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General and Inorganic Chemistry

General and Inorganic Chemistry
General and Inorganic Chemistry I Lecture 1 Istv an Szalai E otv os University Istv an Szalai (E otv os University) Lecture 1 1 / 45Outline 1 Introduction 2 Matter and energy 3 Foundations of Chemistry Istv an Szalai (E otv os University) Lecture 1 2 / 45Introduction Informations Lecture (3+2 hours/week) + laboratory practice (5 hours/week) Lecturers: Istv an Szalai (Monday 3 hours) nd contacts: ELTE Chemistry building 2 oor room: 241 email: szalai.istvanchem.elte.hu web: nlcd.elte.hu/szalai/teaching.html Szabolcs B eni (Tuesday 2 hours) rd  contacts: 1085 Budapest Ull oi ut  26 3 oor web: scholar.semmelweis.hu/beniszabolcs/oktatasitevekenyseg Laboratory supervisors: Anik o Vasanits, Katalin Per enyi and Viktor Mihucz Istv an Szalai (E otv os University) Lecture 1 3 / 45Introduction Informations Laboratory grade: average result of the three Major Tests and the short tests Theoretical grade: oral exam during the examination period (DecemberJanuary). The registration for the exam can be made in the Neptun system. The theoretical exam covers the topics discussed during the lectures and the laboratory practices (calculations). Those who failed in laboratory not allowed to take the theoretical exam, they must repeat the whole semester Istv an Szalai (E otv os University) Lecture 1 4 / 45Introduction Lecture notes and books Slides: nlcd.elte.hu/szalai/teaching.html en.wikibooks.org/wiki/GeneralChemistry Istv an Szalai (E otv os University) Lecture 1 5 / 45Matter and energy Chemistry Chemistry is the science that describes matter, its properties, the changes it undergoes, and the energy changes that accompany those processes. Inorganic chemistry Organic chemistry Physical chemistry Biochemistry Applied Chemistry: Analytical chemistry, Pharmaceutical Chemistry, . . . Istv an Szalai (E otv os University) Lecture 1 6 / 45Matter and energy Outline of the semester Introduction Structure of Atoms and Molecules Chemical Reactions and Equilibrium Thermochemistry Chemical Kinetics Istv an Szalai (E otv os University) Lecture 1 7 / 45Matter and energy Lecture 1: Introduction and properties of matter Reading: en.wikibooks.org/wiki/GeneralChemistry/Propertiesof Matter Istv an Szalai (E otv os University) Lecture 1 8 / 45Matter and energy Matter and Energy Matter: anything that has both mass and volume. Mass: a measure of an object's resistance to change in motion (inertia). F = ma Volume: a measure of the amount of space occupied by an object. States of matter: Gases: They occupy all parts of any vessel in which they are con ned. They are capable of in nite expansion and are compressed easily. The individual particles are quite far apart. Liquids: The individual particles are con ned to a given volume. A liquid assumes the shape of the container. They are very hard to compress. Istv an Szalai (E otv os University) Lecture 1 9 / 45Matter and energy Matter and Energy States of matter: Solids: They are rigid and have de nite shapes. Volumes of solids do not vary much with changes in temperature. In crystalline solids the individual particles occupy de nite positions in the crystal structure. Plasma: Like a gas, plasma does not have de nite shape or volume. Unlike gases, plasmas are electrically conductive, produce magnetic elds and electric currents, and respond strongly to electromagnetic forces. Positively charged nuclei swim in a "sea" of freelymoving disassociated electrons Istv an Szalai (E otv os University) Lecture 1 10 / 45Matter and energy Matter and Energy States of matter: Istv an Szalai (E otv os University) Lecture 1 11 / 45Matter and energy Matter and Energy Energy: is a conserved extensive property of a physical system, which cannot be observed directly but can be calculated from its state. 1 2 Forms of energy: kinetic energy (E = mv ), potential energy kin 2 (E = mgh), heat, electrical energy. . . pot Law of conservation of matter and energy: There is no change in the quantity of matter and energy during any chemical or physical change. Massenergy equivalence is a concept formulated by Albert Einstein that explains the relationship between mass and energy. 