
Dimension and units
to define hydrophilic and if it pass
through lipid bilayer. Fundamental dimension
Refractive index
Dimension Symbol CGS SI Reference
• Measure of how much the speed of
unit unit standard
light bend inside a medium.
Refractometer Length L cm m m
Mass M g kg kg
Chemical structures
Time T sec s Atomic
• Affects the therapeutic activity of
frequency of
substance
cesium 133
Optical Activity
• 2 form: dextrorotatory and levorotatory
for chiral substances. Dextrorotatory is
 Derived dimensions and units • These are the errors that can case the
measures mean value in any serious
Dimension Dimensi CGS unit SI unit Relation to
onal other measures to be displaces in particular
Symbol dimension direction.
Area (A) L cm2 m2 Square of L • Determinate error can occur in a
Volume (V) L cm3 m3 Cube of L constant moment in serious
Density (D) mL-3 g/cm3 Kg/m3 Mass over determination. It is usually detectable
unit volume and can correct.
• INSTRUMENTATION ERROR. Can occur
Velocity (V) LT-1 cm/s m/s Length
due to failure of calibration (we can
overtime
correct by periodic calibrating.),
degradation of different part of
Derived dimensions and units instrument (can correct by proper
maintenance), variation in temperature.
Dimension Dimensional CGS SI Relation to
Symbol unit unit other • METHOD ERROR. Incorrect sampling,
dimension contamination of precipitate, improper
Acceleration L cm2 m2 Square of L selection of indicator. Can correct by
(a) developing proper method.
Force (F) L cm3 m3 Cube of L
• PERSONAL ERROR. Due to the
Pressure (p) mL-3 g/cm3 Kg/m3 Mass over unit
individual analyst for example the
volume
analyst to judge color. It can be
Energy (E) LT-1 cm/s m/s Length minimize by proper training and
overtime experience.
Derived L cm2 m2 Square of L
dimensions How to detect determinate errors?

- We can use analysis of standard solution,

independent analysis, and blank determination.
ERRORS

• May be defined as a deviation from the INDETERMINATE ERROR (accidental error)

