pp ch 1 and 2 - pbworkschemistry121.pbworks.com/w/file/fetch/104164255/pp ch 1 and 2 6... · • is...

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Karen C. Timberlake

Lecture Presentation

Chapter 1

Chemistry in Our Lives

Chemistry • is the study of composition,

structure, properties, and reactions of matter.

• happens all around you every day.

Antacid tablets undergo a chemical reaction when dropped in water.

What is Chemistry?

Matter is another word for all substances that make up our world.

Matter is defined as anything that has mass and occupies space (volume)

• Antacid tablets are matter.

• Water is matter.

• Glass is matter.

• Air is matter.

Chemistry and Matter

Math Skills Needed For Chemistry

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For any number, we can identify the place value for each of the digits in that number.

The place values for two numbers are listed below:

Key Math Skill Identifying Place Values

A premature baby has a mass of 2518 grams.

A silver coin has a mass of 6.407 grams.

Identifying Place Values

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Equations can be rearranged to solve for an unknown variable.

1. Place all like items on one side.

2. Isolate the variable you need to solve for.

3. Check your answer.

Key Math Skill Solving Equations

Solving Equations

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Solve the following equation for P1.

Study Check

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Solve the following equation for P1.

To solve for P1, divide both sides by V1.

Solution

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People have an average of 1 × 105 hairs on the scalp. Each hair is about 8 × 10−6 m wide.

Key Math Skill Writing Numbers in Scientific Notation

Scientific Notation

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Scientists use scientific notation for two reasons:1. To make it easier to report extremely large or

extremely small measurements2. To report the correct number of significant digits

in a measured or calculated value

We will first focus on reason 1.

1. Scientific Notation

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Rules for writing a number in scientific notation:

Numbers written in scientific notation have two parts:1. A Coefficient 2. A Power of 10

To write 2400 in the correct scientific notation,

• Move the decimal place to the left until there is only 1 non zero digit to the left of the decimal place - the coefficient is 2.4.

• Count the number of places the decimal place was moved – that become the coefficient on the the power of 10, which is 3.

• write the product of the coefficient multiplied by a power of 10.

2.4 × 103

1. Scientific Notation

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Guide to Converting a Number in Standard Notation Into Scientific Notation – Numbers 10 or Greater

Step 1:Move the decimal point on the original number to the left until there is only 1 nonzero digit to the left of the decimal place. This becomes the “coefficient” in scientific notation. Count the number of “number places” the decimal place was moved to the left. This becomes the positive exponent on the power of 10. Step 2: Write the coefficient multiplied by the power of ten, the exponent on the power of 10 is the number of “places” you moved the decimal.

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Numbers 10 or greater

2 400 = 2.4 × 1 000 = 2.4 × 103

3 places Coefficient × Power of 10

Scientific Notation Examples:

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Guide to Converting a Number in Standard Notation Into Scientific Notation – Numbers less than 1

Step 1:Move the decimal point on the original number to the right until there is only 1 nonzero digit to the left of the decimal place. This becomes the “coefficient” in scientific notation. Count the number of “number places” the decimal place was moved to the right. This becomes the negative exponent on the power of 10. Step 2: Write the coefficient multiplied by the power of ten, the exponent on the power of 10 is the number of “places” you moved the decimal.

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0.00086 = = 8.6 × 10−4

4 places Coefficient × Power of 10

Scientific Notation Examples – numbers less than 1

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Example: the diameter of chickenpox virus is 0.000 000 3 m

= 3 × 10−7 m

Measurements Using Scientific Notation

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Write each of the following in correct scientific notation:

A. 64 000

B. 0.021

Study Check

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Karen C. Timberlake

Lecture Presentation

Chapter 2

Chemistry and Measurements

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2.1 Units of Measurement

The metric system is the standard system of measurement used in chemistry.

Learning Goal Write the names and abbreviations for the metric or SI units used in measurements of length, volume, mass, temperature, and time.

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Units of Measurement

Scientists use the metric system of measurement and have adopted a modification of the metric system called the International System of Units as a worldwide standard.

The International System of Units (SI) is an official system of measurement used throughout the world for units of length, volume, mass, temperature, and time.

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Units of Measurement: Metric and SI

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Length: Meter (m), Centimeter (cm)

Length in the metric and SI systems is based on the meter, which is slightly longer than a yard.

