Name
Period
MEASUREMENT OF
MASS AND DENSITY
Mass refers to the quantity of matter composing an object. To find the
mass of an object, we usually compare its mass with the mass of objects
of known mass. You will use a centigram balance to determine mass.
Mass density, p (rho), is mass per unit volume. To determine the mass
density of a material, the mass of a sample of the material is divided
by its volume.
Date
#
liP Lab 1
Equipment
graduated cylinder
centigram balance
string
metric ruler
wood blocks
box of steel paper clips
solid object of irregular
shape or a hooked weight
of known composition
Objectives
During this investigation you will
become familiar with the methods used to measure mass and density.
practice the use of significant digits.
Proced ure
A. Mass of One Paper Clip
1. Inspect your centigram balance. Make sure that all riders are on zero.
Gently touch a platform to make the balance oscillate. The pointer
should swing about the same distance on either side of the center mark
of the scale. If it does not, adjust the movable nut until it does.
2. Place one paper clip on the balance and measure its mass to the
nearest hundredth of a gram (0.01 g). Repeat this procedure twice,
using a different paper clip from the same box each time. Record your
values for the mass of each of the three paper clips in Table 2-1.
Calculate and record the average of your three measurements to the
nearest hundredth of a gram in Table 2-1.
3. Now place 10 paper clips on the balance and measure their total mass.
Calculate the average mass of one paper clip. Record all the information to the nearest hundredth of a gram in Table 2-2.
4. Repeat Step 3, increasing the number of clips on the balance by groups'
of 10 until you have a total of 50 clips on the balance. Record the
data in Table 2-2.
B. Density
1. Measure and record the mass of the empty graduated cylinder. Add
water until the cylinder is half full. Measure the mass of the cylinder
plus water. From this information, calculate the mass of the water
only. Record this value in Table 2-3.
2. Observe the level of the water in the graduated cylinder. To avoid
introducing an error due to parallax, the scale on the cylinder should
be read straight on at the water level (Figure 2-1). Estimate the volume of the water to the nearest tenth of a cubic centimeter (0.1 cm3).
Record this in Table 2-3. Calculate the density of water.
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Meniscus
3. Tie as many paper clips to a piece of string as will fit easily into the
graduated cylinder half full of water. Lower the clips into the water
until they are completely immersed. Dislodge any air bubbles that remain attached to the paper clips by gently shaking the string. Read
the new water level in the cylinder (Figure 2-1). Count the number
clips you used. Record all data in Table 2-4.
4. Determine the total volume of the clips tied to the string. From the
total volume of the clips and the total number of clips tied to the string,
calculate the volume of a single paper clip. Enter this value in Table
of
2-4.
Figure 2-1.
Hold or place the
cylinder so that the liquid is at eye
level. Read the lower portion of the
curved surface (meniscus).
5. Use the average mass of a single clip as determined in Table 2-2 (for
50 clips) as the mass of the clip. Calculate the density of one paper
clip and record this information
in Table 2-4.
6. Measure the length, width, and height of a wood block in centimeters
and calculate its volume. Using the centigram balance, measure the
mass of the block. Enter your measurements in Table 2-5. Calculate
and record the density of the wood.
7. Using the graduated cylinder half full of water, measure the volume
of the solid object of irregular shape just as you measured the volume
of the paper clips in Step
3. Using the balance, measure the mass
of the object. Enter these values in Table 2-6. Calculate and record
the density of the solid.
Data and Calculations
Table2-1
Data
Mass (g)
Trial
First clip
Second clip
Third clip
Average
mass of one paper clip
Table 2-2
Data
Number of
clips
10
20
30
40
50
10
Total mass
(g)
Calculations
Average mass of
one paper clip
Name
Date
Period
Table 2-3
Data
Mass of empty cylinder
Mass of cylinder and water
Volume of water
Calculations
Mass of water
~nj;if<.t
~of
water
Table 2-4
Data
Volume of water (Table 2-3)
Volume of water and clips
Number of clips
Mass of 1 clip (Table 2-2)
Calculations
Total volume of clips
Volume of 1 clip
Density of 1 clip
Table 2-5
Data
Length of block
Width of block
Height of block
Mass of block
Calculations
Volume of block
Density of block
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Table 2-6
Data
Volume of water
Volume of water and object
Mass of object
Calculations
Volume of object
Density of object
Interpreta tion
1.
How well does your average of the measurements of the mass of individual clips in Table 2-1 compare with the average mass of the clips
shown in Table 2-2? Which measurement do you think most closely
approximates the mass of a paper clip? Why?
2. From Table 2-2, what can you assume about the masses of the clips?
3. In Table 2-3, compare your calculated values for density with the
currently accepted values. Explain any differences.
4. Look up the density of steel in a handbook. Compare the published
value with the density of a paper clip that you determined in Step5
of the Procedure. Explain any differences.
CLICK HERE TO SUBMIT
5. A full box of paper clips is supposed to contain 100 clips. Remove
the clips from the box and put all of the clips on.the balance. Measure
their mass. Using your average value for a single clip, determine the
number of clips that were in the box. Check your answer by actually
counting the clips.
6. Predict the mass of 25,35, and 70 paper clips. Record below. Verify
your predictions by actual measurements.
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