absolute value or from the true average of a
large number of results. • It is an error that cause the measured
value for its measurement to be scan
TYPE OF ERRORS: randomly about the error.
Indeterminate error are accidental in
• Determinate Errors
nature or by chance. They usually
• Indeterminate Errors manifest themselves by slight variation
on an observation made by an
• Pseudo-accidental or Variable Determinate
observers under identical condition.
Errors
• Limitations of reading balances, scales
DETERMINATE ERROR such as rulers or dials, and electrical
“noise” in instruments.
Instrumentation, method, personal errors
PSEUDO-ACCIDENTAL/ VARIABLE DETERMINATE STATES OF MATTER
Binding forces between molecules
• They arise from random fluctuation in Manifestations of Intermolecular forces:
temperature or other external factors, • Repulsive and Attractive forces
changes in pH • Cohesion – attraction of like molecules
• These errors can be reduce by • Adhesion – attraction of unlike molecules
controlling condition through the use of Premises:
constant temperature and oven. And In intermolecular forces- when molecules
you may maintain humidity, pressure of interact both the repulsive and attractive
environment. operate. And 2 molecules are both brought
close together the opposite charges in this 2
molecule are close together than the light
charges and causes the molecules to attract one
another. When the molecules brought so close
that the other charge, the molecule repel each
other.
• Attractive forces are necessary in order that
molecules cohere/adhere.
• Repulsive forces are necessary in order that
the molecules do not interpenetrate one
another.
• Repulsion is due to the interpenetration of
the electronic clouds of molecules and
increases exponentially with a decrease in
distance between the molecules.
PRECISION AND ACCURACY
• At certain equilibrium distance, about 3 or 4x
Precision is the degree to meets your 10-8 cm (3 or 4 angstroms), the repulsive and
measurements not meet around the central attractive forces are equal
measurement. It about reproducibility and
repeatability. 1. Van der Waals Forces – these relates to non-
ionic interaction between molecules. They
Types of Precision: involve non-ionic interaction still, they involve
charge interactions. Van der Waals interaction
• Repeatability is weak forces that involves dispersion of
• The precision when a single analyst charges across a molecule called “dipole”
completes the analysis in a single • Keesom Forces (dipole-dipole interaction) –
session using the same solutions, polar-polar. The permanent dipole interacts
equipment, and instrumentation. with one another in an ion like fashion.
• Reproducibility However the charges are partial the strength of
• The precision under any other set of bonding is weaker than ionic bond. The dipole-
conditions, including between analysts, dipole forces increases as the polarity of the
or between laboratory sessions for a molecule increases. Approximate (1kg/c/m).
single analyst. Substances involve are Water and hydrochloric
acid, alcohol, acetone and phenol
• Orientation Effect
• Attraction between polar molecules
• Strongest
• Debye Forces - permanent dipole are actually • Because of the small size of hydrogen atom, it
capable of inducing and electric dipole in can move in close to the electronegative atom
nonpolar molecules. Involves attraction and form an electrostatic type of union known
between nonpolar and polar molecules. Polar as a hydrogen bond or hydrogen bridge.
molecules can induce and electric dipole and • It can exist as Intramolecular and
can induce polarity to your nonpolar molecules. Intermolecular forces of attraction.
The dipole is for polar molecule and induced
dipole is for nonpolar molecule 5. Hydrophobic Interactions – low water soluble
• Induction effect molecules. It is a Nonpolar molecule
• Attraction between nonpolar and • Forces of attraction between nonpolar atoms
polar molecules and molecules in water.
• London Forces- nonpolar molecule can induce • They cause the nonpolar species to be driven
polarity in other nonpolar by induced dipole. It together and are critical for the structure and
is temporary attractive forces that results when stabilization of many molecules including
the electrons in 2 neighbor atoms occupy proteins (with non-polar amino acids) and
position that makes the atom form temporary aggregates of amphiphiles.
dipoles. Substance: Carbon disulfide, carbon
tetrachloride, and hexane. Phases/ Intermolecular Volume Shape movemen
States Forces of t
• Attraction between nonpolar attraction
molecules solid Strongest definite Definite vibration
• Weakest (0.5 – 1 kg/calories/mole) Liqui Strong definite Indefini Gliding/
te flowing
d
2. Ion-induced dipole forces Gas Weakest Indefinit Indefini Constant
e te random
• Attractions occur between nonpolar motion
molecules and ions.
• Ion- induced dipole forces are involved in the Physical Changes
formation of the iodide complex. • Melting/fusion – solid to liquid
• These types of interactions account in part for • Evaporation – liquid to gas
the solubility of ionic crystalline substances in • Condensation – gas to liquid
water. • Freezing – liquid to solid
• Sublimation – solid to gas
3. Ion-Dipole Forces- result of electrostatic • Deposition – gas to solid
interaction between a charge ion and a
molecule that has a dipole. It is attractive forces GASEOUS STATE
that is commonly found in solution especially in Characteristics of Gases
ionic compound dissolves in polar liquids. • Higher kinetic energy – form of energy that an
• Attractions occur between polar molecules object or particle has by reason of its motion.
and ions. • Held together by weak intermolecular forces.
• Have no regular shape.
• Compressible
4. Hydrogen Bonding – interaction containing a • Invisible
hydrogen, nitrogen and strongly
electronegative atom (fluorine, oxygen, and
nitrogen) GAS LAW
• It is a special type of dipole-dipole in which 1. Boyle’s Law
hydrogen is bonded to an electronegative • relates the volume and pressure of a given
element. mass of gas at constant temperature.
 2. A balloon full of air has a volume 2.75 L at a
temperature of 18 ºC. What is the balloon’s
volume at 45 ºC?

When volume increases, the pressure decreases

Examples:
1. A sample of nitrogen collected in the
laboratory occupies volume of 725 ml at a
pressure of 0.971 atm. What volume will the
gas occupy at a pressure of 1.40 atm, assuming
the temperature remains constant?
2. A sample of neon gas occupies a volume of
2.8 L at 1.8atm. What will its volume be at 1.2
atm?

3. Gay-Lusaac’s Law
• states that the pressure and absolute
temperature of a given mass of a gas at
constant volume are directly proportional.

Charles’s Law
• states that the volume and absolute
temperature of a given mass of a gas at
constant pressure are directly proportional.
Examples:
1. A cylinder of gas has a pressure of 4.40 atm
at 25 ºC. At what temperature in ºC will it reach
a pressure of 6.50 atm?
2. A mylar balloon is filled with helium gas to a
pressure of 107 kPa when the temperature is 22
ºC. If the temperature changes to 45 ºC, what
Examples:
will be the pressure of the helium in the
1. A container of oxygen has a volume of 349 ml
balloon?
at a temperature of 22 ºC. What volume will the
gas occupy at 50 ºC?
 5. Ideal Gas Law
4. Combined Gas Law • Infinite volume = non-attracting molecules
• The summary of the relationship of the three R= 0.08205 L.atm/mol.k
gas laws presented earlier.

