CHEM101 General Chemistry I Fall 2024-2025 PDF

[email protected] Textbook Chemistry, The Central Science, 15th edition, By Theodore L. Brown, H. Eugene LeMay, Jr., Bruce E. Bursten, Catherine, J. Murphy, Patrick M. Woodward, Matthew W. Stoltzfus, Pearson Press, USA (9781292407586-Mastering Chemistry Brown Chemistry GE 15e) Chemistry...

[email protected] Textbook Chemistry, The Central Science, 15th edition, By Theodore L. Brown, H. Eugene LeMay, Jr., Bruce E. Bursten, Catherine, J. Murphy, Patrick M. Woodward, Matthew W. Stoltzfus, Pearson Press, USA (9781292407586-Mastering Chemistry Brown Chemistry GE 15e) Chemistry Chemistry is the study of matter, its properties, and the changes it undergoes. Chemistry is central to our fundamental understanding of many science-related fields. Matter Matter is anything that has mass and takes up space. Matter Matter is anything that has mass and takes up space. States of Matter Solid Liquid Gas Fixed Volume Fixed Volume Volume of container Fixed Shape Shape of container Shape of container 5 Classification of Matter – Homogeneous Based on Composition mixture – Heterogeneous mixture – Element – Compound By following this scheme, you can determine how to classify any type of matter.  Classifications of Matter Another scheme, depending on methods of separation & composition. Matter separated by physical means? No: Yes: Pure Substance Mixture decomposed by chemical processes? uniform throughout? Yes: No: No: Yes: Element Compound Homogeneous Heterogeneous Mixture Mixture Elements An element is a pure substance that cannot be separated into simpler substances by physical or chemical means.. 118 elements have been identified 92 elements occur naturally on Earth: gold, aluminum, lead, oxygen, carbon, mercury, sulfur... 26 elements have been created by scientist: americium, seaborgium... Every element is unique. Elements Chemists usually represent elements as symbols. Every element has its own unique symbol. Symbols are one or two letters; the first is always capitalized: For some elements the symbol is simply the first letter of the element’s name. Hydrogen = H Carbon = C Oxygen = O Symbols for other elements use the first letter plus one other letter of the element’s name. The first letter is capitalized and the second letter is not. Aluminum = Al Nickel= Ni Arsenic= As Some elements have symbols referring to the element’s name in Latin. Gold = Au (Aurum) Silver = Ag (Argentum) Some Common Elements & Their Symbols Media Title Earth's crust composition Website NameEncyclopædia Britannica https://www.britannica.com/science/silicon#/media/1/544301/250439  Elemental Composition of Human Body The most abundant element by mass is oxygen, from water. Youst / Getty Images Periodic table organizes elements according to their physical and chemical properties. Emeka Udenze (https://commons.wikimedia.org/wiki/File:Periodic_Table-1.png), „Periodic Table-1“, https://creativecommons.org/licenses/by-sa/4.0/legalcode Elements & Atoms An element is a pure substance which can not be decomposed to simpler substances. But what is an element made of? Atoms are the basic building blocks of matter that make up everyday objects. An atom is the smallest particle of an element that has the properties of that element and can enter into a chemical combination.  Elements & Atoms An element is a pure substance made up of a unique kind of atom. These atoms have distinct properties. Copper element is Carbon element is Helium element is made up of copper made up of carbon made up of helium atoms. atoms. atoms. Photo credit (left): © 2007 Jupiterimages Corporation Photo credit (centre): © 2007 Jupiterimages Corporation Photo credit (right): © 2007 Jupiterimages Corporation  Classifications of Matter Matter separated by physical means? No: Yes: Pure Substance Mixture decomposed by chemical processes? uniform throughout? Yes: No: No: Yes: Element Compound Homogeneous Heterogeneous Mixture Mixture If atoms of different elements combine with each other. Compounds A compound is a substance made of atoms from two or more different elements that are chemically united. A compound is a substance which can be decomposed to simpler substances. Compounds can only be separated into their pure components (elements) by chemical means. Oxygen atom Hydrogen atom Carbon atom Glucose C6H12O6 Balls of different colors are used to Water Carbon dioxide represent atoms of H2O CO2 different elements. Compounds & Chemical Formulas Compounds are composed of atoms of two or more elements chemically united in fixed proportions, have a specific ratio of elements. The subscript