Chapter 1 Chemistry and Measurement PDF

Chapter 1 Chemistry and Measurement  Chemistry The study of the composition and structure of materials and of the changes that materials undergo. Copyright © Cengage Learning. All rights reserved.  Chemistry: A Science for the 21st Century Health and Medicine Sanitation systems S...

Chapter 1 Chemistry and Measurement  Chemistry The study of the composition and structure of materials and of the changes that materials undergo. Copyright © Cengage Learning. All rights reserved.  Chemistry: A Science for the 21st Century Health and Medicine Sanitation systems Surgery with anesthesia Vaccines and antibiotics Gene therapy Energy and the Environment Fossil fuels Solar energy Nuclear energy  Chemistry: A Science for the 21st Century Materials and Technology Polymers, ceramics, liquid crystals Room-temperature superconductors? Molecular computing? Food and Agriculture Genetically modified crops “Natural” pesticides Specialized fertilizers The Study of Chemistry Macroscopic Microscopic 5 The scientific method is a systematic approach to research A hypothesis is a tentative explanation for a set of observations tested modified 6 A law is a concise statement of a relationship between phenomena that is always the same under the same conditions. Force = mass x acceleration A theory is a unifying principle that explains a body of facts and/or those laws that are based on them. Atomic Theory 7  Scientific Method Experiments Results Hypothesis Copyright © Cengage Learning. All rights reserved. 1|8 Hypothesis A tentative explanation of some regularity of nature. Theory A tested explanation of a basic natural phenomenon. Copyright © Cengage Learning. All rights reserved. 1|9 Law A concise statement or mathematical equation about a fundamental relationship or regularity of nature. Copyright © Cengage Learning. All rights reserved. 1 | 10 Experiment An observation of natural phenomena carried out in a controlled manner so that the results can be duplicated and rational conclusions obtained. Copyright © Cengage Learning. All rights reserved. 1 | 11 Chemistry In Action: Primordial Helium and the Big Bang Theory In 1940 George Gamow hypothesized that the universe began with a gigantic explosion or big bang. Experimental Support expanding universe cosmic background radiation primordial helium 12 Chemistry is the study of matter and the changes it undergoes Matter is anything that occupies space and has mass. A substance is a form of matter that has a definite composition and distinct properties. liquid nitrogen gold ingots silicon crystals 13 Matter Whatever occupies space and can be perceived by our senses. Mass The quantity of matter in a material. Copyright © Cengage Learning. All rights reserved. 1 | 14 Law of Conservation of Mass The total mass remains constant during a chemical change (chemical reaction). Copyright © Cengage Learning. All rights reserved. 1 | 15  Aluminum powder burns in oxygen to produce a substance called ? aluminum oxide. A sample of 2.00 grams of aluminum is burned in oxygen and produces 3.78 grams of aluminum oxide. How many grams of oxygen were used in this reaction? aluminum + oxygen = aluminum oxide 2.00 g + oxygen = 3.78 g oxygen = 1.78 g Copyright © Cengage Learning. All rights reserved. 1 | 16 States of Matter Solid: characterized by rigidity; fixed volume and fixed shape. Liquid: relatively incompressible fluid; fixed volume, no fixed shape. Gas: compressible fluid; no fixed volume, no fixed shape. Copyright © Cengage Learning. All rights reserved. 1 | 17 Copyright © Cengage Learning. All rights reserved. 1 | 18 Physical Change A change in the form of matter but not in its chemical identity. For example: Melting Dissolving Copyright © Cengage Learning. All rights reserved. 1 | 19 Chemical Change = Chemical Reaction A change in which one or more kinds of matter are transformed into a new kind of matter or several new kinds of matter. For example: Rusting Burning Copyright © Cengage Learning. All rights reserved. 1 | 20 Physical Property A characteristic that can be observed for a material without changing its chemical identity. For example: Physical state Boiling point Color Copyright © Cengage Learning. All rights reserved. 1 | 21 Chemical Property A characteristic of a material involving its chemical change. For example: Ability to react with oxygen Ability to react with fluorine Copyright © Cengage Learning. All rights reserved. 