Exam (elaborations)
Undertake calorimetry to study cooling curves
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This coursework is showing my practical findings about calorimetry.
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Calorimetry (Heating and Cooling)Aim:Calorimetry measures enthalpy changes during chemical
processes, where the magnitude of the temperature change depends on
the amount of heat released or absorbed and on the heat capacity of the
system.
The aim of the experiments is to determine physical changes and
temperature change and study cooling curves of both stearic acid and
salol wax.
Heating and Cooling Curve equipment:
● Eye protection
● Beaker (250 cm3)
● Boiling tube
● Thermometer (0–100˚C)
● Stop clock
● Clamp, stand and boss
● Bunsen burner
● Tripod
● Gauze
● Heat resistant mat
Method:
1. Put about 150 cm3 water into the beaker.
2. Heat it on a tripod and gauze until the water just starts to boil.
3. Set up the apparatus as shown in the diagram and start the timer.
Keep the water boiling, but not boiling vigorously.
4. Using a suitable results table, record the temperature of the stearic
acid every minute until it reaches about 70˚C. Note on your results
table the point at which you see the solid start to melt.
5. Use the clamp stand to lift the tube from the hot water. Record the
temperature every minute as the stearic acid cools down until it
reaches about 50˚C. Note on your results table the temperature at
which you see the stearic acid begin to solidify.
, Less than 5g of stearic acid I used means the thermometer is not fully
submerged into the mixture, which makes it less accurate.
How can you ensure accuracy?
● Collect as multiple measurements of the needed material.
● Find the average value of your measurements.
● Reliability can be improved by carefully controlling all variables.
Calibrating thermometer: Add to water bath and boil till it gets to 100C
and immediately add to cold water bath.
Equipment/ Risk Prevention Treatment
Chemical hazard
Boiling water Burns Wear correct lab Wash the burned
coat and goggles area with plenty
of cold water and
seek medical
help if the case is
very serious.
Bunsen burner Burns Wear lab coat Seek medical
help and wash
the burned area
with plenty of
cold water.
Glassware Cut and bleeding Wear lab coat Get the first aid
kit and put a
plaster on the
cut.
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