2 E = mc Istv an Szalai (E otv os University) Lecture 1 12 / 45Matter and energy Law of conservation of matter and energy Chemical reaction: 2 H + O 2 H O 2 2 2 Conservation of Matter: 2 mol H + 1 mol O 2 mol H O 2 2 2 Conservation of Mass (mass is not generally conserved): 4 g H + 32 g O 36 g H O 2 2 2 2 H + O 2 H O + 572000 J (energy) 2 2 2 2 8 2 12 m = E=c = 572000 J=(3 10 m/s) = 6; 35 10 g The mass associated with chemical amounts of energy is too small to measure. Istv an Szalai (E otv os University) Lecture 1 13 / 45Matter and energy Physical Properties A physical change occurs with no change in chemical composition. e.g.: boiling, melting, vaporization. . . Physical properties altered signi cantly as matter undergoes physical changes. Extensive properties: quantity proportional to the quantity of material in the system. mass, volume, total energy Intensive properties: independent of the quantity of material density, pressure, temperature Istv an Szalai (E otv os University) Lecture 1 14 / 45Matter and energy International System of units (SI Units) length meter m mass kilogram kg time second s electric current ampere A temperature Kelvin K luminous intensity candela cd amount of substance mole mol meter: the lenght equal to the distance traveled by light in vacuum in 1/299,792,458 seconds. mol: the amount of substance that contains as many entities (atoms or 12 other particles) as there are atoms in 0.012 kg of pure C. 1 mole = 6 23 6:022 10 Istv an Szalai (E otv os University) Lecture 1 15 / 45Matter and energy Derived Units 2 area square meter m 3 volume cubic meter m 3 density kilogram/cubic meter kg/m 2 force newton N kgm/s 2 pressure pascal Pa N/m 2 2 energy joule J kgm /s electric charge coulomb C As electric potential di erence volt V J/(As) Istv an Szalai (E otv os University) Lecture 1 16 / 45Matter and energy Derived Units Density: m d = V 3 Suppose an object has a mass of 15.0 g and a volume of 10.0 cm . What is the density m 15:0 g 3 d = = = 1:50 g/cm 3 V 10:0 cm Istv an Szalai (E otv os University) Lecture 1 17 / 45Matter and energy SI pre xes 12 1 10 tera T 10 deci d 9 2 10 giga G 10 centi c 6 3 10 mega M 10 milli m 3 6 10 kilo k 10 micro  2 9 10 hecto h 10 nano n 1 12 10 deka da 10 pico p 15 10 femto f 18 10 atto a Istv an Szalai (E otv os University) Lecture 1 18 / 45Matter and energy SI pre xes 1 kg=1000 g ( the mass of 1 L water) 6 1g=10 g=0.000001 g (a typical small sand grain mass is about 3g) 9 1 ng=10 g=0.000000001 g (mass of an average human cell) 9 1 nm=10 m=0.000000001 m (a strand of human DNA is 2.5 nm in diameter) Istv an Szalai (E otv os University) Lecture 1 19 / 45Matter and energy Measurement and signi cant gures If you repeat a particular measurement, you usually do not obtain precisely the same result, because each measurement is subject to experimental error. Precision refers to the closeness of the set of values obtained from identical measurements of a quantity. Accuracy refers to the closeness of a single measurement to its true value. Signi cant gures are those digits in a measured number (or in the result of a calculation with measured numbers) that include all certain digits plus a nal digit having some uncertainty. Istv an Szalai (E otv os University) Lecture 1 20 / 45Matter and energy Measurement and signi cant gures All digits are signi cant except zeros at the beginning of the number. Thus, 9.12 cm, 0.912 cm, and 0.00912 cm all contain three signi cant gures. Terminal zeros ending at the right of the decimal point are signi cant. Each of the following has three signi cant gures: 9.00 cm, 9.10 cm, 90.0 cm. Istv an Szalai (E otv os University) Lecture 1 21 / 45Matter and energy Measurement and signi cant gures Multiplication and division. When multiplying or dividing measured quantities, give as many signi cant gures in the answer as there are in the measurement with the least number of signi cant gures. Suppose you want to calculate the solubility of a substance (the amount that dissolves in 100 g of water). You nd that 0.0634 gram of the substance dissolves in 25.31 grams of water. The amount dissolving in 100.0 grams is 0:0634g 100:0 g of water 5:31 g of water Performing it on a pocket calculator you get 0.250493875. The measurement 0.0634 gram has the least number of signi cant gures (three). Therefore, you report the answer to three signi cant gures, that is, 0.250 g. Istv an Szalai (E otv os University) Lecture 1 22 / 45Matter and energy Measurement and signi cant gures Addition and subtraction. When adding or subtracting measured quantities, give the same number of decimal