Lab 1: Measurement
Introduction
In this lab, you are asked to make a series of mass, volume and temperature measurements and
record the number of significant figures and units in each measurement.
Mass measurement involves determining the mass of the sand in a vial.
Three stations will be set up in the laboratory. Each station is set up for you to determine the two
volume measurements and a temperature measurement. The measuring instruments at the three
stations are:
1. a graduated cylinder for volume measurement
2. a buret for volume measurement
3. a temperature for temperature measurement
Volume measurements can be made with various types of glasswares. The glassware that is used
determines the accuracy of the measurement.
In all the measurement determination, it is important that you pay attention to:
1. the determination of the value of the measurement,
2. the unit that is associated with the measurement,
3. the proper number of significant figures that is associated with the measurement.
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Introduction to the Analytical Balance
Weighing a sample is often the first step in many quantitative analytical methods. An analytical
balance measures masses to within 0.0001 g. Balances are sensitive to drafts, changes in
temperature, or the vibrations caused by moving people. The balances are stored in a separate
room to minimize these variables and are placed on concrete tables. Balances are very expensive
and are sensitive to attack by corrosive chemicals. Do not take liquid into the balance room.
When possible, chemicals should be added to the weighing container outside of the balance
chamber. It is important that you clean up all chemical spills.
In this experiment, you will learn to use the balance properly and be aware of the common errors.
Introduction to Volumetric Glassware
When performing a chemistry lab, the procedure may include using various types of glassware
for volume measurements. In order to accurately perform the lab procedures, an understanding of
the different types of glassware is required. Each piece of glassware is made to certain
specifications. That is, there is a maximum measurement error associated with the glassware
known as the tolerance. For example, a flask which holds 5.00 mL of liquid has a tolerance of
±0.02 mL (or ±0.4 %). This means that the actual volume that the flask holding is in the range of
4.98 to 5.02 mL. In order to avoid introducing a significant error to the analytical result, the
tolerance specifications of each piece of volumetric glassware must match the required accuracy
of the procedure.
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The following is a summary of the various types of glassware and their tolerance.
Accuracy of the Various Types of Graduated Glasswares
Type of Glassware
Accuracy
Target
Volume
Accuracy Range
Graduated Erlenmeyer flask
± 10%
100 mL
100 mL ± 10 mL
roughly accurate
Graduated beaker
± 5%
100 mL
100 mL ± 5 mL
roughly accurate
Graduated cylinder
± 0.5%
100 mL
100 mL ± 0.5 mL
accurate
Volumetric flask
± 0.1%
100 mL
100 mL ± 0.1 mL
very accurate
Volumetric pipet
± 0.05%
100 mL
100 mL ± 0.05 mL
very accurate
Buret
± 0.01%
100 mL
100 mL ± 0.01 mL
very accurate
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Volume Measurements – Graduated Cylinder
In any volume measurement we need to approach the measuring instrument at proper eye
position, at eye level. When we are up close to the liquid level at eye level, we will observe that
the surface of the liquid forms a "lens-shaped". This is called the meniscus. In taking the
measurement, we always read the bottom of the meniscus. Below is an example of a reading
taken of a liquid in a graduated cylinder. The diagram shows an expanded view of the portion of
the cylinder near the surface of the liquid.
Let's analyze this measurement:
1. Upon inspection of the graduated cylinder,
we observe that the finest division is a
1 mL division.
2. We can always make an estimate of a
reading to within the finest division.
Therefore, to the best of my judgement, I
conclude that this particular graduated
cylinder is able to provide a reading
accuracy to ± 0.2 mL. (Note: A plus or
minus 0.2 mL reading accuracy means that a
volume measurement using this graduated
cylinder will contain uncertainty in the first
decimal place.)
3. The bottom of the meniscus lines up with
the 4th finest division above the 10 mL
mark.
4. The volume reading is determined to be
14.0 mL. This volume reading has 3
significant figures. (Note: the '0' in this
measurement is an uncertain figure. This
measurement is accurate to 14.0 ± 0.2 mL. It
means that using this graduated cylinder, the
accuracy of the volume of the liquid is
between 13.8 mL to 14.2 mL.)
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Volume Measurements – Buret
In any volume measurement we need to approach the measuring instrument at proper eye
position, at eye level. When we are up close to the liquid level at eye level, we will observe that
the surface of the liquid forms a "lens-shaped". This is called the meniscus. In taking the
measurement, we always read the bottom of the meniscus. Below is an example of a reading
taken of a liquid in a buret. The diagram shows an expanded view of the portion of the buret near
the surface of the liquid.
