Chemistry Lab on measurements- mass, length, volume, and temperature

Making Measurements

INTRODUCTION

Chemistry is an experimental science. When gathering information in an experiment the
data often involves quantitative, or numerical, measurements. It is important to learn how
to make and use these measurements properly. In this lab, you will learn how to correctly
make measurements involving mass, length, volume, and temperature.

Units
The units used are from the metric system. The unit of length is the meter (m); of volume,
the liter (L); of mass, the gram (g); and of temperature, degrees Celsius (oC). In the metric
system the unit is made larger or smaller by adding prefixes, such as centi- and kilo- (with
the exception of temperature).

Making Measurements
Some equipment used for making measurements has marks on the equipment that indicate
the value of the measurement. When making measurements it is important to be as precise
as possible. In lab you will record the digits shown on the measuring device plus one
estimated digit. The last digit will be determined by estimating the distance between the
smallest increments on the marked scale. The final digit represents the best guess about
where the object falls relative to the markings on the instrument and is always the least
certain digit.

The estimated digit tells us how close we are to the smallest marking we can read.
When making our measurements, we always estimate one digit past the smallest
marked increment.

Example 1:

Suppose we are measuring the length of the red line in the image above. The ruler has
numbered markings in the ones place. When making the measurement, the known value
for the centimeter is 2 cm. Between 2 cm and 3 cm there are 10 lines. That means each line
represents 0.1 cm. The red line is between 0.3 and 0.4 (between the 3rd and 4th lines). With
certainty the measurement is 2.3 cm. To make the most precise measurement the last digit
is estimated. In this case, the estimated digit will be to the 0.01 place. Because the line falls
just before the halfway between the two markings, the estimated digit could be 0.04, giving
a recorded measurement of 2.34 cm. Summary: the ruler has marked lines to the tenths
place, so the estimated digit would be in the hundredths place.

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Example 2:

Suppose we are measuring temperature using the thermometer in the picture. The
thermometer has numbered markings in tens place of oC. Between 0oC and 10oC there are
10 lines. That means each line represents 1oC. The blue liquid is between 2oC and 3oC
markings (between the 2nd and 3rd lines). With certainty the measurement is 2oC. To make
the most precise measurement, the last digit is estimated. In this case, the estimated digit
will be to the 0.1 place. Because the line falls just before the 3rd mark, the estimated digit
could be 0.8, giving a recorded measurement of 2.8oC. Summary: the thermometer has
marked lines to the ones place, so the estimated digit would be in the tenths place.

Example 3:

Let’s look at two different graduated cylinders for comparison. The graduated cylinder on
the left is a 10-mL graduated cylinder and the cylinder on the right is a 100-mL graduated
cylinder. When measuring the volume of a liquid, read the meniscus of the liquid (the
lowest part of the curve) at eye level.

10-mL graduated cylinder: The cylinder has numbered markings in one’s place of mL.
Between 9mL and 10mL there are 10 marking lines. That means each marked line
represents 0.1mL. The meniscus of the water is between 0.6 mL and 0.7 mL. With
certainty the measurement is 9.6 mL. To make the most precise measurement, the last
digit is estimated. In this case, the estimated digit will be to the 0.01 place. Because the
line falls just before the 7th mark, the estimated digit could be 0.09, giving a recorded
measurement of 9.69 mL. Summary: this 10-mL graduated cylinder has marked lines to
the tenths place, so the estimated digit would be in the hundredths place.

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100-mL graduated cylinder: The cylinder has numbered markings in tens place of mL.
Between 10mL and 20mL there are 10 marking lines. That means each marked line
represents 1mL. The meniscus of the water is right on the 21 mL marked line. With
certainty the measurement is 21 mL. To make the most precise measurement, the last digit
is estimated. Because we know the measurement to the ones place, the estimated digit will
be 0.1 place. In this case, where the measurement falls on a marked line, the estimated
digit could be 0.00, giving a recorded measurement of 21.0mL. Summary: this 100-mL
graduated cylinder has marked lines to the ones place, so the estimated digit would be
in the hundredths place. In the event the estimated digit is on the line, use 0 as the
estimated digit.

