Heats of Reaction

Heat of Reaction

The Heat of Reaction experiment will also be carried out using a temperature probe connected to a computer. The data collection will be carried out using the calorimetry experiment in LoggerPro®.
There is a tutorial on the use of........................................... LoggerPro

The experiment will involve one of the following reactions....

...
HCl + NaOH -------> NaCl + H₂O
HOAc + NaOH -------> NaOAc + H₂O

Use this equation to determine the limiting reagent.

The computer program, , will assign you volumes of NaOH, HCl or HOAc and water to use. HOAc is acetic acid, HC₂H₃O₂.
Using a 10 mL graduated cylinder, add to your calorimeter, the assigned volume of NaOH and wash it in with the assigned volume of water. Add a magnetic stirring bar.
Add the assigned amount of ACID to your graduated cylinder. Go to a computer and insert the temperature probe
Start the Calorimetry experiment in DATALOGGER.
The first 20 sec are used to establish the initial temperature. Then add the ACID from the graduated cylinder. There will be a sudden change in temperature which will stabilize at a new level. The experiment stops automatically at 120 sec.
Analyze the DATA to establish the initial and final temperatures.
Identify with a title and personalize with your name the graph. Print out a copy for your report.

SOME CAUTIONS:
Make sure you use 6.00 M reagents, not 6 M reagents.

CALCULATIONS

MOLAR HEAT of REACTION is defined as...... kilojoules of energy absorbed when one mole of reactant reacts.
If energy is given off by the reaction, the temperature of the system rises. The reaction is exothermic and the HEAT OF REACTION is negative(-)

The following Assumptions are made to simplify the calculations:

Calorimeter Constant is 0.00 j/ºC
All liquids added act exactly like water.
The density of the liquids is 1.00 g/mL

EQUATIONS

(Volume in mL)(Molarity) = millimoles

Volume_HCl+ Volume_NaOH+ Volume_water = Volume_liquids

Temperature_final-Temperature_initial = Temp. Change_liquids

(Mass_liquids)(-Temp. Change_liquids)(4.18 j/gºC) = Energy Change

Energy Change/[(1000 j/Kj)(Moles of Limiting Reagent)] = DH Reaction

Always make the following checks of your calculations.....

If the temperature went up...	Heat of Reaction is negative (-)
If the temperature went down...	Heat of Reaction is positive (+)