Holt: Modern Chemistry

Mickey Sarquis, Jerry L. Sarquis

Chapter 2 Measurements and Calculations - all with Video Answers

Educators

Chapter Questions

01:21

Problem 1

How does quantitative information differ from qualitative information?

Ethan Fuhrman

Numerade Educator

01:30

Problem 2

What is a hypothesis?

Simon Kangoun

Numerade Educator

01:20

Problem 3

a. What is a model in the scientific sense?
b. How does a model differ from a theory?

Ethan Fuhrman

Numerade Educator

01:44

Problem 4

Why is it important for a measurement system to have an international standard?

Simon Kangoun

Numerade Educator

01:48

Problem 5

How does a quantity differ from a unit? Use two examples to explain the difference.

Ethan Fuhrman

Numerade Educator

02:53

Problem 6

List the seven SI base units and the quantities they represent.

Simon Kangoun

Numerade Educator

02:17

Problem 7

What is the numerical equivalent of each of the following SI prefixes?

a. kilo-
b. centi-
c. mega-
d. micro-
e. milli-

Ethan Fuhrman

Numerade Educator

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Identify the SI unit that would be most appropriate for expressing the length of the following.
a. width of a gymnasium
b. length of a finger
c. distance between your town and the closest border
of the next state
d. length of a bacterial cell

Ronald Prasad

Numerade Educator

01:51

Problem 9

Identify the SI unit that would be most appropriate for measuring the mass of each of the following
objects.

a. table
b. coin
c. a 250 mL beaker

Ethan Fuhrman

Numerade Educator

00:58

Problem 10

Explain why the second is not defined by the length of the day.

Simon Kangoun

Numerade Educator

01:40

Problem 11

a. What is a derived unit?
b. What is the SI-derived unit for area?

Ethan Fuhrman

Numerade Educator

02:00

Problem 12

a. List two SI-derived units for volume.
b. List two non-SI units for volume, and explain how they relate to the cubic centimeter.

Simon Kangoun

Numerade Educator

01:54

Problem 13

a. Why are the units that are used to express the densities of gases different from those used to
express the densities of solids or liquids?
b. Name two units for density.
c. Why is the temperature at which density is measured usually specified?

Ethan Fuhrman

Numerade Educator

02:35

Problem 14

a. Which of the solids listed in Figure 2.8 will float on water?
b. Which of the liquids will sink in milk?

Simon Kangoun

Numerade Educator

02:15

Problem 15

a. Define conversion factor.
b. Explain how conversion factors are used.

Ethan Fuhrman

Numerade Educator

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Problem 16

What is the volume, in cubic meters, of a rectangular solid that is 0.25 $\mathrm{m}$ long, 6.1 $\mathrm{m}$ wide, and 4.9 $\mathrm{m}$ high?

Ronald Prasad

Numerade Educator

01:22

Problem 17

Find the density of a material, given that a 5.03 $\mathrm{g}$ sample occupies 3.24 $\mathrm{mL}$ . (Hint: See Sample Problem A.)

Ethan Fuhrman

Numerade Educator

01:55

Problem 18

What is the mass of a sample of material that has a volume of 55.1 $\mathrm{cm}^{3}$ and a density of 6.72 $\mathrm{g} / \mathrm{cm}^{3} ?$

Simon Kangoun

Numerade Educator

01:54

Problem 19

A sample of a substance that has a density of 0.824 $\mathrm{g} / \mathrm{mL}$
has a mass of 0.451 $\mathrm{g}$ . Calculate the volume of the
sample.

Ethan Fuhrman

Numerade Educator

02:11

Problem 20

How many grams are in 882$\mu \mathrm{g} ?$ (Hint: See Sample Problem B.)

Simon Kangoun

Numerade Educator

01:46

Problem 21

Calculate the number of milliters in 0.603 $\mathrm{L}$

Ethan Fuhrman

Numerade Educator

03:23

Problem 22

The density of gold is 19.3 $\mathrm{g} / \mathrm{cm}^{3}$ .
a. What is the volume, in cubic centimeters, of a
sample of gold that has a mass of 0.715 $\mathrm{kg}$ ?
b. If this sample of gold is a cube, what is the length of each edge in centimeters?

