Experiment 1 – Measurements
Name __________________
Lab Section __________________
Experiment 1 – Measurements
Introduction
Measurements are made on a daily basis, many times without thinking about it. How tall are
you? How much orange juice is in that glass? How hot was it yesterday? How much does this
backpack full of books weigh? How long until lab the pasta is ready? All of these questions are
answered by measuring a quantity. In the aforementioned cases, length, volume, temperature,
mass, and time were being measured. Depending on how well the measurement device is, a
better or worse value can be reported.
In science the metric system is used for measuring these quantities. It is a simple and effective
measurement system based on powers of ten and uses five base measurements to quantify
physical properties. These five base measurements are length, volume, temperature, mass, and
time. They are represented by the quantities meter (m) or centimeter (cm), liter (L) or
milliliter (mL), temperature (°C or K), gram (g) or kilogram (kg), and seconds(s),
respectively.
Though measurement tools become better and better all the time, there is still some uncertainty
in any measurement that is made. As you will see in this lab, depending on what measurement
tool you use, the precision to which you can report the value will change. Some numbers will be
very precise, others not as much. How good the measurement too is will be reflected in the
amount of significant figures you can report in the value.
Every measuring device has a given uncertainty in its measurement. A centimeter ruler is only
valid out to the nearest ±0.1cm, while the millimeter ruler is valid out to the nearest ±0.05 cm.
A graduated cylinder is valid to the nearest ±0.5 mL, and a thermometer has an uncertainty of
±0.5°C. Each of the measuring devices listed above involve a human estimation of equipment,
that is to say a judgment call of “just where the end or meniscus lay” is involved. The balance is
the only measurement tool where the estimation has been done by the machine, and the number
reported requires no estimation. What is reported by the balance is what you record. In the case
of the milligram balance, the error is ±0.001 g. Below you will find examples of each of these
measurements.
After all base measurements have been made; compound units can be derived from these. Units
such as speed (length per time), density (mass per volume), and volume derived from lengths
(e.g. 𝑐𝑚3 ) can be calculated and their values reported. This utilizes the rules for determining
significant figures, and your number should be reported as such.
Experiment 1 – Measurements
Name __________________
Lab Section __________________
Examples
Measuring with Ruler
Centimeter Ruler
Since the markings on the centimeter ruler are only every integer, the object can only be read
to within ±0.1 cm.
5.3 cm
Millimeter Ruler
There are finer gradations on the millimeter ruler, allowing for a more precise measurement
of the object. Here the tenths measurements are clearly marked, and the estimation of the
measurement can be made out to ±0.05 cm.
5.35 cm
Experiment 1 – Measurements
Name __________________
Lab Section __________________
Measuring with a Graduated Cylinder
When liquid is placed into a graduated cylinder a meniscus is formed. A meniscus (from the
Greek meniskos, meaning “lunar crescent”) is a concave formation of the water in the tube.
Measurements are made from the bottom of the meniscus. Due to how the gradations are
marked on the cylinder, a measurement of only ±0.5 mL can be reported,
60.0 mL
46.5 mL
Measuring with a Thermometer
Due to the gradations on the thermometer, it is only possible to record temperatures to
±0.5°C.
26.5°C
20.0°C
Experiment 1 – Measurements
Name __________________
Lab Section __________________
Reading a Buret
Just like a graduated cylinder, a buret has a meniscus and much be read in a similar fashion. The
error on a buret, however, is ±0.05 mL.
31.65 mL
Calculating Volumes from Length Measurements
Centimeter Ruler
A rectangular solid was measured using a centimeter ruler. It measured 2.5 cm by 1.2 cm by
11.1 cm. What is the volume of the solid?
(2.5 𝑐𝑚)(1.2 𝑐𝑚)(11.1 𝑐𝑚) = 33.3 𝑐𝑚3 → 𝟑𝟑 𝒄𝒎𝟑
Note: the least amount of significant figures in the original data is two. Following the
rules for significant figures, the volume should only be reported to two significant
figures.
Millimeter Ruler
A rectangular solid was measured using a centimeter ruler. It measured 2.55 cm by 1.20 cm
by 11.15 cm. What is the volume of the solid?
(2.55 𝑐𝑚)(1.20 𝑐𝑚)(11.15 𝑐𝑚) = 34.119 𝑐𝑚3 → 𝟑𝟒. 𝟏 𝒄𝒎𝟑
Note: the least amount of significant figures in the original data is three. Following the
rules for significant figures, the volume should only be reported to three significant
figures.
