Chemistry
LAB 1: MEASUREMENTS
The basis for any scientific investigation is measurement. The ability to measure accurately the quantities
of the experiment is crucial to the success of the experiment. This lab will allow you to practice your skill
in using various measurement devices.
Precision - Precision is the term related to the accuracy of the device itself. It is generally considered to
be 1/10th of the smallest division of the instrument. For example, centimeter-type rulers generally have
marks for each millimeter--one millimeter (mm) would be the smallest division, so the precision of that
ruler would be 1/10th of a mm, or 0.1 mm, or 0.01 cm. An experienced person, under the right
conditions, should be able to estimate to the precision of the device.
Uncertainty - Uncertainty is the term used to describe how good a measurement is. The uncertainty of a
measurement may be larger than the precision but not smaller - the smallest uncertainty cannot be "better"
than the precision! You will have to estimate the uncertainty for each measurement made. Depending on
the tools available, you may have to "eyeball" a measurement, thus creating a larger uncertainty. For
example, to measure the diameter of a ball with a ruler, you cannot be expected to estimate to the
precision of the ruler--your measurement would have a larger uncertainty, maybe a few millimeters. The
uncertainty of the measurement is based on your reasonable judgment of how accurate your value is-therefore, the uncertainty is the precision of the device. The word tolerance is also used interchangeably
with uncertainty.
Accuracy - Accuracy generally means the uncertainty of the measurement itself. Percentage uncertainty
(parts per hundred) or parts per thousand, etc. is the best way to express accuracy for comparisons of
unrelated measurements.
If a device has a high level of precision, it is easier for multiple individuals to arrive at similar
measurements. However, when different people are making the measurements, there will be a degree of
uncertainty introduced based on individual bias. In this lab, you will make measurements will
instruments of differing levels of precision and compare these same measurements to those made by other
students.
SAFETY
 Be careful of sharp edges and objects while measuring to avoid cuts. If any cuts occur, notify
your teacher for treatment.
 Never put broken glass in a regular waste container. Broken glass should be disposed of
properly.
MATERIALS
Metric ruler
Calculator
Pencil
Textbook
Plastic cylinder
Lab 1: Measurements
Graduated cylinder
Water
Beaker
Funnel
Buret
Thermometer
Balance
Pipet
Pipet bulb
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Chemistry
PROCEDURE
1. Form a group of four students by combining two lab groups and obtain materials from your
teacher. Your group will share the materials, but all measurements will be made with your lab
partner and then shared with the other group.
2. Using the metric ruler, measure the length of the pencil. Be sure to measure to one uncertain
digit. Record this measurement in Data Table 1.
3. Using the metric ruler, measure the length, width, and thickness (height) of the textbook. Record
these measurements in Data Table 1.
4. Using the metric ruler, measure the height and diameter of the plastic cylinder. Record these
measurements in Data Table 1.
5. Place the empty cylinder on a balance and record the mass in Data Table 2.
6. Using a buret, completely fill the cylinder with water. Record the initial volume in the buret and
the volume after you have filled the cylinder in Data Table 2.
7. Place the filled cylinder on a balance and record the mass in Data Table 2.
8. Using the funnel to prevent spills, transfer the water from the cylinder to the beaker. Use the
markings on the beaker to measure the volume of water to one uncertain digit. Record this value
in Data Table 2.
9. Transfer the water from the beaker to a graduated cylinder. Use the markings on the graduated
cylinder to measure the volume of water to one uncertain digit. Record this value in Data Table
2.
10. With the thermometer provided, measure the temperature of the water in the beaker. Record this
value in Data Table 2.
11. Obtain measurement data from the other group. Record these in the appropriate spaces in Data
Tables 1-2.
12. Add water to the beaker until the water is at least 1" deep. Using a pipet and bulb, remove 5.0
mL of water from the beaker as accurately as possible. Practice pipetting different amounts from
the beaker. Your next lab will require accurate pipetting abilities so make sure you can do this.
13. Discard the water, dry the equipment, and return everything to your teacher.
OBSERVATIONS/DATA/CALCULATIONS
Record all of your measurements in Data Tables 1 and 2. Make note of any qualitative observations
during the lab as well.
Data Table 1: Ruler Measurements
Measurement
Group 1 Value
Pencil Length
Group 2 Value
Unit
Textbook
Textbook Length
Textbook Width
Textbook Height
Cylinder
Cylinder Height
Cylinder Diameter
Lab 1: Measurements
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Chemistry
Data Table 2: Plastic Cylinder Measurements
Measurement
Group 1 Value
Temperature of Water
Group 2 Value
Unit
Mass
Mass of Empty Cylinder
Mass of Filled Cylinder
Volume
Initial Volume in Buret
Final Volume in Buret
Volume of Water in Beaker
Volume of Water in Graduated Cylinder
Data Table 3: Calculations
Measurement
Volume of Textbook
Group 1 Value
Group 2 Value
Unit
Volume of Cylinder
Mass of Water Added to Cylinder
Volume of Water Added to Cylinder
Density of Water (Calculated)
Density of Water (Actual)
--
% Error for Density Calculation
ANALYSIS
1. Complete Data Table 3. To determine the volume of the textbook and cylinder, use volume
formulas for regular prisms. Look up the density of water at the temperature you measured.
Record this value as the actual density of water.
2. How many significant digits were you able to record using the following instruments:
a. Ruler
b. Thermometer
c. Balance
d. Buret
e. Beaker
f. Graduated cylinder
3. You recorded the volume of the water in the cylinder using three different instruments. Were
there any differences between the three readings? If so, explain what could have caused these
differences.
4. Was the density of water you calculated too high or too low? Explain what could have caused
this difference. Be sure to indicate why your calculation came out high/low.
Lab 1: Measurements
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Chemistry
5. From the measurements taken in the lab, were the data between the two groups exactly the same
or different? Describe which measurements had the largest discrepancies and account for this
fact.
6. Define systematic error and random error. Which error do you think was more prevalent in this
lab?
7. You have been asked to measure out each of the following amounts of water. For each, give the
volumetric instrument you would choose to do so and explain why.
a. About 30 mL
c. 40.2 mL
b. 28.50 cm3
d. 2 L
8. If you were asked to measure 1.000 g of a solid, should you use the balances used in this lab?
Why or why not?
REPORT
Write a formal lab report in your lab notebook. Be sure to include all of the following sections.
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Title
Procedure
Lab 1: Measurements
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Observations
Data
Calculations
Post Lab Analysis
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