1 | 22 Substance A kind of matter that cannot be separated into other kinds of matter by any physical process such as distillation or sublimation. Copyright © Cengage Learning. All rights reserved. 1 | 23  Potassium is a soft, silvery-colored metal that melts at 64°C. It reacts ? vigorously with water, with oxygen, and with chlorine. Identify all of the physical properties and chemical properties given in this description. Physical Property Chemical Property Soft Reacts with water Silvery-colored Reacts with oxygen Melting point (64°C) Reacts with chlorine Copyright © Cengage Learning. All rights reserved. 1 | 24 Element A substance that cannot be decomposed into simpler substances by any chemical reaction. For example: Hydrogen Carbon Oxygen Copyright © Cengage Learning. All rights reserved. 1 | 25 Compound A substance composed of two or more elements chemically combined. For example: Water (H2O) Carbon dioxide (CO2) Copyright © Cengage Learning. All rights reserved. 1 | 26 Mixture A material that can be separated by physical means into two or more substances For example: Italian salad dressing Saltwater Copyright © Cengage Learning. All rights reserved. 1 | 27 Heterogeneous Mixture A mixture that consists of physically distinct parts, each with different properties. For example: Salt and iron filings Oil and vinegar Phase One of several different homogeneous materials present in the portion of matter under study. Copyright © Cengage Learning. All rights reserved. 1 | 28 Homogenous Mixture A mixture that is uniform in its properties; also called a solution. For example: Saltwater Air Copyright © Cengage Learning. All rights reserved. 1 | 29 A mixture is a combination of two or more substances in which the substances retain their distinct identities. 1. Homogenous mixture – composition of the mixture is the same throughout. soft drink, milk, solder 2. Heterogeneous mixture – composition is not uniform throughout. cement, iron filings in sand 30 Classification of Matter © 2012 Pearson Education, Inc. Classification of Matter © 2012 Pearson Education, Inc. Classification of Matter © 2012 Pearson Education, Inc. Classification of Matter © 2012 Pearson Education, Inc. Classification of Matter © 2012 Pearson Education, Inc. Classification of Matter © 2012 Pearson Education, Inc. Classification of Matter © 2012 Pearson Education, Inc. Classification of Matter © 2012 Pearson Education, Inc. Classification of Matter Matter And © 2012 Pearson Education, Inc. Measurement Classification of Matter Matter And © 2012 Pearson Education, Inc. Measurement Copyright © Cengage Learning. All rights reserved. 1 | 41  Matter can be represented as being composed of individual units. For ? example, the smallest individual unit of matter can be represented as a single circle, and chemical combinations of these units of matter as connected circles, with each element represented by a different color. Using this model, label each figure on the next slide as an element, a compound, or a mixture. Copyright © Cengage Learning. All rights reserved. 1 | 42 A. Element B. Compound (made of two elements) C. Mixture of two elements Copyright © Cengage Learning. All rights reserved. 1 | 43 Measurement The comparison of a physical quantity with a fixed standard of measurement—a unit. For example: Centimeter Kilogram Copyright © Cengage Learning. All rights reserved. 1 | 44 Precision The closeness of the set of values obtained from repeated measurement of the same quantity. Accuracy The closeness of a single measurement to its true value. Copyright © Cengage Learning. All rights reserved. 1 | 45  Imagine that you shot five arrows at ? each of the targets depicted on the next slide. Each “x” represents one arrow. Choose the best description for each target. Copyright © Cengage Learning. All rights reserved. 1 | 46  X X X X X XXX XX XXX XX X A B C 1. Poor accuracy and good precision 2. Poor accuracy and poor precision 3. Good accuracy and good precision 4. Good accuracy and poor precision A: 1 B: 4 C: 3 Copyright © Cengage Learning. All rights reserved. 1 | 47 Significant Figures Those digits in a measured number (or in the result of a calculation with measured numbers) that include all certain digits plus a final digit having some uncertainty. Copyright © Cengage Learning. All rights reserved. 1 | 48  What is the length of the nail to the ? correct number of significant figures? 5.7 cm (The tenths place is estimated) Copyright © Cengage Learning. All rights reserved. 