Experiment
1.1
Working in the Chemistry Laboratory (4)
Report=163
Introduction: (5)
One of the most important components of your
chemistry course is the laboratory experience.
Although you may have performed experiments
in other science courses and may be familiar
with some of the laboratory equipment, there is,
nevertheless, a great deal more to be learned
about the equipment and the safety procedures
that are used in a chemistry laboratory.
A number of important procedures need to be
mastered in order for you to perform the
experiments in this course successfully. You will
need to know how to use a Tirrill burner, how to
filter liquids, how to handle solid chemicals and
solutions, and how to heat materials safely. It is
important to learn how to make accurate
measurements by using graduated cylinders,
thermometers, and balances. In addition, you
need to learn how to take necessary precautions
so that you can work safely in the laboratory.
In this introductory experiment, you will have a
chance to learn these laboratory techniques as
you perform an experiment involving a water
solution of calcium hydroxide, Ca(OH)2,
commonly called limewater. Limewater is used
in a test for the presence of carbon dioxide, CO2,
an important product of animal respiration.
When carbon dioxide is bubbled through
limewater, a cloudy appearance is noted. This
cloudiness will eventually settle out and is called
a precipitate.
Objectives: (2)
1. Demonstrate mastery of essential
laboratory techniques and procedures
as well as a familiarity with laboratory
equipment.
2. Apply laboratory precautions to
laboratory procedures.
3. Observe the reaction between limewater
and carbon dioxide.
4. Interpret the results of two chemical
reactions.
5.
Use LoggerPro to determine pH and
temperature.
Materials: (5)
Apparatus:
safety glasses
laboratory apron
Tirrill burner
centigram balance
filter paper
stirring rod
6-mm bent glass tubing
125 mL Erlenmeyer flask
50 mL Erlenmeyer flask
one hole stopper
ring stand
utility clamp
Logger Pro thermometer
Logger Pro pH
spark lighter
250 mL graduated cylinder
glycerine
hot plate
2-250mL beakers
Reagents:
1.0 M HCl, hydrochloric acid
magnesium ribbon
sodium carbonate
calcium hydroxide
deionized water
Procedure:
Part 1
1. Adorn your safety glasses and lab apron.
2. Observe your gas burner. It is a modification
of the Bunsen burner, called a Tirrill burner.
There is an inlet for the gas, an adjustment for
the flow of gas, and an adjustment for the flow of
air. A proper mix of air and gas will yield a faint
blue flame for maximum heat and minimum
Experiment 1-1
soot. Identify the air adjustment and the gas
adjustment on your burner. Before lighting the
burner, turn the air adjustment to allow as little
air as possible.
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slide the tubing gently through the hole of the
one hole stopper.
9. Get stamp #2.
Part 3 (Make solution and filter)
10. In order to make the limewater solution, you
must be able to use a lab balance. A balance
must be zeroed before it is used to find masses.
The balance is on a flat, stable surface. Find the
zero-adjusting button. Press it.
11. Chemicals are measured in a container or
on paper, never directly on the pan or platform
of a balance. Place a clean, dry weigh boat on
the pan of the balance. Press the tare button.
3. Before you light the burner, check to make
sure that all students nearby are wearing their
safety goggles. Lighting the burner is a one
person job. Have a match or spark
lighter(striker) ready before you turn on the gas.
Light the burner by turning on the gas and
holding the spark lighter or lighted match above
the barrel of the burner.
4. Adjust the flame to a blue color by changing
the flow of air and the flow of gas. If the flame
flutters and roars, you have added too much air
or not enough gas.
12. Place approximately 1 g of calcium
hydroxide in the weigh boat and find it’s mass to
the nearest 0.01 g. Record this mass on the
Report sheet.
13. Get stamp #3 for massing calcium
hydroxide.
14. Add the calcium hydroxide to a clean, dry
250 mL beaker. Use your deionized water bottle
to remove all solid from weight boat by
squeezing the corners of weight boat together
and using the wash bottle to wet the solid and let
gravity do its thing so that the solid leaves the
weigh boat into the beaker.
15. Use a 250 mL graduated cylinder to
measure exactly 175 mL of deionized water
16. Get stamp #4 for graduated cylinder
17. Add the water to the calcium hydroxide in
the beaker.
5. Get your first stamp by showing your properly
operating burner.
