© 2014 Pearson Education, Inc. Dr. Pradip Bag Riverside City College Chapter 1 Matter, Measurement, and Problem Solving

© 2014 Pearson Education, Inc.

Dr. Pradip BagRiverside City College

Chapter 1

Matter, Measurement,and Problem Solving


Syllabus - Chemistry 1A (General Chemistry I)

GENERAL INFOCHE-1A-45285: Lecture: Mon/Wed 8:00 – 9:25am (Room M&S 437) CHE-1A-45287: Lecture: Mon/Wed 8:00 – 9:25am (Room M&S 437) Required Textbooks: Lecture: Chemistry A Molecular Approach; Nivaldo J. Tro; 3rd Ed.

Instructor: Dr. Pradip BagContact: [email protected] hours:

IMPORTANT DATES: (Note: exam dates are tentative and may be changed by instructor)Last day to withdraw without a “W“ March 8th

Last day to withdraw from course with a “W” May 15th

Test 1 5th weekTest 2 10th weekTest 3 14th weekFinal Exam Wednesday, June 10th, 8:00 – 10:30am GRADING SCALE AND POINT DISTRIBUTION: 3 Tests (cumulative) 35% 100-90% = AQuiz 10% 89-80% = BFinal Exam (comprehensive) 25% 79-70% = CLaboratory 30% 69–60% = DTotal 100% ≤ 59% = F


COURSE CONTENTIntroductory MaterialDescribe Chemical and Physical properties of matter (including density). Define materials as elements, compounds or mixturesCollect and record measurements using significant figures to communicate accuracy. Use significant figures appropriately in calculations.Atoms and ElementsUse of the Periodic table and defining properties --- atomic number, atomic weight, isotopes, size, electronegativity, ionization energySubatomic particles --- calculation of protons, neutrons and electrons. Relating Atomic spectra to the model for the Bohr atom. Wave mechanical model of atoms, electron configuration and quantum numbersChemical formulae and chemical bondsCalculation of percent composition and empirical and molecular formula. Ionic and covalent bonding (including bond polarity)Nomenclature, formula writing and Lewis dot structures of compounds. Molecular shapes (VSEPR theory) of molecules and polyatomic ions. Applying concepts of Valence Bond Theory and Molecular Orbital TheoryChemical reactions and chemical equationsMole concept, Avogadro’s number and molar mass. Stoichiometry --- calculate limiting reagents, theoretical yield, % yieldReactions in solution --- calculate molarity and titration endpoints. Recognize Patterns for Types of reactions --- acid/base, precipitation, combustion and oxidation/reduction. Combustion Analysis calculations. Net ionic equations- balancing and production from full molecular equations. Thermochemistry calculations--- calorimetry, enthalpy changes, and Hess’s lawGases and their behaviorCalculations using the Ideal gas law and Combined gas law. Gases in chemical reactions – combining stoichiometry and gas lawsMixtures of gases --- partial pressures, Dalton’s law, Henry’s law. Kinetic molecular theory as it applies to gas behavior. Non-ideal behavior of gasesLiquids, solids and phase changesRelating Intermolecular forces, boiling point and vapor pressure. Crystalline solids --- calculations and properties (cubic and hexagonal unit cells). Phase Diagrams and energy for changes in state.SolutionsCalculations involving Concentrations --- molarity, % Solubilities – prediction based upon rules.


Oxy-Hemoglobin, carbaminohemoglobin, and carboxyhemoglobin

Hemoglobin – Metalloprotien

The properties of matter are determined by the properties of molecules and atoms.

Chemistry - understanding the behavior of matter by studying the behavior of atoms and molecules.

Dietary Minerals: Calcium, Phosphorus, Potassium, Sulfur, Sodium, Chlorine, Magnesium etc.Trace Dietary Elements:Iron, Cobalt, Copper, Zinc, Manganese, Molybdenum, Iodine, Bromine, Lithium, Selenium etc.


Periodic Table: Atoms and Molecules

Astatine, Neptunium, Plutonium, Curium, Americium, Berkelium*, Californium*, Einsteinium, Fermium, Mendelevium, Nobelium, Lawrencium*, Dubnium, and Seaborgium*



Scientific Approach

Observation: Collection of data for the characteristics or behaviors of nature.