1 | 49 Number of Significant Figures The number of digits reported for the value of a measured or calculated quantity, indicating the precision of the value. Copyright © Cengage Learning. All rights reserved. 1 | 50 Number of Significant Figures 1. All nonzero digits are significant. 2. Zeros between nonzero digits are significant. 3. Leading zeros are not significant. 4. Terminal zeros are significant if they are to the right of the decimal point. 5. Terminal zeros in a number without a specific decimal point may or may not be significant. Copyright © Cengage Learning. All rights reserved. 1 | 51 Significant Figures in Calculations Multiplication and Division Your answer should have the same number of significant figures as are in the measurement with the least number of significant figures. Copyright © Cengage Learning. All rights reserved. 1 | 52 Addition and Subtraction Your answer should have the same number of decimal places as are in the measurement with the least number of decimal places. Copyright © Cengage Learning. All rights reserved. 1 | 53 Exact Number A counted number or defined number. For example: The number of students in the front row 1 inch is defined as 2.54 centimeters Copyright © Cengage Learning. All rights reserved. 1 | 54 Rounding The procedure of dropping nonsignificant digits and adjusting the last digit reported in the final result of a calculation. Copyright © Cengage Learning. All rights reserved. 1 | 55 Rounding Procedure 1. Look at the leftmost digit to be dropped. 2. If this digit is 5 or greater: Add 1 to the last digit to be retained Drop all digits farther to the right 3. If this digit is less than 5: Drop all digits farther to the right Copyright © Cengage Learning. All rights reserved. 1 | 56 For example: 1.2151 rounded to three significant figures is 1.22 1.2143 rounded to three significant figures is 1.21 Copyright © Cengage Learning. All rights reserved. 1 | 57  Perform the following calculation and round your answer to the correct ? number of significant figures: 6.8914 1.289  7.28 Calculator answer: 0.734383925 The answer should be rounded to three significant figures: 0.734 Copyright © Cengage Learning. All rights reserved. 1 | 58  Perform the following calculation and round your answer to the correct ? number of significant figures: 0.453 − 1.59 Calculator answer: -1.13700000 The answer should be rounded to two decimal places: -1.14 Copyright © Cengage Learning. All rights reserved. 1 | 59  Perform the following calculation and round your answer to the correct ? number of significant figures: 0.456 − 0.421 Calculator answer: 0.03500000 The answer should be rounded to three decimal places: 0.035 Copyright © Cengage Learning. All rights reserved. 1 | 60  Perform the following calculation and round your answer to the correct ? number of significant figures: 92.35(0.456 − 0.421) Calculator answer: 3.23225000 The answer should be rounded to two significant figures because 0.456 – 0.421 = 0.035: 3.2 Copyright © Cengage Learning. All rights reserved. 1 | 61 SI Units An international system of units made up of a particular choice of metric units. Base Units The seven metric units from which all other units can be derived. Copyright © Cengage Learning. All rights reserved. 1 | 62 Copyright © Cengage Learning. All rights reserved. 1 | 63 Copyright © Cengage Learning. All rights reserved. 1 | 64 Scientific Notation The representation of a number in the form A × 10n 1 ≤ A < 10 where n is an integer Every digit included in A is significant. Copyright © Cengage Learning. All rights reserved. 1 | 65  Write the following numbers in scientific notation: ? 0.000653 350,000 0.02700 6.53 × 10-4 3.5 × 105 2.700 × 10-2 Copyright © Cengage Learning. All rights reserved. 1 | 66 Scientific Notation and Metric Prefixes Because each of the metric prefixes has an equivalent power of 10, the prefix may be substituted for the power of 10. For example: 7.9 × 10-6 s 10-6 = micro, m 7.9 × 10-6 s = 7.9 ms Copyright © Cengage Learning. All rights reserved. 1 | 67  Write the following measurements without scientific notation using the ? appropriate SI prefix: 4.851 × 10-9 g 3.16 × 10-2 m 8.93 × 10-12 s 4.851 ng 3.16 cm 8.93 ps Copyright © Cengage Learning. All rights reserved. 1 | 68  Using scientific notation, make the following conversions: ? 6.20 km to m 2.54 cm to m 1.98 ns to s 5.23 mg to g 6.20 × 103 m 2.54 × 10-2 m 1.98 × 10-9 s 5.23 × 10-6 g Copyright © Cengage Learning. All rights reserved. 