6. Turn off the burner and go on to the next part
of the experiment
18. Stir the solution with a stirring rod. Calcium
hydroxide is difficult to dissolve. Heating the
solution will speed the process. Set the beaker
on a hot plate, turn it to “high”, and heat the
solution, stirring occasionally (**See Note**), for
approximately 5 minutes. Do NOT boil! Not all
of the solid will have dissolved, even after
heating. Turn off the hot plate. Remove the
beaker from the hot plate and place it on the
ceramic tile. Let the solution cool and settle for
at least five minutes while you set up a funnel to
filter the solution.
Note: When using a stirring rod, best way to
keep uncontaminated is to place it in a small
beaker with dionized water.
Part 2
7. Obtain a piece of glass tubing that is at 90
degree bend.
8. Find a stopper that has one hole and fits a
125-mL Erlenmeyer flask. Using a drop of
glycerine to lubricate the hole in the stopper,
Experiment 1-1
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As shown below
19. The filtration apparatus is shown below.
20. Turn on the vacuum pump. The filter paper
should “suck” onto the funnel and make a
whistle sound and you can see all the holes
through the filter paper. As shown below:
Obtain a filter paper from the chemical shelf.
Go to a filtration system set-up at different areas
around the lab. Make sure rubber stopper is in
the Hirsch funnel
Place Hirsch funnel into a side arm flask. Make
sure the flask is securely fastened to a utility
clamp and ring stand. Put rubber hose into the
side arm of the flask.
Place filter paper into the Hirsch funnel. Make
sure all the holes in the funnel are covered up by
the filter paper. As shown below:
Pour the solution supernate down your stirring
rod into the filter paper.
Take your deionized water bottle to wet down
the filter paper. Make sure all filter paper is wet.
Allow the clear solution to filter into the beaker
below. Be careful to get the solid on to the filter
paper and not on the sides. You do not have to
filter the whole solution just enough to get 150
mL. You will use the clear limewater for Parts 4,
5, and 6. Put the filter paper and any solid it
may contain into garbage. Wash all other
glassware thoroughly with soap and water.
Place the clear limewater into a clean 250 mL
beaker.
Experiment 1-1
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21. Get stamp #5.
Part 4 (Measure pH)
pH is a common measurement of solutions.
pH measures how acidic a solution is (how
much hydrogen ions present). Low pH =
many H ions. High pH = low H ions.
in and out the pipette. Use a 250 mL beaker to
place the DI water.
30. Get Stamp #7.
31. Add the 20 mL of clear limewater into a 50mL Erlenmeyer flask.
32. Obtain a soda straw and gently blow into the
limewater through the soda straw. Continue to
exhale into the tube until you observe a change.
Record your observations on the Report Sheet.
33. Get stamp #8.
22. We will be using LoggerPro sensors to
measure pH. Make the pH sensor (see picture)
is attached to sensor port.
Part 6
34. Rinse the 50 mL flask you used in Part 5 and
fill it with 20 mL of fresh, clear limewater as
before.
35. In a 125 mL Erlenmeyer flask, place 25 mL
of 1M hydrochloric acid.
36. Measure the pH of your acid in the flask and
record.
Another use of LoggerPro is to measure
temperature.
37. Re-open Logger Pro if you closed it
23. Double click on LoggerPro icon on desktop
of computer.
24. Both pH and temperature boxes should
show up on bottom left.
25. To remove the sensor from its container, just
unscrew the cap. DO NOT pull the sensor out
from the cap.
26. Clean the sensor by washing it with DI water
from squeeze bottle.
27. Place sensor into your 250 mL beacker of
clear limewater and wait for the sensor to stop
fluctuating. Record pH
28. Clean the pH sensor by swirling the sensor
in a 250 mL beaker full of DI water. Then rinse
the sensor with DI squeeze bottle.
29. Screw the cap back on and place it back in
its upright position.
30. Get stamp #6.
Part 5
31. Measure out 20 mL of the clear limewater
into the appropriate graduated cylinder. Use a
pipette to get exactly 20 mL. Make sure you
clean your pipette by squeezing fresh DI water
Experiment 1-1
38. Using a thermometer, measure the
temperature of the acid and record it on the
Report Sheet. Rinse the end of the
thermometer with water after removing it from
the acid.
39. Obtain your bent tubing from part 2. Obtain a
piece of magnesium ribbon approx 5 cm long.
Carefully drop the magnesium into the acid and
quickly place the stopper with the bent tubing on
the top of the flask. Place the open end of the
tubing below the surface of the limewater in the
50 mL Flask. Observe what happens and
record your observations on the Report Sheet.
