0.12 Thermochemistry  (Page 2/3)

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The enthalpy of a reaction might be difficult to obtain directly by experiment but can be determined by measuring (or looking up in tables) the enthalpy changes of reactions which contain the reactants and products in a process governed by Hess's Law of Heat Summation. In Part II of this experiment you are asked to find the enthalpy of hydration of ${\text{CaCl}}_{2}\left(s\right)$ the "target reaction" in this manner.

Target reaction:  ${\text{CaCl}}_{2}+{6H}_{2}O={\text{CaCl}}_{2}\cdot {6H}_{2}O$

It cannot be measured directly because of the slow kinetics of the reaction in the solid state. However, the heats of dissolution of ${\text{CaCl}}_{2}$ and ${\text{CaCl}}_{2}\cdot {6H}_{2}O$ can be determined and, using Hess's Law, the enthalpy of hydration can be calculated.

Theoretical value of the enthalpy of hydration of ${\text{CaCl}}_{2}$ anhydrous is -81.33kJ/mol. Theoretical value of the enthalpy of hydration of ${\text{CaCl}}_{2}\cdot {6H}_{2}O$ is 15.79 kJ/mol.

Materials required

• two Styrofoam cups (serve as the calorimeter)
• styrofoam cover (top to the calorimeter)
• conventional or digital thermometer
• stirring motor and stir bar
• two large Ziploc bag
• two plastic spoons

Setup of the microlab thermistor

• Open the MicroLab Program by clicking on the Shortcut to MicroLab.exe tab on the desktop.
• On the“Choose an Experiment Type”Tab, enter a name for the experiment, and then double click on the MicroLab Experiment icon
• Click“Add Sensor”, Choose sensor = Temperature (thermistor)
• Choose an input, click on the red box that corresponds to the port that your thermistor is connected to.
• Label = Thermistor, sensor units = $°C$ , click next
• Click“Perform New Calibration”
• Click“Add Calibration Point”place the thermistor and thermometer in an ice water bath. Wait until the temperature is constant and then read the temperature on the thermometer (to the nearest 0.1 $°C$ ) and enter it into the“Actual Value”box in MicroLab and hit“ok”.
• Again, Click“Add Calibration Point”place the thermistor and thermometer in warm water bath. Wait until the temperature is constant and then read the temperature on the thermometer (to the nearest 0.1 $°C$ ) and enter it into the“Actual Value”box in MicroLab and hit“ok”.
• Under Curve Fit Choices , click on“First order (linear)”and then“Accept and Save this Calibration”, when prompted to enter units, set as deg C. Save as your name-experiment-date.
• Click“Add Sensor”, Choose sensor = Time
• Choose an input, click on the red box that corresponds any of the Timers.
• Label = Time 1, click next, click Finish.
• Left click on thermistor and drag to the Y-axis over“data source two”, also click and drag to column B on the spreadsheet and also click and drag to the digital display window.
• Left click on Time and drag to the X-axis over“data source one”, also click and drag to column A on the spreadsheet and also click and drag to the digital display window.
• When you are ready to obtain data, click start. When you are finished collecting data, click stop. To run another trial, click repeat experiment.

Part i. reaction of strong acid with strong base

• Weigh the calorimeter (styrofoam cups with lid) WITH a stir bar. Accurately measure 50 mL of 1 M HCl into your calorimeter. Turn on the stirring motor to the medium speed. Fit the thermistor though the cardboard lid to a length such that its tip goes deep into the solution but misses the stir bar. Cover the calorimeter.
• Start the Acquisition program. You should see successive, constant temperature readings of near room temperature. Accurately measure 50 mL of 1 M NaOH and quickly add it to the acid solution in the Styrofoam cups. Cover the calorimeter.
• Continue monitoring the temperature change until thermal equilibrium is reached (the temperature stops changing or starts decreasing).
• Stop the Acquisition program. SAVE YOUR FILE. Remove the cardboard lid, reweigh the calorimeter and record the information on your lab report.
• Repeat the same procedure (Steps 1-4) two more times. Save all your files. Give them different, distinguishable names.

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
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Renato
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Stoney Reply
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Adin Reply
?
Kyle
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Adin
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Adin
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Kyle
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Joe
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Damian Reply
research.net
kanaga
sciencedirect big data base
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Introduction about quantum dots in nanotechnology
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nano basically means 10^(-9). nanometer is a unit to measure length.
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there is no specific books for beginners but there is book called principle of nanotechnology
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Devang Reply
are you nano engineer ?
s.
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.
Tarell
what is the actual application of fullerenes nowadays?
Damian
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.
Tarell
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.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
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.
Harper
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s.
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for screen printed electrodes ?
SUYASH
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s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
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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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