Basic Skills for Chemistry
CHEM-1020
Experiment No. 2
Measuring Mass and Volume
(Revised 04/11/2016)
Introduction:
In the chemistry laboratory, various kinds of equipment are used to measure length, mass and volume.
In this experiment, you will use two mechanical balances to weigh out specific amounts of a solid
chemical. You will read the volumes of water in three pre-filled graduated cylinders. You will also
choose a graduated cylinder to measure the volume of water held by a glass jar. In the previous
experiment, you examined several analog instruments and learned how to read them. This experiment
reinforces and tests that knowledge. Before you do this experiment, review the directions for
Experiment No. 1 to ensure that you can read graduated cylinders and analog balances properly.
Measurement of Mass: Single, clean objects may be weighed on a laboratory balance by placing
them directly on the balance pan. Prior to weighing an object without a container, zero in the balance
with the zeroing screw adjustment to make the balance read zero grams with no mass in the pan.
Never weigh powdered chemicals, liquids and granular substances directly on a balance. To prevent
contamination and damage to a balance, always weigh chemicals in a container such as a sheet of
weighing paper, a plastic weigh boat, a test tube, a beaker or weighing bottle. One way to measure the
mass of a chemical is to weigh an empty container in a preliminary “tare” step and to subtract that
mass from the total mass of container and chemical to get the mass of chemical alone. When
weighing an object or chemical in a container, do not zero in the balance. Any error due to an
incorrect zero point adjustment will be the same for both masses and will cancel out in the subtraction.
Electronic balances allow you to bypass the mass subtraction step. Simply place a container on an
electronic balance pan and press the tare button. The balance will register the mass of the container as
zero. Then add the desired amount of chemical until the display registers the correct amount. On
many digital balances, a too-heavy container will cause the displayed mass to lose a decimal place. If
weighing a heavy container changes the digital display from 0.001 g to 0.01 g, remove the container,
press the tare button to clear the balance, replace the container with one of lower mass and push the
tare button again.
Measurement of Liquid Volume: For the highest measuring precision, choose the smallest graduated
cylinder that will contain all the liquid that you will measure. After you have determined how the
appropriate graduated cylinder is to be read, pour in the liquid you wish to measure, place the cylinder
on a level surface at eye level and read the volume at the bottom of the liquid meniscus.
Safety: In this and all subsequent experiments in this course, you must wear chemical splash goggles
and a plastic apron at all times, from the very start of any laboratory period. Do not do anything in the
laboratory until you have put on your PPE (personal protective equipment). As soon as you unlock
your laboratory drawer or locker, take out your safety goggles and put them on, making sure they fit
properly and snugly. Next, put on a laboratory apron. After you put on your PPE, you may set up
your equipment and obtain the chemicals you need. When you have finished working, wipe your
laboratory bench and other areas you used with a damp sponge to leave them clean and safe for the
next class. Your chemical splash goggles must be the last thing you take off when you are done. Once
you remove your goggles, you must leave the laboratory immediately.
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Report: You will be graded on the proper use of each instrument and on the accuracy of your
measurements. Be sure to express the units of each measurement, reported result and calculated result.
Experimental: Always examine each instrument before you use it to determine the precision to which
is properly read. Record all your measurements on the data sheet in black ink. To avoid waiting in
line for chemicals or equipment, do not do the following procedures in numerical order. Start by doing
the procedure for which the most equipment is available.
1. Measuring the Mass of a Chemical:
a) Fill a small (50 or 100 mL) beaker less than a quarter full of table salt (sodium chloride, NaCl)
and set it aside. Weigh an empty, clean, dry medium (15 cm long, 1 cm diameter) test tube on a
platform balance three times to check for balance reliability. Record the masses. Your results
should agree to within 0.05 g. Move the 10 g balance rider mass to a position exactly 1.50 g
more than the average of the three empty test tube masses. Record this value on your data sheet.