40. As soon as the reaction stops, remove the
stopper and measure the temperature and pH of
the acid. Record it on the Report Sheet.
41. To dispose of ANY excess acid, place about
a tablespoon of baking soda to neutralize the
acid. Pour out the neutralized acid and place
any unreacted magnesium into the trash. Pour
the limewater down the drain. Rinse out the
glassware.
42. Repeat the same experiment but with no
limewater. You will be testing the gas with a fiery
splint.
43. Set-up your Tirrell burner. Obtain a wood
splint. Obtain the correct amount of magnesium
as before. Add the correct about of HCl to the 50
mL Erlenmeyer flask.
44. Light your burner. Set your splint on fire and
turn off burner.
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45. Quickly add your magnesium and let react
for about 10 seconds. Place splint over the
mouth of the flask and record your observations.
50. Dispose your acid as before. Rinse out the
glassware.
51. Repeat the same experiment but with no
limewater. You will be testing the gas with a fiery
splint.
46. Dispose your acid and magnesium as
before. Throw splint into the trash. Rinse out the
glassware.
52. Set-up your Tirrell burner. Obtain a wood
splint. Obtain the correct amount of sodium
carbonate as before. Add the correct about of
HCl to the 50 mL Erlenmeyer flask.
47. Place 20 mL of limewater in the 50 mL Flask
as done before
48. Place 35 mL of 1 M HCl in the 125 mL flask.
Obtain ≈2 grams of sodium carbonate. Carefully
transfer the sodium carbonate into the 125 mL
flask and quickly place the stopper with the bent
tubing on the top of the flask. Place the open
end of the tubing below the surface of the
limewater in the 50 mL Flask. Observe what
happens and record your observations on the
Report Sheet.
53. Light your burner. Set your splint on fire and
turn off burner.
54. Quickly add your solid and place splint into
the mouth of the flask and record your
observations.
55. Dispose your acid as before. Throw splint
into the trash. Rinse out the glassware, followed
by rinsing 3 times with 10 mL of deionized water.
49. As soon as the reaction stops, remove the
stopper and measure the temperature and pH of
the acid. Record it on the Report Sheet.
56. Get stamp #9.
57. Before leaving the laboratory, clean up all
materials and wash your hands
Data and Observations: (108)
Part 1
(10) Stamp 1.........................
Part 2
(10) Stamp 2.........................
Part 3
(2) mass of calcium hydroxide
g
(10) Stamp 3.........................
(10) Stamp 4.........................
(10) Stamp 5.........................
Part 4
(2) pH of limewater
(10) Stamp 6.........................
Part 5
(10) Stamp 7.........................
Observations of blowing into limewater.
(10) Stamp 8.........................
Experiment 1-1
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Part 6
(14) Data:
HCl / Mg Reaction
HCl / Na2CO3 Reaction
pH of Acid before reaction
Temperature before reaction
Temperature after reaction
pH after reaction
Reaction description
Limewater description
Splint Test
(10) Stamp 9.........................
Analysis and Conclusions: (23)
(6) 1. In part 6, was carbon dioxide produced in
either of the reactions? How do you know?
(6) 2. In part 6, was hydrogen gas produced in
either of the reactions? How do you know?
(3) 3. What three observations in part 6 lead you to
believe that chemical reactions occurred?
(2) 5. Why was it necessary to filter the cloudy
limewater prior to use in parts 4, 5, and 6?
(2) 6. Why is it necessary to use a weigh boat or
some other container when you find the mass
of solids? (two reasons)
(2) 7. Based on the pH, is limewater acidic or basic?
(2) 4. Why was the limewater solution you made in
part 3 cloudy?
Synthesis: (16)
(2) 1a. If you were to find the mass of the
hydrochloric acid and the mass of the
magnesium strip before the reaction, how
would that mass compare with the mass of
the material remaining in the flask after the
reaction was complete?
(2) 4. Many antacids are carbonate or bicarbonate
compounds. One manufacturer used to refer to
the “burp of relief” when a person took the
antacid. Explain what is meant by “burp of
relief” and what is reacting with the antacid.
(2) 1b. If you were able to contain the gas produced
(rather than let it escape as you did), how
would that procedure affect the masses
before and after the reaction?
(4) 2. A number of SI units were used in this
experiment. Review the procedure and make
a list of all of the units you used in your
measurements.
(6) 3. Matter in three different phases was observed
in this experiment. Give two examples from
the experiment of each phase.
solid: ______________________
liquid: ______________________
gas: _______________________
Experiment 1.1
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