1 m = 100 cm 1m = 1.09 yd1 m = 39.4 in. 2.54 cm = 1 in.

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Volume: Liter (L), Milliliter (mL)

Volume is the space occupied by a substance. The SI unit of volume is m3; however, in the metric system, volume is based on the liter, which is slightly larger than a quart.

1 L = 1000 mL1 L = 1.06 qt946 mL = 1 qt Graduated cylinders are used

to measure small volumes.

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Mass: Gram (g), Kilogram (kg)

The mass of an object is a measure of the quantity of material it contains.

1 kg = 1000 g

1 kg = 2.20 lb

454 g = 1 lb

The SI unit of mass, the kilogram (kg), is used for larger masses. The metric unit for mass is the gram (g), which is used for smaller masses.

On an electronic balance, the digital readout gives the mass of a nickel, which is 5.01 g.

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Temperature: Celsius (°C), Kelvin (K)

Temperature tells us how hot or cold something is.

Temperature is measured using

• Celsius (°C) in the metric system.

• Kelvin (K) in the SI system.

Water freezes at 32 °F, or 0 °C.

The Kelvin scale for temperature begins at the lowest possible temperature, 0 K.

A thermometer is used to measure temperature.

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2.2 Measured Numbers and Significant Figures

Length is measured by observing the marked lines at the end of a ruler. The last digit in your measurement is an estimate, obtained by visually dividing the space between the marked lines.

Learning Goal Identify a number as measured or exact; determine the number of significant figures in a measured number.

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Measured Numbers

Measured numbers are the numbers obtained when you measure a quantity such as your height, weight, or temperature.

To write a measured number,

• observe the numerical values of the marked lines.

• estimate the value of the number between the marks.

The estimated number is the final number in your measured number.

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Measured Numbers for Length

The lengths of the objects are measured as

A. 4.5 cm.

B. 4.55 cm.

C. 3.0 cm

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Significant Figures

In a measured number, the significant figures (SFs) are all the digits, including the estimated digit.

Significant figures

• are used to represent the amount of error associated with a measurement.

• are all nonzero digits and zeros between digits.

• are not zeros that act as placeholders before digits.

• are zeros at the end of a decimal number.

Core Chemistry Skill Counting Significant Figures

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Measured Numbers: Significant Figures

A number is a significant figure (SF) if it is/has

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© 2013 Pearson Education, Inc. Chapter 1, Section 1 31

The Atlantic-Pacific Rule For Significant Digits

Imagine your number in the middle of the country

Pacific Atlantic

If a decimal point is present, start counting digits from the Pacific (left) side of the number,

The first sig fig is the first nonzero digit, then any digit after that.

e.g. 0.003100 would have 4 sig figs 31© 2013 Pearson Education, Inc. Chapter 1, Section 1 32

The Atlantic-Pacific Rule For Significant Digits

Imagine your number in the middle of the country

Pacific Atlantic

If the decimal point is absent, start counting digits from the Atlantic (right) side, starting with the first non-zero digit. The first sig fig is the first nonzero digit, then any digit after that

e.g. 31,400 ( 3 sig. figs.)

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General, Organic, and Biological Chemistry: Structures of Life, 5/eKaren C. Timberlake

© 2016 Pearson Education, Inc.

Scientific Notation and Significant Zeros

When one or more zeros in a large number are significant,• they are shown clearly by writing the number in scientific

notation.In this book, we place a decimal point after a significant zero at the end of a number.For example, if only the first zero in the measurement 300 m is significant, the measurement is written as 3.0 × 102 m.



Scientific Notation and Significant Zeros

Zeros at the end of large standard numbers without a decimal point are not significant.

• 400 000 g is written with one SF as 4 × 105 g.

• 850 000 m is written with two SFs as 8.5 × 105 m.

Zeros at the beginning of a decimal number are used as placeholders and are not significant.

• 0.000 4 s is written with one SF as 4 × 10−4 s.

• 0.000 0046 g is written with two SFs as 4.6 × 10−6 g.



Study Check

Identify the significant and nonsignificant zeros in each of the following numbers, and write them in the correct scientific notation.

A. 0.002 650 m

B. 43.026 g

C. 1 044 000 L



Solution

Identify the significant and nonsignificant zeros in each of the following numbers, and write them in the correct scientific notation.A. 0.002 650 m is written as 2.650 × 10−3 m. four SFs

• The zeros preceding the 2 are not significant.• The digits 2, 6, 5 are significant.• The zero in the last decimal place is significant.