Some equipment used for making measurements is digital. When using digital equipment
to make a measurement, record all of the digits presented. You do not round or add to the
digits shown on a digital device. The digital scale below is an example of a digital
instrument.

Making and recording measurements in science is fundamental. Scientists
communicate ideas and come to conclusions through measurements. It is important
to represent these values to the best of our ability.

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Measurements Activity:
In this lab we will be measuring volume, length, and temperature.

Prepare your notebook. When the lab is complete your lab notebook should
include the following:

2. Write the title of the lab on the top of the page.
3. Date/number the page (if you work on it over a few days, date each time you are

4. Record the Purpose of Experiment in your own words. Remember the purpose is the

overall question that will be answered by collecting the data and doing any
requested calculations.

5. Indicate PPE (personal protection equipment) required while performing the lab:
goggles, closed-toed shoes

6. Complete the measurement practice below. Record ANSWERS ONLY in your
notebook.

7. Copy the four tables in the Procedure in your notebook.

Measurement Practice: For each of the following, record the measurement. Remember
to include the estimated digit and the units.

gram (g) scale

Centimeter (cm) scale

Celsius (oC) scale

Procedure: Remember to make all measurements to the correct precision

Materials/Equipment needed:
Thermometer water

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The purpose of this experiment is to introduce several common pieces of glassware and to
illustrate why one piece of glassware maybe preferred for a particular measurement.

A. Measuring Volume using three different graduated cylinders

1. Examine the beaker and the three graduated cylinders you have. What value do the
smallest marks represent? For example, do the smallest marks (the lines between
the numbered lines) on the scale represent 5mL, 1mL, 0.5mL, 0.2mL or 0.1 mL? In
your notebook, record the value of the smallest marking on each in Table 1.

Table 1. Precision of glassware
Glassware Value of smallest marks
beaker

2. Use the pipet to add 9 mL of water as carefully as possible in the beaker. Record 9
mL in Table 2. You will be estimating 9mL because there is no mark for 9 mL, only
10mL and 5 mL.

3. Pour the water from the beaker into the 100-mL graduated cylinder. Measure the
volume and record the volume to the correct precision in Table 2.

4. Pour the water from the 100-mL graduated cylinder into the 25-graduated cylinder.
Measure and record the volume to the correct precision in Table 2.

5. Pour the water from the 25-mL graduated cylinder into the 10-mL graduated
cylinder. Measure and record the volume to the correct precision in Table 2.

Table 2. Measuring Volume
Measurement + unit
beaker

B. Measuring Temperature using a oC thermometer

1. Measure the room temperature. Fill a beaker with water and let it sit on the counter
for 15 minutes. Place the thermometer in the beaker with water. Measure to the
correct precision and record the temperature once the liquid in the thermometer
stops moving.

2. Measure the temperature of ice water. Add ice to the beaker with water. Place the
thermometer in the beaker with ice water. Measure to the correct precision and
record the temperature once the liquid in the thermometer stops moving.

Table 3. Measuring temperature
Measurement + unit
Room temperature water
Ice water

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C. Measuring length using a ruler

1. Measure to the correct precision and record the length of the line below, using the
metric ruler.

2. Measure and record the length of the same line using inches

Table 4. Measuring length
Measurement + unit
Line 1 (metric)
Line 1 (English)

Post-Lab questions

1. When taking a measurement, how do you determine the last digit in the number you
report?

2. When using a graduated cylinder, the liquid often curves up along the sides of the
container. Where along this curve should you measure the volume?

3. Explain why your measurement might not be identical to the measurements taken
by your lab mates. Assuming all the measurements were taken correctly, what is
the maximum number of digits that should differ between your measurement and

4. When measuring a small volume, such as the volume of a small test tube, which size
graduated cylinder should you use to obtain the most precise measurement.