CHEMISTRY IN CONTEXT
LAB 3: MEASURING, PAGE 1
CYCLE 2
NAME
Using Measuring Devices
PRE-LAB/DISCUSSION:
Recall that there are THREE essential BASE measurements in science: mass, length,
and volume. The units we will MOST often use for each are grams and kilograms for
mass, centimeters for length, and milliliters for volume. Take a look at the following
chart and FILL IN the missing information:
UNIT
SYMBOL
MEASURES
g
mass
DEVICE
kilogram
flask, beaker,
graduated cylinder,
and pipette
mL
length
The base units in science can also be used to determine derived units. Derived units
are combinations of base units. For example, density tells you how heavy something is
for each unit of space that it takes up. For example, a bowling ball and inflated balloon
may be about the same size and take up the same amount of space, but the bowling
ball is DEFINITELY heavier. So, its density is greater. You can calculate density by
dividing the mass by the volume.
In today’s lab, you will be measuring the density of water, isopropyl alcohol, and
aluminum shot by three varying methods.
Some important safety reminders:
1)
You will be using ALUMINUM SHOT today which can produce a powder
when poured. The powder is a lung irritant if inhaled and also HIGHLY
FLAMMABLE. So, we will be using the shot under the fume hood so that
when it is poured, the powder vapors will be sucked out of the room.
2)
You will also be using ISOPROPYL ALCOHOL, a minor skin irritant.
Isopropanol is flammable if exposed to direct flame, so keep it away from
outlets and avoid inhaling the vapors as they may make you feel nauseous.
Safety First, Go To It!
CHEMISTRY IN CONTEXT
LAB 3: MEASURING, PAGE 2
CYCLE 2
NAME
APPARATUS/MATERIALS:
1 plastic ruler (located at main lab bench)
1 plastic pipette (located at main lab bench)
1 small zip sandwich bag (ONLY if you do NOT have one in your cabinet with
sand already in it -- located at main lab bench)
dark coarse sand (located at main lab bench)
1 100mL graduated cylinder
1 250mL graduated cylinder
1 50mL beaker
1 250mL beaker
1 100mL beaker
triple beam balance
microscale digital balance (COMMUNITY resource, for smaller samples, located
under fume hood)
macroscale digital balance (COMMUNITY resource, for larger samples, located
under wipe board)
1 plastic massing dish (COMMUNITY resource, located under fume hood)
PROCEDURE:
Part A: Aluminum Shot
1)
Take your 100mL graduated cylinder to the fume hood. Use the spatulas at
the fume hood to measure out 10mL of aluminum shot into your graduated
cylinder.
2)
Select a microscale digital balance and look at what the screen reads. Then,
take a plastic massing dish and place it on the balance. Press the tare
button. What did the tare button do?
3)
Carefully pour your 10mL of aluminum shot into the plastic massing dish on
the balance. Be careful NOT to allow the aluminum shot to spill and make
SURE all the shot is OUT of the graduated cylinder by tapping the end of the
cylinder (some times it can stick to the sides). Record the mass of the 10mL
of aluminum shot and carefully pour the shot back into the large storage
beaker. Return to your lab bench and calculate the density of the aluminum
shot (HINT: The formula for density was described in your prelab/discussion.)
Part B: Water
1)
Take out your triple beam balance. IF there is a small plastic zip sandwich
bag of sand stored in your lab cabinet with your balance, then proceed to
Step #4. If not, go to Step #2.
CHEMISTRY IN CONTEXT
LAB 3: MEASURING, PAGE 3
CYCLE 2
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NAME
Set ALL of your weight markers (three tracks) to the zero setting (all the way
to the left).
 If the black arrow on the far right side of your balance lines up with the
white mark for zero OR is within 0.6cm of the white mark (use your
ruler to check), then proceed to Step #5.