B. 43.026 g is written as 4.3026 × 101 g. five SFs• The zeros between nonzero digits or at the end of

decimal numbers are significant.

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Solution

Identify the significant zeros and nonsignificant zeros in each of the following numbers, and write them in the correct scientific notation.C. 1 044 000 L is written as 1.044 × 106 L. four SFs

• The zeros between nonzero digits are significant.• The zeros at end of a number with no decimal point

are not significant.



Exact Numbers

Exact numbers are

• not measured and do not have a limited number of significant figures.

• not used to find the number of significant figures in a calculated answer.

• numbers obtained by counting. 8 cookies

• definitions that compare two units. 6 eggs

• definitions in the same measuring system. 1 qt = 4 cups

1 kg = 1 000 g



Exact Numbers

Examples of exact numbers include the following:



Study Check

Identify the numbers below as measured or exact, and give the number of significant figures in each measured number.

A. 3 coins

B. The diameter of a circle is 7.902 cm.

C. 60 min = 1 h



2.3 Significant Figures in Calculations

A calculator is helpful in working problems and doing calculations faster.

Learning Goal Adjust calculated answers to give the correct number of significant figures.



Rules for Rounding Off

1. If the first digit to be dropped is 4 or less, then it and all the following digits are dropped from the number.

2. If the first digit to be dropped is 5 or greater, then the last retained digit of the number is increased by 1.

Key Math Skill Rounding Off

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Study Check

Write the correct value when 3.1457 g is rounded to each of the following:

A. three significant figures

B. two significant figures



Solution

Write the correct value when 3.1457 g is rounded to each of the following:A. To round 3.1457 to three significant figures,

• drop the final digits, 57.• increase the last remaining digit by 1.The answer is 3.15 g.

B. To round 3.1457 g to two significant figures, • drop the final digits, 457.• do not increase the last number by 1, since the first digit

dropped is 4.The answer is 3.1 g.



Multiplication and Division: Measured Numbers

In multiplication or division, the final answer is written so that it has the same number of significant figures (SFs) as the measurement with the fewest significant figures.

Example 1 Multiply the following measured numbers:

24.66 cm × 0.35 cm = 8.631 (calculator display)

= 8.6 cm2 (two significant figures)

Multiplying four SFs by two SFs gives us an answer with two SFs.

Core Chemistry Skill Using Significant Figures in CalculationsGeneral, Organic, and Biological Chemistry: Structures of Life, 5/eKaren C. Timberlake


Multiplication and Division: Measured Numbers

Example 2 Multiply and divide the following measured numbers:



Adding Significant Zeros

Adding Zeros: When the calculator display contains fewer SFs than needed, add one or more significant zeros to obtain the correct number of significant figures.

Example: Multiply and divide the following measured numbers:



Study Check

Perform the following calculation of measured numbers. Give the answer in the correct number of significant figures.

×

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Solution

Perform the following calculation of measured numbers. Give the answer in the correct number of significant figures.



Measured Numbers: Addition and Subtraction

In addition or subtraction, the final answer is written so that it has the same number of decimal places as the measurement with the fewest decimal places.

Example 1 Add the following measured numbers:

2.012 Thousandths place

61.09 Hundredths place

+ 3.0 Tenths place

66.102 Calculator display

66.1 Answer rounded to the tenths place



Measured Numbers: Addition and Subtraction

Example 2 Subtract the following measured numbers:

65.09 Hundredths place

− 3.0 Tenths place

62.09 Calculator display

62.1 Answer rounded to the tenths place



Study Check

Add the following measured numbers:

82.409 mg

+ 22.0 mg



Solution


82.409 mg

+ 22.0 mg


82.409 mg Thousandths place

Tenths place

104.409 mg Calculator display

104.4 mg Answer rounded to the tenths place



2.4 Prefixes and Equalities

Using a retinal camera, an ophthalmologist photographs the retina of the eye.

Learning Goal Use the numerical values of prefixes to write a metric equality.

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Prefixes

A special feature of the SI as well as the metric system is that a prefix can be placed in front of any unit to increase or decrease its size by some factor of ten.

