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Foundation

We have observed and defined phase transitions and phase equilibrium. We have also observed equilibrium in avariety of reaction systems. We will assume an understanding of the postulates of the Kinetic Molecular Theory and of the energetics of chemical reactions.

Goals

We have developed an understanding of the concept of equilibrium, both for phase equilibrium and reactionequilibrium. As an illustration, at normal atmospheric pressure, we expect to find H 2 O in solid form below 0°C, in liquid form below 100°C, and in gaseous form above 100°C. What changes as we movefrom low temperature to high temperature cause these transitions in which phase is observed? Viewed differently, if a sample of gaseouswater at 120°C is cooled to below 100°C, virtually all of the water vapor spontaneously condenses to form theliquid: H 2 O ( g ) H 2 O ( l ) spontaneous below100°C By contrast, very little of liquid water at 80°C spontaneously converts to gaseous water: H 2 O ( l ) H 2 O ( g ) not spontaneous below100°C We can thus rephrase our question as, what determines which processes are spontaneous and which are not? Whatfactors determine what phase is "stable"?

As we know, at certain temperatures and pressures, more than one phase can be stable. For example, at 1 atmpressure and 0°C, H 2 O ( s ) H 2 O ( l ) equilibrium at 0°C Small variations in the amount of heat applied or extracted to the liquid-solid equilibrium cause shifts towardsliquid or solid without changing the temperature of the two phases at equilibrium. Therefore, when the two phases are at equilibrium,neither direction of the phase transition is spontaneous at 0°C. We therefore need to understand what factors determinewhen two or more phases can co-exist at equilibrium.

This analysis leaves unanswered a series of questions regarding the differences between liquids and gases. Theconcept of a gas phase or a liquid phase is not a characteristic of an individual molecule. In fact, it does not make any sense torefer to the "phase" of an individual molecule. The phase is a collective property of large numbers of molecules.Although we can discuss the importance of molecular properties regarding liquid and gas phases, we have not discussed the factorswhich determine whether the gas phase or the liquid phase is most stable at a given temperature and pressure.

These same questions can be applied to reaction equilibrium. When a mixture of reactants and products isnot at equilibrium, the reaction will occur spontaneously in one direction or the other until the reaction achieves equilibrium.What determines the direction of spontaneity? What is the driving force towards equilibrium? How does the system know that equilibrium has been achieved? Our goal will be to understand the driving forces behind spontaneousprocesses and the determination of the equilibrium point, both for phase equilibrium and reaction equilibrium.

Observation 1: spontaneous mixing

We begin by examining common characteristics of spontaneous processes, and for simplicity, we focus on processesnot involving phase transitions or chemical reactions. A very clear example of such a process is mixing. Imagine putting a drop of blueink in a glass of water. At first, the blue dye in the ink is highly concentrated. Therefore, the molecules of the dye areclosely congregated. Slowly but steadily, the dye begins to diffuse throughout the entire glass of water, so that eventually the waterappears as a uniform blue color. This occurs more readily with agitation or stirring but occurs spontaneously even without sucheffort. Careful measurements show that this process occurs without a change in temperature, so there is no energy input or releasedduring the mixing.

Questions & Answers

what is microbiology
Agebe Reply
What is a cell
Odelana Reply
what is cell
Mohammed
how does Neisseria cause meningitis
Nyibol Reply
what is microbiologist
Muhammad Reply
what is errata
Muhammad
is the branch of biology that deals with the study of microorganisms.
Ntefuni Reply
What is microbiology
Mercy Reply
studies of microbes
Louisiaste
when we takee the specimen which lumbar,spin,
Ziyad Reply
How bacteria create energy to survive?
Muhamad Reply
Bacteria doesn't produce energy they are dependent upon their substrate in case of lack of nutrients they are able to make spores which helps them to sustain in harsh environments
_Adnan
But not all bacteria make spores, l mean Eukaryotic cells have Mitochondria which acts as powerhouse for them, since bacteria don't have it, what is the substitution for it?
Muhamad
they make spores
Louisiaste
what is sporadic nd endemic, epidemic
Aminu Reply
the significance of food webs for disease transmission
Abreham
food webs brings about an infection as an individual depends on number of diseased foods or carriers dully.
Mark
explain assimilatory nitrate reduction
Esinniobiwa Reply
Assimilatory nitrate reduction is a process that occurs in some microorganisms, such as bacteria and archaea, in which nitrate (NO3-) is reduced to nitrite (NO2-), and then further reduced to ammonia (NH3).
Elkana
This process is called assimilatory nitrate reduction because the nitrogen that is produced is incorporated in the cells of microorganisms where it can be used in the synthesis of amino acids and other nitrogen products
Elkana
Examples of thermophilic organisms
Shu Reply
Give Examples of thermophilic organisms
Shu
advantages of normal Flora to the host
Micheal Reply
Prevent foreign microbes to the host
Abubakar
they provide healthier benefits to their hosts
ayesha
They are friends to host only when Host immune system is strong and become enemies when the host immune system is weakened . very bad relationship!
Mark
what is cell
faisal Reply
cell is the smallest unit of life
Fauziya
cell is the smallest unit of life
Akanni
ok
Innocent
cell is the structural and functional unit of life
Hasan
is the fundamental units of Life
Musa
what are emergency diseases
Micheal Reply
There are nothing like emergency disease but there are some common medical emergency which can occur simultaneously like Bleeding,heart attack,Breathing difficulties,severe pain heart stock.Hope you will get my point .Have a nice day ❣️
_Adnan
define infection ,prevention and control
Innocent
I think infection prevention and control is the avoidance of all things we do that gives out break of infections and promotion of health practices that promote life
Lubega
Heyy Lubega hussein where are u from?
_Adnan
en français
Adama
which site have a normal flora
ESTHER Reply
Many sites of the body have it Skin Nasal cavity Oral cavity Gastro intestinal tract
Safaa
skin
Asiina
skin,Oral,Nasal,GIt
Sadik
How can Commensal can Bacteria change into pathogen?
Sadik
How can Commensal Bacteria change into pathogen?
Sadik
all
Tesfaye
by fussion
Asiina
what are the advantages of normal Flora to the host
Micheal
what are the ways of control and prevention of nosocomial infection in the hospital
Micheal
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Source:  OpenStax, General chemistry ii. OpenStax CNX. Mar 25, 2005 Download for free at http://cnx.org/content/col10262/1.2
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