With a spatula, transfer salt from the beaker to the test tube until the balance beam is in balance
again. Record this value as the combined mass of the test tube and salt. Stopper the test tube
with a cork that fits securely without slipping inside the test tube. Affix an adhesive label to the
test tube with the words: Table Salt, your full name, the letter A, and course number CHEM1020. Submit the test tube and salt for grading by placing it in a container provided by the
instructor. The calculated mass of salt sample A is the difference between your two weighings.
b) Weigh the same small beaker with salt on the hanging pan balance three times to check the
balance reliability. Your results should agree to within 0.010 g. Slide the 1 g balance rider mass
to a position exactly 0.800 g less than the average of the three masses and write that value on
your data sheet. With a spatula, transfer salt from the beaker to an empty medium test tube until
the balance beam balances again. Stopper the test tube with a cork of the correct size. Label
the test tube Table Salt, with your name, the letter B, and CHEM-1020. Turn the test tube in for
grading. The calculated mass of salt sample B is the difference between the two weighings.
c) Place a small empty test tube on the pan of an electronic balance and press the tare button to
register the mass of the test tube as zero. (The digital display should read 0.000 g.) Transfer salt
to the test tube until the balance registers 0.555 g. On your data sheet, record the mass of salt
you added. Stopper the test tube and label it as you did the others but with the letter C. Turn the
test tube in for grading.
2. Measurement of Liquid Volume:
a) Locate three pre-filled graduated cylinders in the laboratory, labeled A, B, and C. Each
graduated cylinder contains an amount of water known to your instructor. Before you attempt
to read the graduated cylinders, examine their markings to determine how to read the devices.
Finally, read and record the volume of water contained in each of the cylinders. If there is
more than one graduated cylinder with the same letter designation, read just one A, one B and
one C cylinder. Include any other identifying information written on the cylinders such as A1,
B3, C2, etc., on your data sheet and in your report.
b) Obtain a bottle representing an unknown volume and record the bottle number. Fill the bottle
to the very top with tap water and measure the volume with the smallest graduated cylinder that
will contain all the water. Report your volume measurement and the size of graduate you used.
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Basic Skills for Chemistry
CHEM-1020
Experiment No. 2
Use of Laboratory Equipment
Data Page
1. Measuring the Mass of a Solid Chemical:
a) Platform Balance
Mass of empty medium test tube:
__________
Average of three masses:
__________
Mass of test tube plus salt sample: __________
Average of three masses:
__________
__________
__________
__________
__________
Calculated mass of salt sample A: __________
(The mass of sample A should be 1.50 g.)
b) Hanging Pan Balance
Mass of beaker and salt before salt sample removal: __________ __________
Average of three masses:
__________
__________
Mass of beaker and salt after removal of salt sample: __________ __________
__________
Average of three masses:
__________
Calculated mass of salt sample B:
__________ (The mass should be 0.800 g)
c) Digital Balance
Mass of salt sample C:
__________ (The mass should be 0.555 g)
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2.
Measurement of Liquid Volumes:
a) Water Volumes in Pre-Filled Graduated Cylinders:
Graduated Cylinder A_____: Cylinder Size: __________
Water Volume:____________
Graduated Cylinder B_____: Cylinder Size: __________
Water Volume:____________
Graduated Cylinder C_____: Cylinder Size: __________
Water Volume:____________
b) Volume of Water Held by an Unknown Bottle:
Bottle number: ________
Size of graduated cylinder used:
Volume of water contained by unknown bottle:
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_____________
_____________
Basic Skills for Chemistry
CHEM-1020
Experiment No. 2
Use of Laboratory Equipment
Report
1. Measuring the Mass of a Solid Chemical:
2.
a) Mass of salt sample A handed in: __________
(2 points)
b) Mass of salt sample B handed in: __________
(2 points)
c) Mass of salt sample C handed in: __________
(2 points)
Measurement of Liquid Volumes:
a) Water Volumes Read from Pre-filled Graduated Cylinders:
(6 points)
Graduated Cylinder A____: Cylinder Size: _________
Water Volume:___________
Graduated Cylinder B____: Cylinder Size: _________
Water Volume:___________
Graduated Cylinder C____: Cylinder Size: _________
Water Volume:___________
b) Volume of Water Held by an Unknown Bottle:
Bottle number: ________
Size of graduated cylinder used:
Volume of water contained in unknown bottle:
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(2 points)
___________
___________
3. Describe the complete process for analyzing any analog laboratory instrument and determining the
proper way to read it.
(2 points)
4. What is the total mass of the three salt samples you weighed out in parts 1a, 1b and 1c? Use the
formula mt = ma + mb + mc. Show the setup for your calculation.
(2 points)
5. What is the total volume of water contained in the three graduate cylinders in part 2a? Use the
formula VT = VA + VB + VC. . Show the setup for your calculation.
(2 points)
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