to the right of an element symbol tells the number of atoms of that element in one molecule (or formula unit) of the substance. for example, water is always made up of two atoms of hydrogen and one atom of oxygen. Its chemical formula can be expressed as H2O. (The hydrogen atoms are bonded to the oxygen.) Oxygen atom Hydrogen atom Carbon atom Glucose C6H12O6 Water Carbon dioxide H2O CO2  Compounds & Composition The Law of Constant Composition (Law of Definite Proportions) – Joseph Proust – 1799: All samples of a compound have the same composition – the same proportion by mass of the constituent elements. -> The numbers of atoms of the elements in a given compound must always exist in the same ratio. Water H2O Carbon dioxide CO2  Compounds & Chemical Formulas Compounds are composed of atoms of two or more elements chemically united in fixed proportions, have a specific ratio of elements. The subscript to the right of an element symbol tells the number of atoms of that element in one molecule (or formula unit) of the substance. Sodium carbonate Sodium bicarbonate Na2CO3 NaHCO3 Chemicalinterest (https://commons.wikimedia.org/wiki/File:Sodium_carbonate.JPG), „Sodium carbonate“, marked as public domain, more details on Wikimedia Commons: https://commons.wikimedia.org/wiki/Template:PD-self Kapitánka Nemo (https://commons.wikimedia.org/wiki/File:Hydrogenu hličitan_sodný_2.jpg), „Hydrogenuhličitan sodný 2“, https://creativecommons.org/licenses/by- Copper sulphate sa/3.0/legalcode CuSO4 Auckland Museum Collections from Auckland, Aotearoa New Zealand (https://commons.wikimedia.org/wiki/File:Copper_sulphate_(48723911792).jpg), „Copper sulphate (48723911792)“, https://creativecommons.org/licenses/by/2.0/legalcode Elements & Compounds In nature, most elements are not available in their pure forms, but can be found as compounds. Most elements can interact with other elements to form compounds. -> hydrogen gas burns in oxygen gas: the elements hydrogen and oxygen combine to form the compound water. -> decomposition of water into its elements can be done by passing an electrical current through it. Elements can combine in different ways Water -> linked by chemical bonds (ionic, covalent) H2O ->10 million compounds Chemical reactions: O Bond are broken and remade H H Different substances obtained Covalent bonds  Classifications of Matter Matter separated by physical means? No: Yes: Pure Substance Mixture decomposed by chemical processes? uniform throughout? Yes: No: No: Yes: Element Compound Homogeneous Heterogeneous Mixture Mixture  Mixtures Mixtures contain two or more substances that are not chemically joined. They can be made from both elements and compounds. Because they are not chemically joined, the different substances that form a mixture can be separated easily. The ratio of substances that make up a mixture is not fixed. A fixed formula for a mixture can not be written -> mixed in any proportion Mixtures that appear uniform throughout are called homogeneous mixtures. Mixtures where more than one part is distinguishable are called heterogeneous mixtures. Homogeneous? Gold or water also have a homogeneous look. https://www.qualitylogoproducts.com/stress-balls/gold-nugget-stress-reliever.htm https://www.cityofpriorlake.com/government/departments/public-works/drinking-water-wellhead-protection BUT, they are pure substances. Gold is an element, water is a compound. A pure substance is different from a homogeneous mixture. A pure substance has unique properties that characterize it, like its density. These properties distinguish it from every other substance. A pure substance, by definition, has a fixed composition. Water H2O  Martin Leigh / Getty Images https://www.thoughtco.com/why-oil- and-water-dont-mix-609193 OIL + WATER = Solution The composition of a mixture can vary. A glass of sugar and water can contain either a little sugar or a lot. The substances making up a mixture are called components of the mixture.  Matter separated by physical means? No: Substances Yes: Mixtures Pure Substances Mixtures contain more than one substance Homogeneous Mixture Elements Uniform distribution Made up of only one kind of atom -> uniform in composition and appearance Compounds Heterogeneous Mixture Do not have the same composition, Composed of atoms of two or properties and appearance more elements throughout the mixture. Phase seperations 26  Matter Substances Mixtures Pure Substances Mixtures contain more than one substance Elements Homogeneous Mixture E.g., Na, Cl, H, O E.g., Vinegar, air Compounds Heterogeneous Mixture E.g., Table salt (NaCl), E.g., Wood, soil, ayran water (H2O), sodium hydroxide (NaOH) 27  Elements, Compounds, Mixtures Sodium is an element. Chlorine is an element. When sodium and chlorine bond, they make the compound sodium chloride, commonly known as table salt. https://www.spaceest.com/sodium-chloride.htm NaCl Compounds have different properties than the elements that make them up. Table salt has different properties than sodium, an explosive metal, and chlorine, a poisonous gas.  