Examples:
Examples: 1. What is the volume of 2 moles of an ideal gas
1. In the assay of ethyl nitrite spirit, the nitric at 25°C and 780 mm Hg?
oxide gas that is liberated from a definite 2. What mass of CO2 is need to fill a L tank to a
quantity of spirit and collected in a gas burette pressure of 150 atm at 27°C?
occupies a volume of 30.0 ml at a temperature
of 20°C and a pressure of 740mmHg of mercury.
What is the volume at 0°C and 760mmHg?
2. A sample of hydrogen gas has a volume of 65
ml at a pressure 0.992 atm and a temperature
of 16°C. What volume will the hydrogen occupy
at 0.984 atm and 25°C?
6. Avogadro’s Law 1. What pressure would a 131 g of xenon gas
in a vessel with a 1 L volume exert at 25°C if it
behaved as:

• An ideal gas?
• As a van der Waals gas?

a = 4.137 L2 atm mol-2

Examples:
1. 5 L of a gas is known to contain 0.965 mol. If b = 5.16x10-2 L mol-1
the amount of gas is increased to 1.80 mol,
what new volume will result?

2. A cylinder with a movable piston contains 2g 2. What pressure would a 25 g of argon gas in
of helium, He, at room temperature. More a vessel of 1.5 L volume exert at 30°C if it
helium was added to the cylinder and the behaved as:
volume was adjusted so that the gas pressure
remained the same. How many grams of helium • An ideal gas?
were added to the cylinder if the volume was • As a van der Waals gas?
changed 2 L to 2.70 L?
a = 1.337 L2 atm mol-2

b = 3.20x10-2 L mol-1

3. An ideal has undergone isothermal

compression, which reduces its volume by
2.20 L. The final pressure and volume of the
gas are 5.04 bar and 4.65 L, respectively.
Calculate the original pressure of the gas in
(a) bar, (b) atm.
 neon. The partial pressure of neon at 300 K is
8.87 kPa. Calculate the:
4. A sample of hydrogen gas was found to
have a pressure of 125 kPa when the • Volume of the mixture.
temperature was 23°C. What can its pressure • Total pressure of the mixture.
be expected to be when the temperature is
11°C?
7. Dalton’s Law of Partial Pressure
• The total pressure (Pt) is the sum of the
individual partial pressure of each component
5. A weather balloon rises 2 miles into the in the system.
upper atmosphere. Its volume at ground level
is 2.50 liters at 1 atm pressure and 24°C.
What is its final volume if the atmospheric
pressure is 8.77x10-3 atm and the
temperature is -44.7°C at the 2-mile position?
Kinetic Molecular Theory
• The theory developed to explain the behavior
of gases and supported the validity of the gas
6. If 0.50 g of the drug in the vapor state laws.
occupies 100 mL at 120°C and 1 atm • Some of the more important statements of
pressure, what is its approximate molecular the theory are the following:
weight? • Gases are composed of particles called
molecules, the total volume of which is so small
as to be negligible in relation to the volume of
the space in which the molecules are confined.
• The particles of the gas do not attract one
another but rather move with complete
independence.

• The particles exhibit continuous random

motion owing to their kinetic energy. The
average kinetic energy is directly proportional
to the absolute temperature of the gas.
• The molecules exhibit perfect elasticity, that
7. A small household fire extinguisher of 0.80- is, there is no net loss of speed after they collide
liter capacity contains CO2 at a pressure of with one another and with the walls of the
12.3 atm and 25°C. confining vessel, which latter effect accounts
for the gas pressure. Although the net velocity,
What is the weight of the CO2 in kg in the and therefore the average kinetic energy, does
extinguisher? not change in collision, the speed and energy of
the individual molecules may differ widely at
What is the volume of this mass of CO2 at any instant.
25°C when the pressure is reduced to 1 atm?
Van der Waals Equation for Real Gases
• For 1 mole of a gas, the Van der Waals
equation is written as:
8. A gas mixture consists of 320 mg of
methane, 175 mg of argon, and 225 mg of
For the more general case of n moles of gas in a forms a gas under normal atmospheric
container of volume, V, equation becomes conditions.