Let's analyze this measurement:
1. Upon inspection of the buret, we observe
that the finest division is a 0.1 mL division.
2. We can always make an estimate of a
reading to within the finest division.
Therefore, to the best of my judgement, I
conclude that this particular buret is able to
provide a reading accuracy to ± 0.02 mL.
(Note: A plus or minus 0.02 mL reading
accuracy means that a volume measurement
using this buret will contain uncertainty in
the second decimal place.)
3. The bottom of the meniscus lines up with
the 6th finest division below the 34 mL
mark.
4. The volume reading is determined to be
34.60 mL. This volume reading has 4
significant figures. (Note: the '0' in this
measurement is an uncertain figure. This
measurement is accurate to
34.60 ± 0.02 mL. It means that using this
buret, the accuracy of the volume of the
liquid which has been dispensed is between
34.58 mL to 34.62 mL.)
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Temperature Measurements – Thermometer
In any temperature measurement we need to approach the measuring instrument at proper eye
position, at eye level. When we are up close to the mercury level at eye level, we will observe that
the surface of the mercury forms a "lens-shaped" that bulges upward. This is called the meniscus.
Unlike the meniscus that we observe with a liquid like water, the mercury forms a positive
meniscus. In taking the measurement, we always read the top of the positive meniscus. Below is
an example of a temperature reading. The diagram shows an expanded view of the portion of the
thermometer near the surface of the mercury.
Let's analyze this measurement:
1. Upon inspection of the
thermometer, we observe that the
finest division is a 1 oC division.
2. We can always make an estimate of
a reading to within the finest
division. Therefore, to the best of
my judgement, I conclude that this
particular thermometer is able to
provide a reading accuracy to
± 0.2 oC. (Note: A plus or minus
0.2 oC reading accuracy means that
a temperature measurement using
this thermometer will contain
uncertainty in the first decimal
place.)
3. The top of the positive meniscus
almost lines up with the 30 oC
mark.
4. The temperature reading is
determined to be 29.8 oC. This
temperature reading has 3
significant figures. (Note: the '8' in
this measurement is an uncertain
figure. This measurement is
accurate to 29.8 ± 0.2 oC. It means
that using this thermometer, the
accuracy of the temperature is
between the range 29.6 oC to
30.0 oC.)
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Procedure
Note: Parts A, B, and C can be done in any order.
Part A: Mass measurement
1. Place an empty weighing boat on the analytical balance and zero the balance.
2. Obtain a vial of sand and carefully empty the content of the vial on the weighing
boat.
3. Record the mass of the sand and the unit of the measurement on the data sheet
and determine the number of significant figures of the recorded measurement.
Part B: Volume measurements
Three stations are set up in the laboratory. At each station take:
1. the volume reading of the buret
2. the volume measurement of the graduated cylinder
3. Record the volume measurements and the units of the measurements on the
data sheet and determine the number of significant figures of the recorded
measurements.
At the end of Part B, you should have recorded 6 volume measurements:


3 buret readings
3 volume measurements of the graduated cylinders
Part C: Temperature measurements
Three stations are set up in the laboratory. At each station take:
1. the temperature reading of the thermometer
2. Record the temperature measurements and the units of the measurements on
the data sheet and determine the number of significant figures of the recorded
measurements.
At the end of Part C, you should have recorded 3 temperature measurements.
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Experiment 1 - Measurement
Name:__________________________
Date_______________
Data:
Part A: Mass measurement
Vial Number
Number of Significant Figures
Recorded in the Measurement
Mass
Part B: Volume measurements
Graduated Cylinder
Measurement
Number of Significant Figures
Recorded in the Measurement
Volume
Station A
Station B
Station C
Buret Reading
Number of Significant Figures
in the Volume Dispensed
Volume
Final Reading :
Station A
Initial Reading :
3.55 mL
Volume Dispensed:
Final Reading :
Station B
Initial Reading :
0.80 mL
Volume Dispensed:
Final Reading :
Station C
Initial Reading :
1.00 mL
Volume Dispensed:
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Part C: Temperature measurements
Thermometer
Reading
Temperature (°C)
Temperature (K)
Number of Significant Figures
for the Temperature in Kelvin
Station A
Station B
Station C
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