Simon Kangoun

Numerade Educator

04:40

Problem 23

a. Find the number of kilometers in 92.25 m.
b. Convert the answer in kilometers to centimeters.

Ethan Fuhrman

Numerade Educator

02:28

Problem 24

Compare accuracy and precision.

Simon Kangoun

Numerade Educator

01:22

Problem 25

a. Write the equation that is used to calculate percentage error.
b. Under what condition will percentage error be negative?

Ethan Fuhrman

Numerade Educator

02:08

Problem 26

How is the average for a set of values calculated?

Simon Kangoun

Numerade Educator

01:28

Problem 27

What is meant by a mass measurement expressed in this form: $4.6 \mathrm{g} \pm 0.2 \mathrm{g} ?$

Ethan Fuhrman

Numerade Educator

02:24

Problem 28

Suppose a graduated cylinder were not correctly
calibrated. How would this affect the results of a
measurement? How would it affect the results of a
calculation using this measurement?

Sima Sarker

Numerade Educator

04:03

Problem 29

Round each of the following measurements to the number of significant figures indicated.

a. 67.029 g to three significant figures
b. 0.15 L to one significant figure
c. 52.8005 $\mathrm{mg}$ to five significant figures
d. 3.17497 mol to three significant figures

Ethan Fuhrman

Numerade Educator

02:13

Problem 30

State the rules governing the number of significant figures that result from each of the following
operations.

a. addition and subtraction
b. multiplication and division

Simon Kangoun

Numerade Educator

03:43

Problem 31

What is the general form for writing numbers in scientific notation?

Ethan Fuhrman

Numerade Educator

01:09

Problem 32

a. By using x and y, state the general equation for quantities that are directly proportional.
b. For two directly proportional quantities, what happens to one variable when the other variable
increases?

Simon Kangoun

Numerade Educator

02:07

Problem 33

a. State the general equation for quantities, x and y, that are inversely proportional.
b. For two inversely proportional quantities, what happens to one variable when the other increases?

Ethan Fuhrman

Numerade Educator

01:42

Problem 34

Arrange in the correct order the following four basic steps for finding the solution to a problem: check
your work, analyze, solve, and plan.

Simon Kangoun

Numerade Educator

01:34

Problem 35

A student measures the mass of a sample as 9.67 g. Calculate the percentage error, given that the correct mass is 9.82 g. (Hint: See Sample Problem C.)

Ethan Fuhrman

Numerade Educator

02:48

Problem 36

A handbook gives the density of calcium as 1.54 $\mathrm{g} / \mathrm{cm}^{3}$ .
Based on lab measurements, what is the percentage
error of a density calculation of 1.25 $\mathrm{g} / \mathrm{cm}^{3} ?$

Simon Kangoun

Numerade Educator

01:53

Problem 37

What is the percentage error of a length measurement
of 0.229 $\mathrm{cm}$ if the correct value is 0.225 $\mathrm{cm} ?$

Ethan Fuhrman

Numerade Educator

02:43

Problem 38

How many significant figures are in each of the following measurements? (Hint: See Sample
Problem D.)
a. 0.4004 $\mathrm{mL}$
b. 6000 $\mathrm{g}$
c. 1.00030 $\mathrm{km}$
d. $400 . \mathrm{mm}$

Simon Kangoun

Numerade Educator

01:58

Problem 39

Calculate the sum of 6.078 g and 0.3329 g.

Ethan Fuhrman

Numerade Educator

01:19

Problem 40

Subtract 7.11 $\mathrm{cm}$ from 8.2 $\mathrm{cm} .$ (Hint: See Sample Problem E.)

Simon Kangoun

Numerade Educator

02:06

Problem 41

What is the product of 0.8102 $\mathrm{m}$ and 3.44 $\mathrm{m} ?$

Ethan Fuhrman

Numerade Educator

01:51

Problem 42

Divide 94.20 $\mathrm{g}$ by 3.16722 $\mathrm{mL}$

Simon Kangoun

Numerade Educator

01:41

Problem 43

Write the following numbers in scientific notation.
a. 0.000 673 0
b. 50 000.0
c. 0.000 003 010