places in the answer as there are in the measurement with the least number of decimal places. Now consider the addition of 184.2 grams and 2.324 grams. On a calculator, you nd that the result is 186.524. But because the quantity 184.2 grams has the least number of decimal places one, whereas 2.324 grams has three, the answer is 186.5 grams. Istv an Szalai (E otv os University) Lecture 1 23 / 45Matter and energy Measurement and signi cant gures Rounding is the procedure of dropping nonsigni cant digits in a calculation result and adjusting the last digit reported. The general procedure is as follows: Look at the leftmost digit to be dropped. If this digit is 5 or greater, add 1 to the last digit to be retained and drop all digits farther to the right. Thus, rounding 1.2151 to three signi cant gures gives 1.22. If this digit is less than 5, simply drop it and all digits farther to the right. Rounding 1.2143 to three signi cant gures gives 1.21. Istv an Szalai (E otv os University) Lecture 1 24 / 45Matter and energy Chemical properties They are exhibited by matter as it undergoes changes in composition: acidity redox properties reactivity. . . Chemical changes are transformations in which substances are converted into other substances. e.g..: burning, decomposition . . . 3 Br (l) + 2 Al(s) 2 AlBr (s) 2 3 Question: A sample of 27.0 g of aluminum yields 266.7 g of aluminum bromide. How many grams of bromine react with 15.0 g of aluminum Answer: 133 g Istv an Szalai (E otv os University) Lecture 1 25 / 45Matter and energy Classi cation of matter Pure Substances: Fixed composition. Cannot be separated into simpler substances by physical methods. Elements: cannot be decomposed into simpler substances by chemical changes Compounds: can be decomposed into simpler substances by chemical changes, always in a de nite ratio Istv an Szalai (E otv os University) Lecture 1 26 / 45Matter and energy Classi cation of matter Mixtures: Variable composition. Components retain their characteristic properties. May be separated into pure substances by physical methods (e.g. distillation). Mixtures of di erent compositions may have widely di erent properties. Homogeneous mixtures: components are indistinguishable; have same composition throughout (e.g. solutions, alloys). Heterogeneous mixtures: components are distinguishable; do not have same composition throughout (e.g. muddy river water). Istv an Szalai (E otv os University) Lecture 1 27 / 45Matter and energy Compounds Law of de nite proportions: pure compounds always consist of the same elements combined in the same proportion by mass. water 11.1 hydrogen 88.9 oxygen carbon dioxide 27.3 carbon 72.7 oxygen Istv an Szalai (E otv os University) Lecture 1 28 / 45Matter and energy Compounds Law of Multiple Proportions: If two elements form more than one compound, in these compounds masses of one element that combine with a xed mass of the other element are in a ratio of integer numbers. N:O N O 1:0.57 2 NO 1:1.14 0.57:1.14=1:2 NO 1:2.28 0.57:2.28=1:4 2 Istv an Szalai (E otv os University) Lecture 1 29 / 45Foundations of Chemistry Foundations of Chemistry Atoms: the smallest particle of an element that maintains its chemical identity. Structure of atoms: 10 The diameter of an atom is 10 m (0.1 nm). The nucleus contains protons and neutrons. The diameter of a 15 nucleus is 10 m. Particle Mass Charge 27 19 proton 1:672 10 kg +1:602 10 C 27 neutron 1:675 10 kg none 31 19 electron 9:109 10 kg 1:602 10 C + m(p )  1840 m(e ) Istv an Szalai (E otv os University) Lecture 1 30 / 45Foundations of Chemistry Foundations of Chemistry Atomic number (Z ) = number of protons in the nucleus Mass number (A) = number of protons + number of neutrons A 12 Symbol: X, C Z 6 1 Isotopes: atoms for the same elements with di erent masses e.g H, 1 2 3 H, H 1 1 12 Atomic mass unit: exactly 1/12 of the mass of an atom of C (1 6 27 amu = 1:6606 10 kg) On this scale the atomic weight of hydrogen is 1.00794 amu. Relative atomic mass: atomic weight divided by the atomic mass unit Relative atomic weight of hydrogen is 1.00794. Istv an Szalai (E otv os University) Lecture 1 31 / 45Foundations of Chemistry Foundations of Chemistry In the molecules two or more atoms are bonded together. An ion is an atom or group of atoms that carries an electric charge. Ions that possess a positive charge are called cations. Those carrying negative charge are called anions. A