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Thermochemistry

We will begin lab in the amphitheatre of DBH

Objective

  • To explore heat transfer through calorimetry.
  • To use calorimetry to determine the enthalpy of reaction of a strong acid and a strong base.
  • To use Hess's Law of Heat Summation to determine the heat of hydration in calcium chloride.
  • To explore a common use of heat of reaction in real life.

Grading

  • Pre-Lab (10%)
  • Lab Report Form (80%)
  • TA Points (10%)

Background information

When two objects at different temperatures are brought into physical contact, thermal energy will spontaneously transfer from the warmer object to the colder object until both objects have achieved the same temperature. Assuming the two objects are thermally insulated from their surroundings, the heat lost by the warm object is identical to the heat gained by the cold object. This is a manifestation of the Law of Conservation of Energy.

The heat transfer, q, is a function of the mass of the object (m), the change in temperature undergone by the object ( ΔT size 12{ΔT} {} ) and the object's specific heat ( C s size 12{C rSub { size 8{s} } } {} ). This statement can be expressed mathematically as

q = mC s ΔT size 12{ ital "mC" rSub { size 8{s} }ΔT} {}

Temperature change is always defined as T final size 12{T rSub { size 8{ ital "final"} } } {} - T initial size 12{T rSub { size 8{ ital "initial"} } } {} , which means that q for the hotter object ( q hot size 12{q rSub { size 8{ ital "hot"} } } {} ) is negative and q for the colder object ( q cold size 12{q rSub { size 8{ ital "cold"} } } {} ) is positive. If energy is conserved, then

q hot size 12{q rSub { size 8{ ital "hot"} } } {} + q cold size 12{q rSub { size 8{ ital "cold"} } } {} = 0

and

( mC s ΔT size 12{ ital "mC" rSub { size 8{s} }ΔT} {} ) hot size 12{ {} rSub { size 8{ ital "hot"} } } {} + ( mC s ΔT size 12{ ital "mC" rSub { size 8{s} }ΔT} {} ) cold size 12{ {} rSub { size 8{ ital "cold"} } } {} = 0

Now consider dropping an ice cube into water just warm enough to melt the ice cube but not warm enough to further heat the water from the cube. The observation is that the ice cube melts and the warm water cools to 0 ° size 12{0°} {} C. It is important to recognize that during the phase change, the temperature of the ice cube does not change. Therefore, it is not possible to use the preceding equation to determine the heat transferred. Rather, the energy transferred to the ice cube from the warm water affects the phase change. The energy equation is now adjusted to incorporate the enthalpy required to melt the ice cube, ΔH f size 12{ΔH rSub { size 8{f} } } {} (where f stands for fusion):

( mC s ΔT size 12{ ital "mC" rSub { size 8{s} }ΔT} {} ) warm size 12{ {} rSub { size 8{ ital "warm"} } } {} + ΔH f size 12{ΔH rSub { size 8{f} } } {} = 0

It is also possible to have thermal energy when chemical reactions occur. The amount and direction of heat flow is dependant on the chemicals reacting. Using a calorimeter, it is possible to experimentally determine the heat of reaction.

Calorimetry

In the technique known as constant-pressure calorimetry, enthalpies of phase changes or chemical reactions are determined indirectly by measuring temperature (at constant pressure) changes in a medium, most often water, surrounding the materials undergoing the change. That is, by measuring ΔT size 12{ΔT} {} of the water one can use the preceding equation to calculate ΔH size 12{ΔH} {} for the process of interest. Of course, this means one must know the mass of the water used and water's specific heat: C water size 12{C rSub { size 8{ ital "water"} } } {} = 4.18 J/(gK).

Today in Part I, you will add a strong base to a strong acid, measure the temperature change in the water as the two react, and use that information to calculate the heat of reaction per gram of NaOH. Then convert your experimental value into an enthalpy in kJ/mol (of NaOH).

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
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
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Gen chem lab. OpenStax CNX. Oct 12, 2009 Download for free at http://cnx.org/content/col10452/1.51
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