For example, the prefixes milli and micro are used to make the smaller units.

milligram (mg)

microgram (μg or mcg)

Core Chemistry Skill Using Prefixes



Metric and SI Prefixes

Prefixes That Increase the Size of the Unit



Metric and SI Prefixes

Prefixes That Increase Decrease the Size of the Unit



Prefixes and Equalities

• The relationship of a prefix to a unit can be expressed by replacing the prefix with its numerical value.

• For example, when the prefix kilo in kilometer is replaced with its value of 1000, we find that a kilometer is equal to 1000 meters.

kilometer = 1000 meters (103 m)kiloliter = 1000 liters (103 L)kilogram = 1000 grams (103 g)



Study Check

Fill in the blanks with the correct prefix:A. 1000 m = 1 ___ m

B. 1 × 10−3 g = 1 ___ g

C. 0.01 m = 1 ___ m



Measuring Length

Ophthalmologists measure the diameter of the eye’s retina in centimeters (cm), while a surgeon measures the length of a nerve in millimeters (mm).

Each of the following equalities describes the same length in a different unit.

1 m = 100 cm = 1 × 102 cm1 m = 1000 mm = 1 × 103 mm1 cm = 10 mm = 1 × 101 mm

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Volumes of 1 L or smaller are common in the health sciences. When a liter is divided into 10 equal portions, each portion is called a deciliter (dL).

Examples of some volume equalities include the following:1 L = 10 dL = 1 × 101 dL1 L = 1000 mL = 1 × 103 mL1 dL = 100 mL = 1 × 102 mL

Measuring Volume



Measuring Volume



The Cubic Centimeter

The cubic centimeter (abbreviated as cm3 or cc) is the volume of a cube whose dimensions are 1 cm on each side.

A cubic centimeter has the same volume as a milliliter, and the units are often used interchangeably.

1 cm3 = 1 cc = 1 mL and

1000 cm3 = 1000 mL = 1 L

A plastic intravenous fluid

container contains 1000 mL.



The Cubic Centimeter

A cube measuring 10 cm on each side has a volume of 1000 cm3.

10 cm × 10 cm × 10 cm = 1000 cm3 = 1000 mL = 1 L



Measuring Mass

When you visit the doctor for a physical examination, he or she records your mass in kilograms (kg) and laboratory results in micrograms (μg or mcg).

Examples of equalities between different metric units of mass are as follows:

1 kg = 1000 g = 1 × 103 g

1 g = 1000 mg = 1 × 103 mg

1 g = 100 cg = 1 × 102 cg

1 mg = 1000 μg, 1000 mcg = 1 × 103 μg



Study Check

Identify the larger unit in each of the following:

A. mm or cm

B. kilogram or centigram

C. mL or μL

D. kL or mcL

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2.5 Writing Conversion Factors

In the United States, the contents of many packaged foods are listed in both U.S. and metric units.

Learning Goal Write a conversion factor for two units that describe the same quantity.



Equalities

Equalities

• use two different units to describe the same measured amount.

• are written for relationships between units of the metric system, U.S. units, or between metric and U.S. units.

For example,

1 m = 1000 mm (103 mm)

1 lb = 16 oz

2.20 lb = 1 kg

Core Chemistry Skill Writing Conversion Factors from Equalities



Equalities: Conversion Factors

Any equality can be written as conversion factors.

Conversion Factors for the Equality 60 min = 1 h

Conversion Factors for the Metric Equality 1 m = 100 cm



Equalities: Conversion Factors and SF

The numbers in • any equality between two metric units or between two

U.S. system units are obtained by definition and are, therefore, exact numbers.

• As definitions are exact, they are not used to determine significant figures.

• an equality between metric and U.S. units contains one number obtained by measurement and therefore counts toward the significant figures.

Exception: The equality 1 in. = 2.54 cm has been defined as an exact relationship. Therefore, 2.54 is an exact number.



Some Common Equalities



Metric Conversion Factors

We can write metric conversion factors.

Both are proper conversion factors for the relationship; on is just the inverse of the other.

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Metric–U.S. System Conversion Factors

We can write metric–U.S. system conversion factors.

In the United States, the contents of many packaged foods are listed in both U.S. and metric units.



Study Check

Write conversion factors from the equality for each of the following:A. liters and millilitersB. meters and inchesC. meters and kilometers



Solution

Write conversion factors from the equality for each of the following:

A.