Equilibrium Vapor Pressure

• When the rate of condensation equals the
rate of vaporization at a definite temperature,
the vapor becomes saturated and a dynamic
equilibrium is established.
• It is the pressure of the saturated vapor above
• Polar liquids have high internal pressures and the liquid.
serve as solvents only for substances of similar
internal pressures. Vapor – is a substance that is liquid or solid at
• Nonpolar molecules have low internal room temperature and that passes into the
pressures and are not able to overcome the gaseous state when heated to a sufficiently high
powerful cohesive forces of the polar solvent temperature
molecules.
Relationship between Vapor Pressure and
LIQUID STATE Temperature
Critical Pressure • As the temperature of the liquid is elevated,
• pressure required to liquefy a gas at its critical more molecules approach the velocity
temperature, which is also the highest vapor necessary for escape and pass into the gaseous
pressure that the liquid can have state. As a result, the vapor pressure increases
with rising temperature.
Liquefaction of Gases • Manometer – device used to measure the
• Adiabatic expansion vapor pressure
• an expansion which allows an ideal
gas to expand so rapidly that no heat enters the SOLID STATE
system. - Solids hade definite shape and volume and
also has rigidity. Solid has high density and low
Liquefaction of Gases compressibility due to close packing of
• Joule – Thomson effect molecule which eliminates freeze space among
• This cooling effect is observed when a highly molecule.
compressed non ideal gas expands into a region
of low pressure. In this case, the drop in General Properties of Solids
temperature results from the energy expended • When a force is applied to a solid, it has a
in overcoming the cohesive forces of attraction fixed shape.
between the molecules. • They are nearly incompressible.
• They have strong intermolecular forces and
Aerosols very little kinetic energy.
• The basic principle involved in the preparation • Atoms in a solid vibrate about a fixed position.
of pharmaceutical aerosols is when pressure is • They are characterized by shape, size and
reduced, the molecules expand and the liquid melting point and a few have sublimation
revert to a gas. points.
• Characterized by surface energy, hardness,
Propellant elastic properties and compactability.
• A material that is liquid under the pressure
conditions existing inside the container but that
Classification of Organic solids based on Crystalline Solids
molecular morphology - has 7 crystal classes and those 7 classes has 14
bravais lattice (3D configuration into which the
• Crystalline Solids atom is arrange into crystals)
o Polymorphs • The structural units of crystalline solids, such
§ Monotropic as ice, sodium chloride, and menthol, are
§ Enantiotropic arranged in fixed geometric patterns or lattices.
o Hydrates/Solvates • Four types of Units Cells:
§ Reversible o Primitive (P) – not contain any internal atoms
§ Irreversible (atoms are in the corners)
o Salt crystals o Body centered (I) – contains an internal atom
o Co-crystals (in the middle of the cells)
o Face centered (F) – contains internal atom
• Amorphous Solids (middle of each phase)
o Amorphous o Side centered (C) (also known as “base
o Amorphous Dispersions center”)– contains internal atom (center of the
two opposite phases
• Polymeric
Crystalline Solids
• Are substances whose constituent atoms,
molecules, or ions are arranged in an ordered or
arranged in repetitious 3 dimensional lattice
units infinitely throughout the cell.
• The nature of unit cells (smallest group of
atom that forms the basic building blocks of the
crystals) have different properties such as
solubility, stability and compressibility.
• The macroscopic crystals can have different
geometric shape such as plates, needles,
blades, prisms and blocks (crystal habit)

Properties of Crystalline Solids Polymorphism- the ability of solid material to

• They have a sharp melting point. exist in more than 1 form or crystals structure.
• The strength of all the bonds between Also allotropic.
different ions, molecules and atoms are equal.
• They possess a definite geometrical shape. Categories of Polymorphs
• They have crystal symmetry. Enantiotropic
• They have lower solubility. • If one of the polymorph is the most stable
• They are more stable. over a certain temperature range while the
• They are anisotropic other polymorph is the most stable over a
different temperature range below the melting
-same property in all direction are said to be point.
“isotropic- amorphous” the properties of
amorphous has same properties. Monotropic
While the “anlisotropic” involves crystalline • If one polymorph is ALWAYS the most stable
solids, have directional differences in properties for all temperatures below the melting point,
with all the other polymorphs being less stable.
Polymorphs • Aside from solvents, crystal lattice can
accommodate other molecules, such as acids
Importance and Applications: and bases, to form salts.
• Preparation of a particular dosage form • If there is a pKa difference of two between
• eg. Theobroma oil (for the molecules, a proton is transferred to form
suppositories)/Cacao butter two ionized species.
• 4 polymorphs: • The two ionized species will interact with the
• Gamma form lattice to form a crystalline salt.
• Alpha form • The drug substance can be a weak acid or a
• Beta prime form weak base.
• Beta stable form
Polymorphs Manufacturing
• eg. Paracetamol and Ibuprofen
Stability of the Preparation