Hypotheses: Tentative explanation/interpretation of scientific observations.

Laws: Statement that summarizes past observations and predicts future ones

Theory: A model to explain experimental observations / natural behaviors. It is

validated by experiments.

A law summarizes a series of related observations, while

a theory gives the underlying reasons for them.

P 1/V

Boyle’s Law (1662)


Matter• Matter: Anything that occupies space and has mass.• State: Physical forms (solid, liquid, and gas)• Composition: Basic building blocks

States of Matter

CrystallineAmorphous

NaCl


The Classification of Matter by Composition


Separating Mixtures


Physical and Chemical Changes

Physical Change Chemical Change


Facts:Evaporation of rubbing alcoholMaking a metal wiresReactions of NickelDry ice sublimationMatch ignitionBurning of propaneBleaching using peroxideFrost formation


Physical and Chemical Properties

• A physical property• The smell of gasoline is a

physical property.

• Odor, taste, color, appearance, melting point, boiling point, and density are all physical properties.

• A chemical property • The flammability of gasoline, in

contrast, is a chemical property.• Chemical properties include

corrosiveness, acidity, and toxicity.


• Kinetic energy is the energy associated with the motion of an object.

• Potential energy is the energy associated with the position or composition of an object.

• Thermal energy is the energy associated with the temperature of an object.

• Thermal energy is actually a type of kinetic energy because it arises from the motion of the individual atoms or molecules that make up an object.

Energy: A Fundamental Part of Physical and Chemical Change


• Conservation of Energy: It is neither created nor destroyed

• Systems with high potential energy tend to change in a direction that lowers their potential energy, releasing energy into the surroundings.


The Units of Measurement

• Metric system, used in most of the world• English system, used in the United States

• Scientists use the International System of Units (SI, Système International ), which is based on the metric system.


Length, Mass, Time, and Temperaure

• Meter: The distance light travels through a vacuum in a certain period of time, 1/299,792,458 second.

• Mass: The quantity of matter present in a system.• Weight: Measures the gravitational pull• Second: the duration of 9192631770 periods of the radiation

corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom

• Kelvin: unit of temperature, is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water.

1 m = 39.37 in ; 1 yd = 36 in; 1 kg = 2 lb 3 oz;


Match L) length M) mass V) volume

____ A. A bag of tomatoes is 4.6 kg.

____ B. A person is 2.0 m tall.

____ C. A medication contains 0.50 g Aspirin.

____ D. A bottle contains 1.5 L of water.

Which tool(s) would you use to measure:

A. temperature

B. volume

C. time

D. weight


• The Fahrenheit degree is five-ninths the size of a Celsius degree.

• Temperature scale conversion is done with these formulas:


Example 1.2 Converting between Temperature ScalesA sick child has a temperature of 40.00 °C. What is the child’s temperature in a. K and b. °F?

For Practice 1.2Gallium is a solid metal at room temperature but will melt to a liquid in your hand. The melting point of gallium is 85.6 ° F. What is this temperature on (a) the Celsius scale and (b) the Kelvin scale?


SI multiples for second (s)Multipliers Multiples

Value Symbol Name Value Symbol Name

10−1 s ds decisecond 101 s das decasecond

10−2 s cs centisecond 102 s hs hectosecond

10−3 s ms millisecond 103 s ks kilosecond

10−6 s µs microsecond 106 s Ms megasecond

10−9 s ns nanosecond 109 s Gs gigasecond

10−12 s ps picosecond 1012 s Ts terasecond

10−15 s fs femtosecond 1015 s Ps petasecond

10−18 s as attosecond 1018 s Es exasecond

10−21 s zs zeptosecond 1021 s Zs zettasecond

10−24 s ys yoctosecond 1024 s Ys yottasecond

Prefix Multipliers •These multipliers change the value of the unit by the powers of 10 (just like an exponent does in scientific notation). Diameter of Hydrogen atom 1.06x10-