B.

C.

Equalities and Conversion Factors Within a Problem

An equality may also be stated within a problem that applies only to that problem.

The car was traveling at a speed of 85 km/h.

One tablet contains 500 mg of vitamin C.





Equalities stated within dosage problems for medication can also be written as conversion factors.

Keflex (Cephalexin), an antibiotic used for respiratory and ear infections, is available in 250-mg capsules.

Conversion Factors: Dosage Problems Conversion Factors: Percentage, ppm, ppb

A percentage (%) is written as a conversion factor by choosing a unit and expressing the numerical relationship of the parts of this unit to 100 parts of the whole.

A person might have 18% body fat by mass.

To indicate very small ratios, we use parts per million (ppm) and parts per billion (ppb).



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Study Check

Write the equality and its corresponding conversion factors. Identify each number as exact, or give its significant figures in the following statement:

Salmon contains 1.9% omega-3 fatty acids.



Solution

Write the equality and its corresponding conversion factors. Identify each number as exact, or give its significant figures in the following statement:

Salmon contains 1.9% omega-3 fatty acids.

Exact Two SFs



Study Check

Write the equality and conversion factor for each of the following:

A. Meters and centimeters (length)

B. Jewelry that contains 18% gold (percentage)

C. One gallon of gas is $3.40.



Solution

Write the equality and conversion factor for each of the following:

A. Meters and centimeters

B. Jewelry that contains 18% gold

C. One gallon of gas is $3.40.



2.6 Problem Solving Using Unit Conversion (Also called Dimensional Analysis)

Exercising regularlyhelps reduce body fat.

Learning Goal Use conversion factors to change from one unit to another.



Guide to Problem Solving Using Unit Conversion (Dimensional Analysis)

The process of problem solving in chemistry often requires one or more conversion factors to change a given unit to the needed unit.

Problem solving in chemistry requires• identification of the given quantity units.• determination of the units needed.• identification of conversion factors that connect the given

and needed units.

Core Chemistry Skill Using Conversion Factors

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Guide to Problem Solving Using Unit Conversion

Steps for solving problems that contain unit conversions include the following:



Solving Problems Using Unit Conversion

Example: If a person weighs 164 lb, what is the body mass in kilograms?

STEP 1 State the given and needed quantities.

STEP 2 Write a unit plan to convert the given unit to the needed unit.

pounds kilograms



Solving Problems Using Unit Conversion

Example: If a person weighs 164 lb, what is the body mass in kilograms?

STEP 3 State the equalities and conversion factors.

STEP 4 Set up the problem to cancel units and calculate the answer.



Study Check

A rattlesnake is 2.44-m long. How many centimeters long is the snake?



Solution




meters centimeters

ANALYZE GIVEN NEEDTHE PROBLEM 2.44 m centimetersANALYZE GIVEN NEEDTHE PROBLEM 2.44 m centimeters

Metric Factor Metric Factor






Solution

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Using Two or More Conversion Factors

In problem solving,

• two or more conversion factors are often needed to complete the change of units.

• in setting up these problems, one factor follows the other.

• each factor is arranged to cancel the preceding unit until the needed unit is obtained.




Example: A doctor’s order prescribed a dosage of 0.150 mg of Synthroid. If tablets contain 75 mcg of Synthroid, how many tablets are required to provide the prescribed medication?


STEP 2 Write a plan to convert the given unit to the needed unit.

milligrams micrograms

ANALYZE GIVEN NEEDTHE PROBLEM 0.150 mg Synthroid number of tabletsANALYZE GIVEN NEEDTHE PROBLEM 0.150 mg Synthroid number of tablets

Metric Factor Metric Factor

Clinical Factor

Clinical Factor

numberoftablets



Example: A doctor’s order prescribed a dosage of 0.150 mg of Synthroid. If tablets contain 75 mcg (75 µg) of Synthroid, how many tablets are required to provide the prescribed medication?






Study Check

How many minutes are in 1.4 days?



Solution




days hours minutes

ANALYZE GIVEN NEEDTHE PROBLEM 1.4 days minutesANALYZE GIVEN NEEDTHE PROBLEM 1.4 days minutes

Time Factor Time Factor

Time Factor Time Factor






Solution

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Study Check

A red blood cell has a diameter of approximately 10 µm. What is the diameter of the red blood cell in cm?