1 | 69 Temperature A measure of “hotness” Heat flows from an area of higher temperature to an area of lower temperature. Temperature Units Celsius, °C Fahrenheit, °F Kelvin, K Copyright © Cengage Learning. All rights reserved. 1 | 70 1 | 71 Converting Between Temperature Units Finding Kelvin temperature from Celsius temperature.  1K  tK =  tC   + 273.15 K  1C  Finding Fahrenheit temperature from Celsius temperature.  9F  tF =  tC   + 32 ο F  5C  Copyright © Cengage Learning. All rights reserved. 1 | 72 Converting Between Temperature Units Finding Celsius temperature from Fahrenheit temperature. 5C t C = ( tF − 32F ) 9F Finding Celsius temperature from Kelvin temperature. 1C t C = (t K − 273.15 K ) 1K Copyright © Cengage Learning. All rights reserved. 1 | 73  In winter, the average low temperature in interior Alaska is ? -30.°F (two significant figures). What is this temperature in degrees Celsius and in kelvins? 5C tC = ( tF − 32F ) 9F 5C tC = ( −30.F − 32F ) 9F 5C tC = ( − 62F ) 9F tC = −34.4444444C tC = − 34C Copyright © Cengage Learning. All rights reserved. 1 | 74   1K  tK =  tC   + 273.15 K  1C   1K  tK =  −34C   + 273.15 K  1C  tK = −34 K + 273.15 K tK = 239.15 K t K = 239 K Copyright © Cengage Learning. All rights reserved. 1 | 75 Derived Units Combinations of fundamental units. For example: distance m Speed = = time s Volume = length  width  height = m 3 Copyright © Cengage Learning. All rights reserved. 1 | 76 Quantity Definition of Quantity SI Unit Area length × length m2 Volume length × length × length m3 Density mass per unit volume kg/m3 Speed distance per unit time m/s Acceleration change in speed per unit time m/s2 Copyright © Cengage Learning. All rights reserved. 1 | 77  Quantity Definition of Quantity SI Unit Force mass × acceleration kg  m/s2 = N (newton) Pressure force per unit area kg/m  s2 = Pa (pascal) Energy force × distance kg  m2/s2 = J (joule) Copyright © Cengage Learning. All rights reserved. 1 | 78 Density m Mass per unit volume d= V Common units solids g/cm3 liquids g/mL gases g/L Copyright © Cengage Learning. All rights reserved. 1 | 79  Oil of wintergreen is a colorless liquid ? used as a flavoring. A 28.1-g sample of oil of wintergreen has a volume of 23.7 mL. What is the density of oil of wintergreen? m = 28.1 g m d = V = 23.7 mL V 28.1 g d = 23.7 mL g d = 1.18565491 mL g d = 1.19 mL Copyright © Cengage Learning. All rights reserved. 1 | 80  A sample of gasoline has a density of 0.718 g/mL. What is the volume of ? 454 g of gasoline? m = 454 g m m g d= V= d = 0.718 V d mL 454 g V= g 0.718 mL V = 632.311978 mL V = 632 mL Copyright © Cengage Learning. All rights reserved. 1 | 81 Units and Dimensional Analysis (Factor-Label Method) A method of calculations in which one carries along the units for quantities. Conversion Factor A factor equal to 1 that converts a quantity expressed in one unit to a quantity expressed in another unit. Copyright © Cengage Learning. All rights reserved. 1 | 82  A sample of sodium metal is burned in chlorine gas, producing 573 mg of ? sodium chloride. How many grams and kilograms is this? 1 mg = 10 −3 g and 1 kg = 10 3 g −3 10 g 1 kg 573 mg  0.573 g  3 1 mg 10 g −3 573  10 g −3 0.573  10 kg 0.573 g 5.73  10 −4 kg Copyright © Cengage Learning. All rights reserved. 1 | 83  An experiment calls for 54.3 mL of ? ethanol. What is this volume in cubic meters? 1 mL = 1 cm 3 (1 cm) = 10 m 3 ( −2 ) 3 −6 1 mL = 1 cm = 10 m 3 3 10 −6 m3 54.3 mL  1 mL 54.3  10 −6 m 3 5.43  10−5 m3 Copyright © Cengage Learning. All rights reserved. 1 | 84  The dimensions of Noah’s ark were reported as 3.0 × 102 cubits by 5.0 ? × 101 cubits. Express this size in units of feet and meters. (1 cubit = 1.5 ft) 1 cubit = 1.5 ft 3 ft = 1 yd 1 yd = 0.9144 m (exact) 1.5 ft 1.5 ft 3.0  10 cubits  2 5.0  10 cubits  1 1 cubit 1 cubit 4.5000000  10 2 ft 7.5000000  101 ft 4.5  10 2 ft by 7.5  101 ft = 75 ft Copyright © Cengage Learning. All rights reserved. 1 | 85  1 cubit = 1.5 ft 3 ft = 1 yd 1 yd = 0.9144 m (exact) 4.5  10 ft 2 by 7.5  10 ft = 75 ft 1 1 yd 0.9144 m 1 yd 0.9144 m 4.5  10 ft  2  75 ft   3 ft 1 yd 3 ft 1 yd 1.37160000  10 2 m 22.8600000 m 1.4  10 2 m by 23 m Copyright © Cengage Learning. All rights reserved. 1 | 86  How many significant figures are in ? each of the following measurements? a. 310.0 kg b. 0.224800 m c. 0.05930 kg d. 4.380 × 10−8 m e. 3.100 s f. 91,000 a. 4 significant figures d. 4 significant figures b. 6 significant figures e. 4 significant figures c. 4 significant figures f. 2 significant figures Copyright © Cengage Learning. All rights reserved. 1 | 87