Elements, Compounds, Mixtures Hydrogen is an element. Oxygen is an element. When hydrogen and oxygen Water atoms bond, they can make the H2O compound water. When salt and water are combined, a mixture is created. Compounds in mixtures retain their individual properties. The sea is a mixture. The Composition of Air 78% Nitrogen 1% Other (Ar, He, Ne, Kr, Xe, CO2...) 21% Oxygen Air is a homogeneous mixture of gases 30  Alloys Solid phase solutions are alloys; homogeneous mixtures of metals or a mixture of a metal and another element. Steel: Iron & Carbon Brass: Copper & Zinc Bronze: Copper & Tin  Physical and Chemical Properties A physical property can be measured and observed without Physical properties include changing the composition or density, color, odor, hardness, identity of a substance. melting and boiling points A physical change does not alter Physical changes include the composition or identity of a changes of state, temperature substance. ice melting A chemical property can only A common chemical be observed when a substance property is flammability, or the ability to burn in oxygen. is changed into another substance. A chemical change alters the Chemical changes include combustion, oxidation, composition or identity of the hydrogen burns in decomposition substance(s) involved. air to form water Theislikerice (https://commons.wikimedia.org/wiki/File:Hydrogen_and_oxygen_react_to_form_water.png), „Hydrogen and oxygen react to form water“, https://creativecommons.org/licenses/by-sa/3.0/legalcode Changes in State of Matter Converting between the three states of matter is a physical change. GAS Melting SOLID LIQUID Freezing 33 Chemical Reactions (Chemical Change) In the course of a chemical reaction, the reacting substances are converted to new substances Physical properties, such as color, often helps to understand that a chemical change has occured.  Extensive and Intensive Properties An extensive property of a material depends upon how much matter is being considered. mass length volume An intensive property of a material does not depend upon how much matter is being considered. density boiling point color Separating the Components of Mixtures Mixtures can be seperated into their components by physical means. These techniques can only be used to separate a mixture of substances, because they are not chemically combined, not bonded. -> Separation done by considering the different porperties of the mixture components such as: size solubility density boiling point Here are some methods of separating mixtures in the laboratory:  Separating Mixtures Filtration Separates: Insoluble solids from liquids. Example: Sand from a sugar solution. https://byjus.com/chemistry/filtration/ Useful for heterogeneous mixtures A funnel with filter paper placed inside to collect solid product Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 40  Separating Mixtures Distillation: If a mixture consists of two or more pure liquids. Boiling points of components are important. Also used to separate a liquid from a solid, and collect the pure liquid. Simple distillation setup: Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 282  Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 39 As the solution is heated, water turns When all the water is boiled off, salt is into steam and is collected via the remaining in the flask. cooled condenser. If the mixture consists of two or more pure liquids: The liquid mixture is heated, initially the more volatile component starts to evaporate. The vapor is cooled in the condenser and turns back to liquid state. Collected as liquid.  Separating Mixtures Chromatograpy: separates dissolved substances with respect to their different interactions with a stationary phase they are travelling through with the aid of a mobile phase. Separating on the basis of differences in the ability of substances to adhere to the solid surface. There are many different types of chromatography. One example is column chromatograpyhy: https://byjus.com/chemistry/differential-extraction-chromatography/ Energy Energy is the capacity to do work or transfer heat. Heat is the energy used to cause the temperature of an object to increase. Work is the energy transferred when a force exerted on an object causes a displacement of that object. Force is any push or pull on an object. Two Fundamental Forms of Energy Kinetic energy is the energy of motion. Its magnitude depends on the object’s mass and velocity. 