Solution




micrometers meters centimetersMetric Factor Metric Factor

Metric factorMetric factor

ANALYZE GIVEN NEEDTHE PROBLEM 10 µm cm ANALYZE GIVEN NEEDTHE PROBLEM 10 µm cm




STEP 3 State the equalities and conversion factors.1 µm = 10-6 m 1 cm = 10-2 m

1 µm or 10-6 m 1 cm or 10-2 m

10-6 m 1 µm 10-2 m 1 cm


10 µm x 10-6 m x 1 cm = 1 x 10-3 cm

1µm 10-2 m

Solution



Study Check

If your pace on a treadmill is 65 meters per minute, how many minutes will it take for you to walk a distance of 7.5 kilometers?



Solution




kilometers meters minutesMetric Factor Metric Factor

Speed Factor Speed Factor

ANALYZE GIVEN NEEDTHE PROBLEM 65 meters/min minutes

7.5 kilometers

ANALYZE GIVEN NEEDTHE PROBLEM 65 meters/min minutes

7.5 kilometers






Solution

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2.7 Density

Objects that sink

in water are more dense than water; objects that float are less dense.

Learning Goal Calculate the density of a substance; use the density to calculate the mass or volume of a substance.



Densities of Common Substances



Calculating Density

Density compares the mass of an object to its volume.



Density of Solids

The density of a solid can be determined by dividing the mass of an object by its volume.



Density Using Volume Displacement

The density of the solid zinc object is calculated by dividing its mass by its displaced volume.

To determine its displaced volume, submerge the solid in water so that it displaces water that is equal to its own volume.

Density calculation:

45.0 mL − 35.5 mL = 9.5 mL = 9.5 cm3



Study Check

What is the density (g/cm3) of a 48.0–g sample of a metal if the level of water in a graduated cylinder rises from 25.0 mL to 33.0 mL after the metal is added?

object

33.0 mL25.0 mL

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Solution

What is the density (g/cm3) of a 48.0–g sample of a metal if the level of water in a graduated cylinder rises from 25.0 mL to 33.0 mL after the metal is added?



Problem Solving Using Density

If the volume and the density of a sample are known, the mass in grams of the sample can be calculated by using density as a conversion factor.

Core Chemistry Skill Using Density as a Conversion Factor




Example: John took 2.0 teaspoons (tsp) of cough syrup. If the syrup had a density of 1.20 g/mL and there is 5.0 mL in 1 tsp, what was the mass, in grams, of the cough syrup?


STEP 2 Write a plan to calculate the needed quantity.

teaspoons milliliters grams

ANALYZE GIVEN NEEDTHE PROBLEM 2.0 tsp syrup

density of syrup (1.20 g/mL) grams of syrup

ANALYZE GIVEN NEEDTHE PROBLEM 2.0 tsp syrup

density of syrup (1.20 g/mL) grams of syrup

U.S.−MetricFactor

U.S.−MetricFactor

DensityFactor

DensityFactor



John took 2.0 teaspoons (tsp) of cough syrup. If the syrup had a density of 1.20 g/mL and there is 5.0 mL in 1 tsp, what was the mass, in grams, of the cough syrup?

STEP 3 Write the equalities and their conversion factors, including density.





John took 2.0 teaspoons (tsp) of cough syrup. If the syrup had a density of 1.20 g/mL and there is 5.0 mL in 1 tsp, what was the mass, in grams, of the cough syrup?

STEP 4 Set up the problem to calculate the needed quantity.



Specific Gravity

Specific gravity (sp gr)

• is a relationship between the density of a substance and the density of water.

• is calculated by dividing the density of a sample by the density of water, which is 1.00 g/mL at 4 °C.

• is a unitless quantity.

A substance with a specific gravity of 1.00 has the same numerical value as the density of water (1.00 g/mL).

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Study Check

An unknown liquid has a density of 1.32 g/mL. What is the volume (mL) of a 14.7-g sample of the liquid?



Specific Gravity

Specific gravity (sp gr)

• is a relationship between the density of a substance and the density of water.

• is calculated by dividing the density of a sample by the density of water, which is 1.00 g/mL at 4 °C.

• is a unitless quantity.

A substance with a specific gravity of 1.00 has the same numerical value as the density of water (1.00 g/mL).

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