10 m


1. 1000 m = 1 ___ a) mm b) km c) dm

2. 0.001 g = 1 ___ a) mg b) kg c) dg

3. 0.1 L = 1 ___ a) mL b) cL c) dL

4. 0.01 m = 1 ___ a) mm b) cm c) dm

• ? kilometer (km) = 500 meters (m)

• 2.5 meter (m) = ? centimeters (cm)

• 1 centimeter (cm) = ? millimeter (mm)

• 1 nanometer (nm) = 1.0 x 10-9 meter

Learning Check

O—H distance =9.4 x 10-11 m9.4 x 10-9 cm0.094 nm



For Practice 1.3The woman in this example is shocked that the ring is fake and returns it. She buys a new ring that has a mass of 4.53 g and a volume of 0.212 cm3. Is the new ring genuine?

For More Practice 1.3A metal cube has an edge length of 11.4 mm and a mass of 6.67 g. Calculate the density of the metal and use Table 1.4 to determine the likely identity of the metal.

A man receives a platinum ring from his fiancée. Before the wedding, he notices that the ring feels a little light for its size and decides to determine its density. He places the ring on a balance and finds that it has a mass of 3.15 grams. He then finds that the ring displaces 0.233 cm3 of water. Is the ring made of platinum? (Note: The volume of irregularly shaped objects is often measured by the displacement of water. To use this method, the object is placed in water and the change in volume of the water is measured. This increase in the total volume represents the volume of water displaced by the object and is equal to the volume of the object.) 13.5 g/cm3

Example 1.3 Calculating Density


Every digit is certain except the last digit, which is estimated


Example 1.4 Reporting the Correct Number of Digits

Solution4.57 mL.

For Practice 1.4Record the temperature on the thermometer shown at the right to the correct number of digits.

The graduated cylinder shown at the right has markings every 0.1 mL. Report the volume (which is read at the bottom of the meniscus) to the correct number of digits. (Note: The meniscus is the crescent-shaped surface at the top of a column of liquid.)


Significant Figures

• The greater the number of significant figures, the greater the certainty of the measurement.

Significant Figure Rules Examples

1. All nonzero digits are significant 28.03 0.0540

2. Interior zeroes (zeroes between two nonzero digits) are significant.

408 7.0301


Counting Significant FiguresSignificant Figure Rules Examples

3. Leading zeroes (zeroes to the left of the first nonzero digit) are not significant. They only serve to locate the decimal point.

4. Trailing zeroes (zeroes at the end of a number) are categorized as follows:

45.000 3.5600

Trailing zeroes after a decimal point are always significant.

Trailing zeroes before a decimal point (and after a nonzero number) are always significant.

140.00 2500.55

Trailing zeroes before an implied decimal point are ambiguous and should be avoided by using scientific notation.

12001.2 × 103

1.20 × 103

1.200 × 103

Ambiguous2 significant figures3 significant figures4 significant figures

Decimal points are placed after one or more trailing zeroes if the zeroes are to be considered significant.

1200. 4 significant figures


Exact Numbers

• Exact numbers have an unlimited number of significant figures.

• Exact counting of discrete objects • Integral numbers that are part of an equation• Defined quantities

• Some conversion factors are defined quantities, while others are not.


Example 1.5 Determining the Number of Significant Figures in a Number

How many significant figures are in each number?a. 0.04450 m b. 5.0003 kmc. 10 dm = 1 m d. 1.000 × 105 se. 0.00002 mm f. 10,000 m

For Practice 1.5How many significant figures are in each number?a. 554 km b. 7 penniesc. 1.01 × 105 m d. 0.00099 se. 1.4500 km f. 21,000 m


Significant Figure: Rules for Calculations

Multiplication and Division Rule:

• In multiplication or division, the result carries the same number of significant figures as the factor with the fewest significant figures.


Rules for Calculations

Addition and Subtraction Rule:

• In addition or subtraction the result carries the same number of decimal places as the quantity with the fewest decimal places.

It is helpful to draw a line next to the number with the fewest decimal places. This line determines the number of decimal places in the answer.


Rules for Calculations

Rules for Rounding:

• When rounding to the correct number of significant figures,

• round down if the last (or leftmost) digit dropped is four or less;

• round up if the last (or leftmost) digit dropped is five or more.


