Intro to Chemistry Chem1020 Lab
Separation of Mixtures
Chemistry Department
Minneapolis Community & Technical College
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Overview
• Part I
Schematic demonstration of the overall procedure
• Part II
Mass measurement
• Part III
Physical method: sublimation
• Part IV
Physical method: filtration
• Part V
Calculation
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Part I. Procedure
In this experiment, you will be given a
solid mixture that contains three
substances. They are ammonium chloride,
sodium chloride, and sand. Your goal is to
separate the mixture into these three
substances, then determine the mass and
composition percentage of each substance.
Two physical methods, sublimation and
filtration, will be used to separate the
components.
Make sure to record
this unknown number
on your data sheet.
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8. Weigh the paper and
the sand after drying
(Mpaper+sand).
1. Weigh the empty
evaporating dish (Mdish)
2. Add solid mixture
7. Add water which dissolves
sodium chloride only. Filter
out the sodium chloride and
water with filter paper. Only
sand will be left on the paper.
4. Heat the dish.
Ammonium chloride
6. Weigh a piece
sublimes into gas
5. Weigh the dish with just of filter paper
3. Weigh the dish with the and escapes.
sodium chloride and sand left (Mpaper).
mixture (Mdish+mixture)
(Mdish+mixture after heating)
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Part II. Mass Measurement
1. Always use the same balance during
one experiment and record the
weighing
balance number.
paper
balance
number
2. Always have a piece of weighing
paper on the balance.
3. Before putting your object on the
balance, press the “Zero” or “Tare”
button to zero it.
“zero”
button
A top-loading balance
4. Carefully put the object on the balance,
and record all digits shown in the display
(including zeros) with the unit of “g”.
Example: this evaporating dish is 36.66 g.
5. Avoid spilling. If it ever happens, alert the
instructor.
6. Never put a hot object on the balance!
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Part III. Sublimation
Since the gaseous ammonium chloride is hazardous when
inhaled, perform this procedure in the fume hood!!!
• Heat the mixture in the dish with a
Bunsen burner. Review the next slide for
how to light up the burner.
• Stop heating when there is no more white
fume forming (what substance is it?) and
no yellow color left in the solid mixture.
• Carry the hot evaporating dish back to
your station with a beaker.
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How to Light up a Bunsen Burner? An Important Skill in a Chem Lab
1. Connect the burner and the gas
valve with a rubber hose.
2. Gently close the gas valve
of the burner.
5. Approach a lit
stick or a striker to
the top of the
barrel.
4. Turn to open the
gas valve.
Meanwhile quickly
turn on the gas
valve of the burner.
A striker
3. Gently close the air valve
of the burner.
Hottest spot
6. Turn on
the air valve
until you see
two blue
cones formed
in the flame.
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Part IV. Filtration
Folding the filter paper
John D.
Funnel
Clay triangle
1. Weigh and label
1. Open the paper cone with 3
layers on one side and one
layer on the other side.
John D.
2. Fold into halves with
name facing inside
Filtration apparatus
2. Wet the paper with water.
3. Fold into halves again
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3. Pour the sand, sodium chloride, water
mixture into the filter paper cone. Rinse
the evaporating dish with distilled water to
transfer all of the solid.
4. Wash the solid remaining on the
paper with more water to remove
residual sodium chloride.
John D.
5. What is remaining on the paper now? Remove
the paper and open it up onto a watch glass. Dry
in the oven.
John D.
6. Weigh the dried sand
with the filter paper.
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Part V. Sample Calculation
Data:
Mevaporating dish
36.66 g
Mdish+mixture
39.06 g
Mdish+mixture (after heating)
38.05 g
Mfilter paper
0.82 g
Mpaper+sand
1.24 g
For some reasons that will be explained later in the semester, when you do
subtraction in this calculation, always keep two decimal places. However
it is more complicated with dividing. To make it simpler, always keep one
decimal place in this calculation.
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Calculation:
Mmixture = Mdish+mixture - Mevaporating dish
=39.06 g – 36.66 g = 2.40 g
Mammonium chloride = Mdish+mixture - Mdish+mixture (after heating)
=39.06 g – 38.05 g = 1.01 g
Msand = Mpaper+sand - Mpaper
=1.24 g – 0.82 g = 0.42 g
Msodium chloride = Mmixture - Mammonium chloride - Msand
=2.40 g – 1.01 g – 0.42 g = 0.97 g
1.01g
% of ammonium chloride 
100%  42.1%
2.40g
0.42g
% of sand 
100%  17.5%
2.40g
0.97g
% of sodium chloride 
100%  40.4%
2.40g
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• Wash all used glassware clean with tap water and put them
back to the bench.
• Dispose of the used sand into the designated waste container.
• Dispose of the used filter paper into trash.
• Wipe your bench and fume hood with wet sponge.
• Ask your instructor to sign you out….then you are ready to
leave.
• Finish the lab report (including both data sheet and postlab
questions) after the lab. Feel free to ask instructors questions,
but never ever copy other students’ answers.
• Turn in the lab report the next time when you are expected to
come to the lab.
• Don’t forget to prepare for the next lab before you come next
time.
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