Experiment 1 – Measurements
Name __________________
Lab Section __________________
Procedure
Mass Measurements
For all mass measurements, perform the following procedure. Tare (zero) the balance and
wait until it reads 0.000 g. Place the indicated item on the balance and record its mass. The
three items to weigh are: a pencil, an Erlenmeyer flask, and a 100 mL beaker.
Length Measurements
Measure the length of a credit card, small test tube, and a watchglass using both the
centimeter and millimeter rulers. It is easiest to measure the diameter of the watchglass by
placing it “hump up” on the ruler. Be sure to keep the correct precision of each ruler in your
data (i.e. one decimal place for the centimeter ruler, two for the millimeter ruler).
Temperature Measurements
Read the temperature of a thermometer sitting at room temperature.
Read the temperature of a thermometer sitting in an ice bath. Note, you may need to stir the
batch to remove any temperature gradients. If so, wait until the mark is stable and record the
temperature.
Read the temperature of a thermometer in boiling water
Note: all temperature measurements can be made to within ± 0.5°C
Experiment 1 – Measurements
Name __________________
Lab Section __________________
Volume Measurements
Partially fill a 100 mL beaker with water. Record the volume of water you put into the
beaker. Note: you should not be able to indicate anything more than precision in the tens
place.
Fill a 100 mL graduated cylinder to nearly ¾ full. Record this volume. Pour out some water
and rerecord the volume. Pour out yet more water and rerecord the volume. Note: a graduate
cylinder can be read to within ± 0.5 mL.
Read the volume on the partially filled buret provided to you by your instructor. If the bottom
of the meniscus is difficult to read, place your hand behind the buret, or use a reading card.
Note: the buret can be read to within ± 0.05 mL
Unknown Solid
Obtain an unknown solid from your instructor.
Record its mass and measure its length, width, and height dimensions using both the
centimeter and millimeter rulers.
Calculate the volumes you obtain from the different ruler measurements of the solid’s
dimensions. Be sure to use significant figures.
Equipment Needed:
Pencil
Erlenmeyer flask
100 mL beaker
Credit card/I.D. card
Small test tube
Watchglass
Graduated Cylinder
Unknown sample
Experiment 1 – Scientific Measurements
Name __________________
Lab Section __________________
Prelaboratory Questions
What are the five base measurements and their units?
What is meant by “uncertainty”? Please give an example.
What are the uncertainties of all quantities you will measure in this lab?
In the figures below, please indicate the value that would be reported.
Experiment 1 – Scientific Measurements
Name __________________
Lab Section __________________
Data Table
Mass Measurements
Mass of a pencil
_________________ g
Mass of an Erlenmeyer flask
_________________ g
Mass of a 100 mL beaker
_________________ g
Length Measurements
Length of credit card
Centimeter ruler
_______________ cm
Millimeter ruler
_______________ cm
Length of small test tube
Centimeter ruler
_______________ cm
Millimeter ruler
_______________ cm
Diameter of watchglass
Centimeter ruler
_______________ cm
Millimeter Ruler
_______________ cm
Temperature Measurement
Room Temperature
_______________ °C
Ice Water Bath
_______________ °C
Boiling Water
_______________ °C
Experiment 1 – Scientific Measurements
Name __________________
Lab Section __________________
Volume Measurement
Volume inside 100 mL beaker
_______________ mL
Volume inside graduated cylinder
_______________ mL
- Minus first pour
_______________ mL
- Minus second pour
_______________ mL
Volume inside buret
_______________ mL
Unknown Solid
Mass of solid
________________ g
Volume of solid
Length of solid – centimeter ruler
_______________ cm
Width of solid – centimeter ruler
_______________ cm
Height of solid – centimeter ruler
_______________ cm
Volume of solid – show calculation
_______________ cm3
Volume of solid
Length of solid – millimeter ruler
_______________ cm
Width of solid – millimeter ruler
_______________ cm
Height of solid – millimeter ruler
_______________ cm
Volume of solid – show calculation
_______________ cm3
Experiment 1 – Scientific Measurements
Name __________________
Lab Section __________________
Postlaboratory Questions
1) Please indicate how many significant figures are in the following numbers:
152
__________
0.0031
__________
100.0
__________
1001
__________
0.120
__________
1500.08
__________
15000
__________
0.03040
__________
105000
__________
2) Perform the following calculations and report the answer in correct significant figures:
+
157.231
43.51
g
g
(0.55 cm)(10.1 cm)
-
149.735
31.1
g
g
149.175 g
25.5 mL
+
1500 cm
10 cm
-
950
10
mL
mL
(48.25 cm)(19.1 cm)(0.50 cm)
3) The ball of iron below weighs 55.265 g and measures 3.00 cm in diameter. What is the
4
density of the iron ball? (𝑉 = 3  𝑟 3, where r is the radius)