Rules for Rounding

• Round to two significant figures:

5.37 rounds to 5.4

5.34 rounds to 5.3

5.35 rounds to 5.4

5.349 rounds to 5.3

• Notice in the last example that only the last (or leftmost) digit being dropped determines in which direction to round—ignore all digits to the right of it.


Rounding in Multistep Calculations

• To avoid rounding errors in multistep calculations round only the final answer.

• Do not round intermediate steps. If you write down intermediate answers, keep track of significant figures by underlining the least significant digit.


Example 1.6 Significant Figures in CalculationsPerform each calculation to the correct number of significant figures.a.1.10 × 0.5120 × 4.0015 ÷ 3.4555b.

c.4.562 × 3.99870 ÷ (452.6755 – 452.33)

d.(14.84 × 0.55) – 8.02

Key: 0.652, 4.9, 53, 0.1

For Practice 1.6Perform each calculation to the correct number of significant figures.a. 3.10007 × 9.441 × 0.0301 ÷ 2.31 b.

c. 2.5110 × 21.20 ÷ (44.11 + 1.223) d. (12.01 × 0.3) + 4.811

Key: 0.381, 121.0, 1.174, 8


Precision and Accuracy

• Accuracy refers to how close the measured value is to the actual value.

• Precision refers to how close a series of measurements are to one another or how reproducible they are.



• Consider the results of three students who repeatedly weighed a lead block known to have a true mass of 10.00 g (indicated by the solid horizontal blue line on the graphs).

Student A Student B Student C

Trial 1 10.49 g 9.78 g 10.03 g

Trial 2 9.79 g 9.82 g 9.99 g

Trial 3 9.92 g 9.75 g 10.03 g

Trial 4 10.31 g 9.80 g 9.98 g

Average 10.13 g 9.79 g 10.01 g



• Measurements are said to be• precise if they are consistent with one another. • accurate only if they are close to the actual value.



• The results of student A are both inaccurate (not close to the true value) and imprecise (not consistent with one another).

• Random error is an error that has the equal probability of being too high or too low.

• The results of student B are precise (close to one another in value), but inaccurate.

• Systematic error is an error that tends toward being either too high or too low.

• The results of student C display little systematic error or random error—they are both accurate and precise.


Solving Chemical Problems

• Most chemistry problems you will solve in this course are unit conversion problems.

• Using units as a guide to solving problems is called dimensional analysis.

• Units should always be included in calculations; they are multiplied, divided, and canceled like any other algebraic quantity.


Dimensional Analysis

• A unit equation is a statement of two equivalent quantities, such as

2.54 cm = 1 in.

• A conversion factor is a fractional quantity of a unit equation with the units we are converting from on the bottom and the units we are converting to on the top.



• Most unit conversion problems take the following form:



Units Raised to a Power:• When building conversion factors for units raised

to a power, remember to raise both the number and the unit to the power. For example, to convert from in2 to cm2, we construct the conversion factor as follows:


Procedure For…Solving Unit Conversion Problems

SortGiven: 1.76 ydFind: cm

Strategy

Example 1.7 Unit ConversionConvert 1.76 yards to centimeters.

For Practice 1.7Convert 288 cm to yards.


Procedure For…Solving Unit Conversion Problems

SortBegin by sorting the information in the problem into given and find.Given: 1.8 qtFind: cm3

Conceptual plan

Example 1.8 Unit ConversionConvert 1.8 quarts to cubic centimeters.

For Practice 1.8Convert 9255 cm3 to gallons.


Example 1.9 Unit Conversions Involving Units Raised to a Power

SortSort the information in the problem into given and find.Given: 5.70 LFind: in3

StrategizeWrite a conceptual plan. Begin with the given information and devise a path to the information that you are asked to find. Notice that for cubic units, you must cube the conversion factors.

Conceptual Plan

Calculate the displacement (the total volume of the cylinders through which the pistons move) of a 5.70 L automobile engine in cubic inches.

For Practice 1.9How many cubic centimeters are there in 2.11 yd3?

