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One of the most important principles from Physics is the Conservation of Energy. This tells us that energy is neither created nor destroyed in any process, including a chemical process. Rather, energy is converted from one form to another during these processes. The energy conversion might possibly be from more useful forms to less useful forms of energy, but the energy is nevertheless conserved.

We will assume a foundation in the different types and energies of chemical bonds. In particular, we must recall that atoms are bonded together when their energy when bonded is lower than their energy when separated. Therefore, breaking a chemical bond requires the input of energy to do work on the bonded atoms by separating them. The more energy required, the stronger the bond.

Observation 1: temperature changes during chemical reactions

Since we are interested in the energy changes which happen during chemical reactions, it makes sense to look at reactions which have the most conspicuous energy changes, those which evolve heat. “Fire” is probably the first known human-controlled chemical reaction. Burning is now understood as a combustion reaction of oxygen with a fuel, such as wood, oil, or natural gas. These reactions were all originally carried out primarily as sources of heat for warmth or cooking. In common terms, we use combustion of fuel to “heat up,” that is, to make something hotter or, better said, to raise the temperature of something.

It is pretty easy to observe that whatever is released during a chemical reaction which makes things hotter is a form of energy. For example, we can carry out the combustion reaction in a closed space that can expand, such as inside a cylinder with a piston inserted to close off the contents of the reaction. As the reaction occurs, we observe that the piston is pushed back, so work is done on the piston, meaning that the reaction has released energy to do that work. (This is the principal mechanism behind an internal combustion engine, of course.) When this transfer of energy creates temperature changes, we call this transfer “heat.”

Since heat can be defined in terms of temperature changes, this tells us that temperature and heat are very closely related concepts. We need a means to measure temperature. It is not enough for us to simply say that something hot has a high temperature. We need a measurement scale that allows us to compare “how hot” objects are compared to each other. There are lots of ways to do this. All of them are based on measuring some property which correlates to “hotness.” We most commonly use the expansion and contraction of liquid mercury in a glass tube, but we can observe expansion and contraction of solid metals, gases, etc. Or, we can observe other properties that vary with “hotness,” like the variation of resistance in wires or thermocouples or like the spectrum of infrared light emitted by a substance. This is why there are so many types of thermometers. As long as they are calibrated against each other so that they give the same reading when the temperature of a specific object is measured, all of them are useful.

Questions & Answers

What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Concept development studies in chemistry 2013. OpenStax CNX. Oct 07, 2013 Download for free at http://legacy.cnx.org/content/col11579/1.1
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