EXPERIMENT 3:
TEMPERATURE
Introduction: You will learn to work with the Bunsen burner and take temperature
measurements with a thermometer. You will apply the graphing principles you have learned to
graph a cooling curve as a beaker of hot water loses heat over a period of time.
Materials:
250 mL beaker, thermometer, ring stand, iron ring, wire gauze,
thermometer holder (obtain from stockroom), Bunsen burner, 2 boiling stones
An exercise with the burner and thermometer.
Part 1:
The "Bunsen" burner is commonly used for laboratory heating operations. There are
several types of burners, differing in details of construction, but each has a gas inlet that attaches
to a valve on the bench, a gas regulation knob, a tube for mixing air and gas, and an opening near
the base of the tube for introduction of air. Find these parts on your burner and make a neat,
labeled sketch of the burner on your report sheet.
Light the burner by partially closing the air vent and slightly opening the gas regulation
knob, turning on the bench gas valve, and bringing a match in toward the top of the burner from
the side, touching the top of the tube. Observe the flickering orange flame. This kind of flame is
called a “luminous flame”. Open the air hole about half way and open the gas regulation knob
until the flame is about 8 to 10 cm high and the flame is blue. A blue flame is hotter than an
orange flame. Once again close the air hole at the base of the tube. Using crucible tongs, hold an
evaporating dish about 5 cm above the top of the tube. Observe what happens on the dish.
Part 2:
In this part of the experiment you will work alone. Each student must check out a
thermometer, a thermometer holder, and a stopwatch from the stockroom or from your instructor.
Set up a ring stand with an iron ring and wire gauze. Weigh a 250 mL beaker with two boiling
stones. Measure out approximately 150 to 175 mL of deionized water in a graduated cylinder
then add it to the beaker. Re-weigh the beaker with water. Record all of your data on the report
sheet. Calculate the weight of water. Place the beaker of water on the wire gauze and set up the
Bunsen burner next to the ring stand. Measure the temperature of the water to the nearest 0.1oC
(this is room temperature).
note – you may check out a thermometer holder
to use instead of the utility clamp shown
Position the thermometer in the water and heat the water
boiling. Do not allow the thermometer to touch the sides
bottom of the beaker. Keep the thermometer suspended.
Practice adjusting the flame, by making it yellow, then
blue, then blue with a sharp blue cone inside the lighter
flame.
to
or
faintly
blue
Theory states that water boils at a constant temperature until all of the liquid is converted into its
gaseous state. You will test this statement by measuring the temperature of boiling water for 15
minutes in 5 minute intervals. Allow the water to boil for 5 minutes and while the flame is still
active, measure the temperature of the water then repeat this measurement after another 5
minutes. Look up the boiling point of water and compare that value to your experimentally
determined value. This technique is referred to as “calibration of the thermometer”. Is your
thermometer accurate? Record the temperature of boiling water again 5 minutes later. Has it
changed? The boiling point of any pure substance is characteristic of that material and can be
used to identify that substance. Record your observations
Part 3:
Turn off the burner. Clamp the thermometer to the ring stand and submerge the tip of the
thermometer in the cooling water. When the water has reached about 85oC, start recording the
temperature at 1minute intervals. Use a glass rod to gently stir the water. Use the stopwatch to
keep track of time. Record the temperatures to the nearest 0.1oC. Continue making
measurements for 30 minutes or until the temperature reaches 35oC. Graph this data, either by
hand or by using Excel, as temperature vs. elapsed time to create a cooling curve. Record time
in minutes on the x-axis and temperature in oC on the y-axis. Draw a smooth curve passing
through most of the points. Attach the graph to the report sheet. Do not forget to title the graph.
Part 4:
Once the water has returned to room temperature, record the temperature again. It must match
the first temperature reading before you heated the beaker of water. Weigh the beaker of water.
Calculate the amount of water missing.
Part 5:
Use the Fahrenheit – Celsius conversion formulas to set up a table of several sets of temperatures
in oF and oC ranging from –50oC up to 100oC.
o
F = 1.8 oC + 32
C = oF – 32
1.8
o
Your instructor will require you to graph the values in the table provided using either Excel or by
hand. Use the x-axis for the Celsius degrees and the y-axis for the Fahrenheit degrees.
Find the slope of the graph.
Attach both graphs to the report sheets along with any notebook copy pages
EXPERIMENT 3: Report Sheet
A STUDY OF TEMPERATURE:
Name: ______________________
section ________________
Part 1: Observations
Sketch of burner (Label parts):
1. What color is the flame when the oxygen intake has been minimized? ____________
2. What color is the hottest flame?
________________________
3. What deposits on the bottom of the evaporating dish when a luminous yellow flame
applied to the dish? _________________
4. What do you think is the cause of the deposit on the evaporating dish?
5. (Optional question): Write a chemical equation describing this event (combustion).
Part 2: Data
Weight of beaker and water
__________________
Weight of beaker
__________________
Weight of water
__________________
Room Temperature of water
__________________
Calibration of the thermometer:
Temperature of boiling water (1st)
__________________
Temperature of boiling water (2nd)
__________________
Temperature of boiling water (3rd)
__________________
1. What is the theoretical temperature of boiling water from handbook? _________
2. Is your thermometer accurate?
___________
is
Part 3: Data for cooling water
Elapsed Time in minutes
Temperature (oC)
Part 4: Data and observations
Temperature of water before heating
__________________
Weight of beaker and water once cooled
__________________
How much water was lost during the boiling process? __________________
Explain what happened to the water that was lost.
Part 5: Temperature conversions
Fill in the table below with some temperatures in Celsius and their equivalent values in
Fahrenheit degrees.
Celsius
Fahrenheit
– 50.
0.
75
100.
Plot the Celsius degrees on the x-axis and the Fahrenheit degrees on the y-axis. Pick two points
on the graph that are fairly far apart to calculate the slope. Do not use the points which you have
already plotted. Find 2 new points arbitrarily, on the line. Show set-up of slope calculation or
how it was obtained from the computer-generated equation of the line.
Comment on the value you obtained for the slope of the graph.
At what temperature is the Celsius reading the same as the Fahrenheit? ________
(Show Calculations)