 If it is more than 0.6cm ABOVE the white
line, use the tip of a pencil or pen to
carefully slide the small brown marker on
the FIRST track (smallest marker) out
UNTIL the black arrow lines up with the
white mark and proceed to Step #5.
 If it is more than 0.6cm BELOW the white
line, then send your lab partner to the main
lab bench to half fill a 250mL beaker with
sand AND acquire a small zip sandwich
bag.
Add some sand to your sandwich bag and place
it on the balance. If the black arrow on the right
side jumps up way above the white line, then
remove sand until the arrow and white mark are
within 0.6cm of one another (use your ruler to help.) Seal your sandwich bag,
and return the remainder of your sand to the main lab bench and rinse your
beaker.
Place your sandwich bag on your balance. From now on, it will ALWAYS be
necessary to have your sandwich bag sitting on your balance before using it
to measure any mass.
Place your 250mL graduated cylinder on the balance and measure its mass
using the technique demonstrated at the beginning of class by your instructor.
Record the value.
Fill your 250mL graduated cylinder to 110mL. When reading your graduated
cylinder volume always read the meniscus water mark, this is the bottom of
the curved surface created by the top level of the water in your cylinder. (See
the picture as an example for a measurement of 40.575mL just remember
that YOU are measuring out 110mL!)
Place your 250mL graduated cylinder with the 110mL of water on the balance
and measure its mass using the technique demonstrated at the beginning of
class by your instructor. Record the value.
Subtract the two values to determine the mass of the water.
Calculate the density of the water (HINT: The formula for density was
described in your pre-lab/discussion.) Pour the water down the drain and put
away these lab materials.
CHEMISTRY IN CONTEXT
LAB 3: MEASURING, PAGE 4
CYCLE 2
NAME
Part C: Isopropyl Alcohol (isopropanol)
1)
Use the macroscale digital balance to measure the mass of a clean, dry 50mL
beaker.
2)
Then, at the main lab bench, use the 1mL pipettes to carefully transfer 10mL
of isopropyl alcohol to the small beaker. Read the SIDE of the plastic pipette
to find the 1mL mark. You will need to fill the pipette to JUST this mark 10
times to get the transfer. DO NOT use the 10mL mark on the side of the
beaker to determine if you have 10mL. (You may need to practice a few
times to get it right!) Notice where the top level of the alcohol is after your
transfer. Is it lined up with the 10mL mark on the beaker?
3)
Use the macroscale digital balance to measure the mass of the 50mL beaker
with 10mL of isopropyl alcohol.
4)
Subtract the two values to determine the mass of the isopropyl alcohol.
5)
Calculate the density of the isopropyl alcohol (HINT: The formula for density
was described in your pre-lab/discussion.)
6)
Pour the isopropyl alcohol back into the Erlenmeyer flasks at the main lab
bench and rinse and dry out your beaker. Put it away.
DATA/OBSERVATIONS:
Part A: Aluminum Shot:
Mass of 10mL of aluminum shot:
g
Density of aluminum shot:
g/mL
Part B: Water
Mass of 250mL graduated cylinder:
g
Mass of 250mL graduated cylinder + 110mL of water:
g
Mass of the 110mL of water:
g
Density of water:
g/mL
CHEMISTRY IN CONTEXT
LAB 3: MEASURING, PAGE 5
CYCLE 2
NAME
Part C: Isopropyl alcohol
Mass of 50mL beaker:
g
Mass of 50mL beaker + 10mL isopropyl alcohol:
g
Mass of the 10mL of isopropyl alcohol:
g
Density of isopropyl alcohol:
g/mL
ANALYSIS:
1)
Answer the question in Step #2 of Part A.
2)
Answer the question in Step #2 of Part C.
3)
What is the meniscus?
4)
Write the following in order from HIGHEST density to LOWEST density:
water, isopropyl alcohol, aluminum shot
5)
What was MOST difficult about this lab? Why?
6)
Which balance do you think is MOST ACCURATE? Digital balances or triple
beam balances? Why?