For More Practice 1.9A vineyard has 145 acres of Chardonnay grapes. A particular soil supplement requires 5.50 grams for every square meter of vineyard. How many kilograms of the soil supplement are required for the entire vineyard? (1 km2 = 247 acres)


Example 1.10 Density as a Conversion Factor

SortBegin by sorting the information in the problem into given and find.Given:

Find: mass in kg

StrategizeDraw the conceptual plan by beginning with the given quantity—in this case the volume in liters (L). The overall goal of this problem is to find the mass. You can convert between volume and mass using density (g/cm 3). However, you must first convert the volume to cm3. Once you have converted the volume to cm3, use the density to convert to g. Finally, convert g to kg.

Conceptual Plan

The mass of fuel in a jet must be calculated before each flight to ensure that the jet is not too heavy to fly. A 747 is fueled with 173,231 L of jet fuel. If the density of the fuel is 0.768 g/cm3, what is the mass of the fuel in kilograms?

For Practice 1.10Backpackers often use canisters of white gas to fuel a cooking stove’s burner. If one canister contains 1.45 L of white gas, and the density of the gas is 0.710 g/cm3, what is the mass of the fuel in kilograms?

For More Practice 1.10A drop of gasoline has a mass of 22 mg and a density of 0.754 g/cm3. What is its volume in cubic centimeters?


Procedure For…Solving Problems Involving Equations

SortBegin by sorting the information in the problem into given and find.Given: V = 0.058 cm3

Find: r in cm

Strategize Write a conceptual plan for the problem. Focus on the equation(s). The conceptual plan shows how the equation takes you from the given quantity (or quantities) to the find quantity. The conceptual plan may have several parts, involving other equations or required conversions. In these examples, you use the geometrical relationships given in the problem statements as well as the definition of density, d = m/V, which you learned in this chapter.

Conceptual plan

Find the radius (r) in centimeters of a spherical water droplet with a volume (V) of 0.058 cm3. For a sphere, V = (4/3) πr3.

Example 1.11 Problems with Equations


Continued


Relationships Used

SolveFollow the conceptual plan. Solve the equation(s) for the find quantity (if it is not already). Gather each of the quantities that must go into the equation in the correct units. (Convert to the correct units if necessary.) Substitute the numerical values and their units into the equation(s) and calculate the answer.

Solution

Round the answer to the correct number of significant figures.


Continued


CheckCheck your answer. Are the units correct? Does the answer make sense?

The units (cm) are correct and the magnitude makes sense.

For Practice 1.11Find the radius (r) of an aluminum cylinder that is 2.00 cm long and has a mass of 12.4 g. For a cylinder, V = πr2l.


Procedure For…Solving Problems Involving Equations

SortBegin by sorting the information in the problem into given and find.Given:

Find: d in g/cm3

Strategize Write a conceptual plan for the problem. Focus on the equation(s). The conceptual plan shows how the equation takes you from the given quantity (or quantities) to the find quantity. The conceptual plan may have several parts, involving other equations or required conversions. In these examples, you use the geometrical relationships given in the problem statements as well as the definition of density, d = m/V, which you learned in this chapter.

Find the density (in g/cm3) of a metal cylinder with a mass (m) of 8.3 g, a length (l) of 1.94 cm, and a radius (r) of 0.55 cm. For a cylinder, V = πr2l.



Continued


Conceptual plan

Relationships Used

SolveFollow the conceptual plan. Solve the equation(s) for the find quantity (if it is not already). Gather each of the quantities that must go into the equation in the correct units. (Convert to the correct units if necessary.) Substitute the numerical values and their units into the equation(s) and calculate the answer.


Solution

Round the answer to the correct number of significant figures.

CheckCheck your answer. Are the units correct? Does the answer make sense?

The units (g/cm3) are correct. The magnitude of the answer seems correct for one of the lighter metals (see Table 1.4).

For Practice 1.12Find the density, in g/cm3, of a metal cube with a mass of 50.3 g and an edge length (l) of 2.65 cm. For a cube, V = l3.

Continued


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© 2014 Pearson Education, Inc. Dr. Pradip Bag Riverside City College Chapter 1 Matter, Measurement, and Problem Solving