Ethan Fuhrman

Numerade Educator

04:01

Problem 44

The following numbers are in scientific notation. Write them in ordinary notation.
a. $7.050 \times 10^{3} \mathrm{g}$
b. $4.00005 \times 10^{7} \mathrm{mg}$
c. $2.3500 \times 10^{4} \mathrm{mL}$

Simon Kangoun

Numerade Educator

02:38

Problem 45

Perform the following operation. Express the answer in scientific notation and with the correct number of
significant figures.
0.002115 $\mathrm{m} \times 0.0000405 \mathrm{m}$

Ethan Fuhrman

Numerade Educator

02:44

Problem 46

A sample of a certain material has a mass of
$2.03 \times 10^{-3}$ g. Calculate the volume of the sample,
given that the density is $9.133 \times 10^{-1} \mathrm{g} / \mathrm{cm}^{3} .$ Use the
four-step method to solve the problem. (Hint: See
Sample Problem F.)

Simon Kangoun

Numerade Educator

02:00

Problem 47

A man finds that he has a mass of 100.6 $\mathrm{kg} .$ He goes
on a diet, and several months later he finds that he
has a mass of 96.4 $\mathrm{kg}$ . Express each number in
scientific notation, and calculate the number of
kilograms the man has lost by dieting.

Ethan Fuhrman

Numerade Educator

03:56

Problem 48

A large office building is $1.07 \times 10^{2} \mathrm{m}$ long, 31 $\mathrm{m}$
wide, and $4.25 \times 10^{2} \mathrm{m}$ high. What is its volume?

Simon Kangoun

Numerade Educator

02:21

Problem 49

An object has a mass of 57.6 $\mathrm{g} .$ Find the object's density, given that its volume is 40.25 $\mathrm{cm}^{3} .$

Ethan Fuhrman

Numerade Educator

03:56

Problem 50

A lab worker measures the mass of some sucrose as 0.947 mg. Convert that quantity to grams and to
kilograms.

Simon Kangoun

Numerade Educator

02:50

Problem 51

A student calculates the density of iron as 6.80 $\mathrm{g} / \mathrm{cm}^{3}$
by using lab data for mass and volume. A handbook
reveals that the correct value is 7.86 $\mathrm{g} / \mathrm{cm}^{3} .$ What is
the percentage error?

Ethan Fuhrman

Numerade Educator

05:00

Problem 52

Find the table of properties for Group 1 elements in the Elements Handbook (Appendix A). Calculate the volume of a single atom of each element listed in the table by using the equation for the volume of a sphere.
$$\frac{4}{3} \pi \cdot r^{3}$$

Simon Kangoun

Numerade Educator

04:20

Problem 53

Use the radius of a sodium atom from the Elements Handbook (Appendix A) to calculate the number of
sodium atoms in a row 5.00 cm long. Assume that each sodium atom touches the ones next to it.

Ethan Fuhrman

Numerade Educator

03:56

Problem 54

a. A block of sodium that has the measurements 3.00 $\mathrm{cm} \times 5.00 \mathrm{cm} \times 5.00 \mathrm{cm}$ has a mass of 75.5 g. Calculate the density of sodium.
b. Compare your calculated density with the value in the properties table for Group 1 elements.
Calculate the percentage error for your density determination.

Simon Kangoun

Numerade Educator

02:55

Problem 55

How does the metric system, which was once a standard for measurement, differ from SI? Why was
it necessary for the United States to change to SI?

Ethan Fuhrman

Numerade Educator

01:00

Problem 56

What are ISO 9000 standards? How do they affect industry on an international level?

Simon Kangoun

Numerade Educator

01:11

Problem 57

Performance Obtain three metal samples from your teacher. Determine the mass and volume of each
sample. Calculate the density of each metal from your measurement data. (Hint: Consider using the water displacement technique to measure the volume of your samples.)

David Collins

Numerade Educator

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Problem 58

Use the data from the Nutrition Facts label below to answer the following questions:

a. Use the data given on the label for grams of fat and calories from fat to construct a conversion factor that has the units calories per gram.
b. Calculate the mass in kilograms for 20 servings of the food.
c. Calculate the mass of protein in micrograms for one serving of the food.
d. What is the correct number of significant figures for the answer in item a? Why?

Susan Hallstrom

Numerade Educator

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Problem 29

Problem 30

Problem 31

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Problem 51

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