radical is a group of atoms which have odd number of electrons. Istv an Szalai (E otv os University) Lecture 1 32 / 45Foundations of Chemistry Problems What is the volume of a C atom if its radius is 77 pm 4 3 V = R  3 4 12 3 V = (77 10 m)  3 30 3 V = 1:91 10 m Istv an Szalai (E otv os University) Lecture 1 33 / 45Foundations of Chemistry Problems When a mixture of aluminum powder and iron(III) oxide is ignited, it produces molten iron and aluminum oxide. In an ex periment, 5.40 g of aluminum was mixed with 18.50 g of iron(III) oxide. At the end of the reaction, the mixture contained 11.17 g of iron, 10.20 g of aluminum oxide, and an undeter mined amount of unreacted iron(III) oxide. No aluminum was left. What is the mass of the iron(III) oxide Answer: 2.53 g Istv an Szalai (E otv os University) Lecture 1 34 / 45Foundations of Chemistry Problems A beaker weighed 53.10 g. To the beaker was added 5.348 g of iron pellets and 56.1 g of hydrochloric acid. What was the to tal mass of the beaker and the mixture (before reaction) Express the answer to the correct number of signi cant gures. Answer: 114.5 g Istv an Szalai (E otv os University) Lecture 1 35 / 45Foundations of Chemistry Problems 23 What is the number of protons, neutrons and electrons in a Na atom, in 1g of Na and in 1 mol of Na 23 + + + Na atom: N(p )=11, N(e )=11, N(n )=12 1g 23 22 1g Na: N(atoms)= 6 10 = 2:61 10 23g=mol + 22 23 N(p )=11 2:61 10 =2:87 10 + 22 23 N(e )=11 2:61 10 =2:87 10 + 22 23 N(n )=12 2:61 10 =3:13 10 23 1 mol Na: N(atoms)=6 10 + 23 24 N(p )=11 6 10 =6:6 10 + 23 24 N(e )=11 6 10 =6:6 10 + 23 24 N(n )=12 6 10 =7:2 10 Istv an Szalai (E otv os University) Lecture 1 36 / 45Foundations of Chemistry Problems + + What is the charge of a Na ion and 1g of H + + 19 Na ion: Q(Na ) = +1:602 10 C + 1g 1 23 23 1g H : N = 6 10 mol = 6 10 1g=mol 19 23 4 Q = +1:602 10 C 6 10 = 9:612 10 C Istv an Szalai (E otv os University) Lecture 1 37 / 45Foundations of Chemistry Problems What is the atomic weight of magnesium according to the above data Isotope Abudance Mass (amu) 24 Mg 78.99 23.985 25 Mg 10.00 24.986 26 Mg 11.01 25.983 Atomic weight of magnesium= 0:7899 23:985 + 0:1000 24:986 + 0:1101 25:983 = 24:30amu Istv an Szalai (E otv os University) Lecture 1 38 / 45Foundations of Chemistry Problems Cocaine has the following percent composition by mass: 67.30 C, 6.93 H, 21.15 O and 4.62 N. What is the simplest formula of cocaine 67:30 C = 5:608 12 6:93 H = 6:93 1 21:15 O = 1:322 16 4:62 N = 0:33 14 5:608 C = 17 0:33 6:93 H = 21 0:33 1:322 O = 4 0:33 0:33 N = 1 0:33 C H O N 12 21 4 Istv an Szalai (E otv os University) Lecture 1 39 / 45Foundations of Chemistry Quiz Which one of the following is an example of a chemical change A. Mixing sand and sugar B. Cutting a piece of paper into two pieces C. Ice melting to water D. Burning a piece of paper to form carbon dioxide and water E. Mixing water and orange juice Istv an Szalai (E otv os University) Lecture 1 40 / 45Foundations of Chemistry Quiz Which of the following is an example of a solution A. Water B. A combination of red and white chalk dust C. Carbon disul de (a chemical combination of carbon and sulfur) D. Aluminum E. Sugar water Istv an Szalai (E otv os University) Lecture 1 41 / 45Foundations of Chemistry Quiz Which of the following are substances A. Elements and solutions B. Elements and compounds C. Heterogeneous mixtures only D. Heterogeneous mixtures and solutions E. Elements only Istv an Szalai (E otv os University) Lecture 1 42 / 45Foundations of Chemistry Quiz Which one of the following is an extensive property A. Temperature B. Mass C. Taste D. Density E. Color Istv an Szalai (E otv os University) Lecture 1 43 / 45Foundations of Chemistry Quiz Which one of the following is a chemical change A. Iron lings are separated from sand using a magnet B. Liquid nitrogen boils to become nitrogen gas C. Gunpowder is exploded D. Antifreeze is added to water in an automobile radiator E. A shaken cola can is opened producing a spray of soda and carbon dioxide gas Istv an Szalai (E otv os University) Lecture 1 44 / 45Foundations of Chemistry Quiz Which of the following converts chemical energy to mechanical energy A. A waterwheel B. A kerosene heater C. A gasolinepowered automobile engine D. A battery attached to a light bulb E. A solar oven Istv an Szalai (E otv os University) Lecture 1 45 / 45
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