1 Ek = mv2 2 Potential energy of an object depends on the relative position or condition compared to other objects. Ep = mgh Numbers and Chemistry Numbers play a major role in chemistry. Many topics are quantitative (have a numerical value). Concepts of numbers in science – Units of measurement – Quantities that are measured and calculated – Uncertainty in measurement – Significant figures – Dimensional analysis International System of Units (SI) The measurement units for the seven fundamental properties have been fixed by international agreement. Called the base units. Other units for other properties can be derived by using these base units. SI Base Units Base Quantity Name of Unit Symbol Length meter m Mass kilogram Kg Time second s Electrical current ampere A Temperature kelvin K Amount of substance mole mol Luminous intensity candela cd Metric System Units Base units used in metric system: Mass: gram (g) Length: meter (m) Time: second (s or sec) Temperature: degrees Celsius (°C) or Kelvin (K) Amount of a substance: mole (mol) Volume: cubic centimeter (cc or mL or cm3) or liter (L) Prefixes Used with Units Prefix Symbol Meaning Example peta - P 1,000,000,000,000,000, or 1015 1 petameter (Pm) =1× 1015 m tera - T 1,000,000,000,000, or 1012 1 terameter ( Tm) =1× 1012 m giga - G 1,000,000,000, or 109 1 gigameter ( Gm) =1× 109 m mega - M 1,000,000, or 106 1 megameter (Mm) =1× 106 m kilo - K 1,000, or 103 1 kilometer ( km) =1× 103 m deci - d 1 10, or 10 –1 1 decimeter ( dm) = 0.1m centi - c 1 100, or 10 –2 1 centimeter ( cm) = 0.01m milli - m 1 1,000, or 10 –3 1 millimeter ( mm) = 0.001m micro - μ 1 1000,000, or 10 –6 1 micrometer (μm) = 1× 10 – 6 m nano - n 1 1,000,000,000, or 10 – 9 1 nanometer ( nm) =1× 10 – 9 m pico - p 1 1,000,000,000,000, or 10 –12 1 picometer ( pm) =1× 10 –12 m femto - f 1 1,000,000,000,000,000, or 10 –15 1 femtometer ( fm) =1× 10 –15 m atto - a 1 1,000,000,000,000,000,000, or 10 –18 1 attometer ( am) =1× 10 –18 m Prefixes convert the base units into units that are appropriate for common usage or appropriate measure Matter Matter – anything that occupies space and has mass. mass – measure of the quantity of matter SI standard unit of mass in SI system is the kilogram (kg) (base unit in metric system: gram (g) 1 kg = 1000 g = 1× 103 g The terms “mass” and “weight” refer to different quantities. In scientific terms, weight is the force that gravity exerts on an object.  Volume Volume (V) – is not a base unit for SI Volume it is a derived unit from length Length is a Cubic meter = m × m × m = m3 measure of distance. The meter (m) is the base unit. ( ) 3 3 –2 Glassware for 1 cm = 1× 10 m = 1× 10 – 6 m3 measuring volume = (1× 10 m) 3 –1 3 1 dm = 1× 10 – 3 m3 Other commonly used units for volume are the liter (L) and the milliliter (mL).  A liter is a cube 1 decimeter (dm) long 1L = 1000 mL = 1000 cm3 =1 dm3 on each side.  A milliliter is a cube 1 centimeter (cm) long on each side, also called 1 cubic centimeter (cc) 1 mL = 1 cm3 (cm × cm × cm = cm3). Glassware for Measuring Volume Common glassware used in laboratories to deliver pure liquids or solutions Density Density is physical property. The density of a substance is the ratio of the mass of a sample of the substance to its volume. Density is an intensive property, density of a material does not depend upon how much matter is being considered. Densities of Some Substances at 25 °C Substance Density (g/cm3) SI derived unit for density is Air 0.001 3 3 Ethanol 0.79 1 g cm =1g mL = 1000 kg m Water 1.00 Graphite 2.2 Table salt 2.2 mass density = Aluminum 2.70 volume Diamond 3.5 Iron 7.9 Lead 11.3 m d= Mercury 13.6 V Gold 19.3 how much mass is packed in a given volume Osmium† 22.6 Temperature Temperature: considered as the “hotness & coldness” of an object that determines the direction of heat flow. Heat flows spontaneously from an object with a higher temperature to an object with a lower temperature. °F = 9/5(°C) + 32 °C = 5/9(°F − 32) K = °C + 273.15 In Kelvin scale, the lowest possible temperature is called absolute zero (0 K) based on the properties of gases no negative Kelvin temperatures 52 Energy The unit of energy: Joule(J) It is a derived unit: KE=½mv2 If the object is 2kg, and it moves at 1m/s, it will posses 1J of kinetic energy: 1 J = ½ (2 kg) (1 m/s)2 or: 1 J = 1 kg · m2/s2 The kJ is