• Ritonavir
Ease of administration

• eg. Suspension for injections

Bioavailability
• polymorphs exhibits different properties that
may affect solubility and dissolution.
• eg: Chloramphenicol palmitate,
oxytetracycline

Co-Crystals (solvate)
DRUG NUMBER OF POLYMORPHIC FORM -when solvent is water it is called “hydrate”
Acetaminophen 3
Caffeine 2 Pharmaceutical Co-crystals
Chloramphenicol Palmitate 4 • They contain two or more distinct molecules
Cimetidine 3 arranged to create a new crystal form whose
Nifedipine 2 properties are often superior to those of each
Phenobarbital sodium 2 of the separate entities.
Phenytoin 2 • The pharmaceutical cocrystals are formed
Progesterone 2 between a molecular or ionic drug and a
Theophylline 2 cocrystal former that is a solid under ambient
conditions.
Pseudopolymorphs Examples:
• Solvents are trapped within a crystal lattice • Itraconazole : L-malic acid – antifungal and
structure through crystal engineering. poorly soluble (it does not easily mixed to a
• Solvents could be water or other solvents. solution
• The water/solvent is usually present in • Carbamazepine : saccharin cocrystal
stoichiometric ratios. • Fluoxetine : succinic acid cocrystal
• Importance/Applications:
• Improved solubility, stability and dissolution
rate (Bioavailability)

Salt Crystals
Amorphous Solids • Smectic – greaselike or soaplike (molecules
-crystalline are packed in repeated ordered are in 2 directions and can rotate in 1 axis,
fashion. Crystal has crystalattice (molecules solubilization of water insoluble materials)
held together by intermolecular forces) • Nematic – threadlike (rotates only at one
• May be considered as super cooled liquids in direction at one axis but the mobile in 3D
which the molecules are arrange in a random • Cholesteric – special type of nematic
manner somewhat as in the liquid state. (molecule are directional oriented in helical
• Examples: coal, glass, plastic and rubber pattern with 1 layer rotated and slight angle to
the 1 above it and bottom)
Properties: • Discotic- forms 1 dimensional columnar phase
• They have no sharp melting point. by stacking the molecule
• They don’t possess a definite shape.
• They don’t have crystal symmetry. Liquid Crystalline State
• They have higher solubility. Controlled release of bioactive materials
• They are less stable and can be prone to • Example of drugs that can be incorporated in
degradation and crystallization. liquid crystalline technology:
• The strength of different bonds is different in • Indomethacin
amorphous solids. • Clotrimazole
• They are isotropic. • Nitroglycerin
• They tend to flow when subjected to pressure • Lidocaine Hydrochloride
over a period of time. Latest development in Liquid crystalline
technology:
Amorphous • Apatone – used in chemotherapy
• The amorphous form of drug is more soluble • Olecine -
than the crystalline counterpart since there’s no
crystal lattice and it required less energy for
solubilization.
• Higher solubility can translate to
Bioavailability in some cases.
• Example of marketed drugs in amorphous
form: Zafirlukast, Cefuroxime axetil, Quinapril
HCl and Nelfinavir mesylate

Amorphous Dispersions
• The amorphous drug is stabilized by a polymer
or a combination of polymers or surfactants.
• Example of marketed drugs in amorphous
dispersion forms: Itraconazole (dispersed in Phase Rule
HPMC which is polymer and increased in J. Willard Gibbs formulated the Phase rule
solubility and icrease availability in 30%), • It is a useful device for relating the effect of
Ritanovir, Etravirine. the least number of independent variables
(temperature, pressure, and concentration)
Liquid Crystalline State upon the various phases (solid, liquid, gas) that
• They are the fourth state of matter. can exist in an equilibrium system containing a
• They can be formed by heating solids or the given number of components.
action of certain solvents • The phase rule is expressed as follows:
F=C–P+2
Types of liquid crystals:
In which:
F is the no. of degrees of freedom in the
system,
C is the no. of components, and
P is the no. of phases present

Phase Rule
Examples:
• Pure water / solid ice / water vapor
• Pure water and water vapor
• Pure water, water vapor and solid ice
• Liquid water, liquid alcohol and its vapor
• Liquid water, liquid benzyl alcohol and vapor
mixture