commonly used for chemical change -> 1 kJ = 1000 J Historically, the calorie was used: 1 cal = 4.184 J This calorie is NOT the nutritional Calorie. Nutritional Calorie is a kcal. 1 nutritional Calorie = 1 kcal = 1000 cal = 4.184 kJ Numbers Encountered in Science Exact numbers are counted or given by definition. Ex: there are 12 eggs in 1 dozen Inexact (or measured) numbers depend on how they were determined. -> Scientific instruments have limitations (equipment errors) and individuals can read some instrumentation differently (human errors). Uncertainty in Measurements Different measuring devices have different uses and different degrees of accuracy. All measured numbers have some degree of inaccuracy. The last digit measured is considered reliable, but NOT exact. Praphai Donphaimueang (https://commons.wikimedia.org/wiki/File:Grauduate_cylinder_reading.png), https://creativecommons.org/licenses/by-sa/4.0/legalcode Uncertainty in Measurements Accuracy refers to how closely individual Precision is a measure of how closely measurements agree with the correct, or individual measurements agree with “true,” value. one another. -> Experimentally, we often take several measurements and determine a standard deviation. Helmenstine, T. (2021, August 16). What is the difference between accuracy and precision? Science Notes and Projects. https://sciencenotes.org/what-is-the-difference-between-accuracy-and-precision/  Significant Figures All digits of a measured quantity, including the uncertain ones, are called significant figures. When rounding calculated numbers, we pay attention to significant figures so we do not overstate the accuracy of our answers. 1. All nonzero digits are significant. 2. Zeroes between nonzero digits are significant. 3. Zeroes at the beginning of a number are never significant. (leading zeros) 4. Zeroes at the end of a number are significant if it contains a decimal point. (trailing zeros) 5. The exponential term does not add to the number of significant figures. 300042 0.000034 0.0002500 190000 1000. 6 sf 2 sf 4 sf 2 sf 4 sf Significant Figures in Calculations In Calculations: 1. The least certain measurement limits the number of significant figures in the answer. When the result contains more than the correct number of significant figures, it must be rounded off. 2. When addition or subtraction is performed, answers are rounded to the least significant decimal place. 101.25 + 3536.2 + 123.448 = 3760.898 3760.9 Digits to be dropped Least precise number, only 1 digit after decimal Last digit retained 26.4214 − 9.4557 = 16.9657 No digit to be dropped, all retained 1.327 + 8.6 + 31.7798 = 41.7068 41.7 Digits to be dropped Least precise number, «0» can not round «7» to «8» only 1 digit after decimal Last digit retained  Significant Figures in Calculations 3. When multiplication or division is performed, answers are rounded to the same number of digits as the measurement with the fewest number of significant figures. 𝑔𝑔 0.3 𝑚𝑚𝑚𝑚 𝑥𝑥 0.7 = 0.21 0.2 𝑔𝑔 When the result contains more than the correct 𝑚𝑚𝑚𝑚 number of significant figures, it must be rounded 1 sf 1 sf 2 sf 1 sf off. answer rounded to the same number of digits 5.20 𝑥𝑥 6.129 = 31.8770 31.9 as the measurement with the fewest number 3 sf 4 sf 6 sf of significant figures. 3 sf unit must be included as well. Sample Exercise 1.8 𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉 = 𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤 𝑥𝑥 𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙 𝑥𝑥 ℎ𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒 𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉 = 15.5 𝑐𝑐𝑐𝑐 𝑥𝑥 27.3 𝑐𝑐𝑐𝑐 𝑥𝑥 5.4 𝑐𝑐𝑐𝑐 3 sf 3 sf 2 sf Least number of significant figures 𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉 = 2285.01 𝑐𝑐𝑐𝑐3 2.3 𝑥𝑥 103 𝑐𝑐𝑐𝑐3 6 sf answer rounded to 2 sf, reported in exponential notation Scientific Notation Dimensional Analysis Dimensional analysis is used to change units. We apply conversion factors (e.g., 1 in. = 2.54 cm), which are equalities. We can set up a ratio of comparison for the equality: 1 in./2.54 cm or 2.54 cm/1 in. We use the ratio which allows us to change units (puts the units we have in the denominator to cancel). We can use multiple conversions, as long as each one is an equality. References Chemistry, The Central Science, 15th edition, By Theodore L. Brown, H. Eugene LeMay, Jr., Bruce E. Bursten, Catherine, J. Murphy, Patrick M. Woodward, Matthew W. Stoltzfus, Pearson Press, USA (9781292407586-Mastering Chemistry Brown Chemistry GE 15e) Chemistry, 13th Edition by Raymond Chang, Jason Overby, McGraw-Hill (2019)