G I C I L I S E U
General and Inorganic Chemistry ILecture 1
István Szalai
Eötvös University
2019
Outline
1 Introduction
2 Matter and energy
3 Foundations of Chemistry
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Introduction
Informations
Lecture (3+2 hours/week) + laboratory practice (5hours/week)Lecturers:István Szalai (Monday 3 hours)contacts: ELTE Chemistry building 5th �oor room: 5.117email: [email protected]: nlcd.elte.hu/szalai/teaching.htmlNorbert Szoboszlai and Szabolcs Béni (Tuesday 2 hours)
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Informations
Laboratory grade: average result of the Major Tests and theshort testsTheoretical grade: oral exam during the examination period(December-January). The registration for the exam can bemade in the Neptun system. The theoretical exam covers thetopics discussed during the lectures and the laboratorypractices (including calculations).
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Lecture notes and books
Slides: nlcd.elte.hu/szalai/teaching.htmlen.wikibooks.org/wiki/General_ChemistryOpen Textbook Libraryhttps://open.umn.edu/opentextbooks/BookDetail.aspx?bookId=69
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Chemistry
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Chemistry
Chemistry is the science that describes matter, its properties,the changes it undergoes, and the energy changes thataccompany those processes.
Inorganic chemistryOrganic chemistryPhysical chemistryBiochemistryApplied Chemistry:Analytical chemistry, Pharmaceutical Chemistry, . . .
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Outline of the semester
IntroductionStructure of Atoms and MoleculesChemical Reactions and EquilibriumThermochemistryChemical Kinetics
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Matter and energy
Lecture 1: Introduction and properties ofmatter
Reading:en.wikibooks.org/wiki/General_Chemistry/Properties_of_Matter
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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 = maVolume: a measure of the amount of space occupied by anobject.
States of matter:Gases: They occupy all parts of any vessel in which they arecon�ned. They are capable of in�nite expansion and arecompressed easily. The individual particles are quite farapart.Liquids: The individual particles are con�ned to a givenvolume. A liquid assumes the shape of the container. Theyare very hard to compress.
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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 = maVolume: a measure of the amount of space occupied by anobject.
States of matter:Gases: They occupy all parts of any vessel in which they arecon�ned. They are capable of in�nite expansion and arecompressed easily. The individual particles are quite farapart.Liquids: The individual particles are con�ned to a givenvolume. A liquid assumes the shape of the container. Theyare very hard to compress.
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Matter and Energy
States of matter:Solids: They are rigid and have de�nite shapes. Volumes ofsolids do not vary much with changes in temperature. Incrystalline solids the individual particles occupy de�nitepositions in the crystal structure.Plasma: Like a gas, plasma does not have de�nite shape orvolume. Unlike gases, plasmas are electrically conductive,produce magnetic �elds and electric currents, and respondstrongly to electromagnetic forces. Positively charged nucleiswim in a "sea" of freely-moving disassociated electrons
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Matter and Energy
States of matter:
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Matter and Energy
Energy: is a conserved extensive property of a physical system,which cannot be observed directly but can be calculated from itsstate.
Forms of energy: kinetic energy (Ekin = 12mv
2), potentialenergy (e.g. Epot = mgh), heat, electrical energy. . .Law of conservation of matter and energy: There is nochange in the quantity of matter and energy during anychemical or physical change.Mass-energy equivalence is a concept formulated by AlbertEinstein that explains the relationship between mass andenergy.
E = mc2
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Law of conservation of matter and energy
Chemical reaction:2H2 + O2 −−→ 2H2O
Conservation of Matter:2 molH2 + 1 molO2 −−→ 2 molH2OConservation of Mass (mass is not generally conserved):4 gH2 + 32 gO2 −−→ 36 gH2O2H2 + O2 −−→ 2H2O+ 572000 J (energy)m = E/c2 = 572000 J/(3× 108m/s)2 = 6, 35× 10−12 gThe mass associated with chemical amounts of energy is toosmall to measure.
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Law of conservation of matter and energy
Chemical reaction:2H2 + O2 −−→ 2H2OConservation of Matter:2 molH2 + 1 molO2 −−→ 2 molH2O
Conservation of Mass (mass is not generally conserved):4 gH2 + 32 gO2 −−→ 36 gH2O2H2 + O2 −−→ 2H2O+ 572000 J (energy)m = E/c2 = 572000 J/(3× 108m/s)2 = 6, 35× 10−12 gThe mass associated with chemical amounts of energy is toosmall to measure.
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Law of conservation of matter and energy
Chemical reaction:2H2 + O2 −−→ 2H2OConservation of Matter:2 molH2 + 1 molO2 −−→ 2 molH2OConservation of Mass (mass is not generally conserved):4 gH2 + 32 gO2 −−→ 36 gH2O
2H2 + O2 −−→ 2H2O+ 572000 J (energy)m = E/c2 = 572000 J/(3× 108m/s)2 = 6, 35× 10−12 gThe mass associated with chemical amounts of energy is toosmall to measure.
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Law of conservation of matter and energy
Chemical reaction:2H2 + O2 −−→ 2H2OConservation of Matter:2 molH2 + 1 molO2 −−→ 2 molH2OConservation of Mass (mass is not generally conserved):4 gH2 + 32 gO2 −−→ 36 gH2O2H2 + O2 −−→ 2H2O+ 572000 J (energy)
m = E/c2 = 572000 J/(3× 108m/s)2 = 6, 35× 10−12 gThe mass associated with chemical amounts of energy is toosmall to measure.
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Law of conservation of matter and energy
Chemical reaction:2H2 + O2 −−→ 2H2OConservation of Matter:2 molH2 + 1 molO2 −−→ 2 molH2OConservation of Mass (mass is not generally conserved):4 gH2 + 32 gO2 −−→ 36 gH2O2H2 + O2 −−→ 2H2O+ 572000 J (energy)m = E/c2 = 572000 J/(3× 108m/s)2 = 6, 35× 10−12 gThe mass associated with chemical amounts of energy is toosmall to measure.
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Physical Properties
A physical change occurs with no change in chemicalcomposition. e.g.: boiling, melting, vaporization. . .Physical properties altered signi�cantly as matter undergoesphysical changes.
Extensive properties: quantity proportional to the quantityof material in the system. mass, volume, total energyIntensive properties: independent of the quantity ofmaterial density, pressure, temperature
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International System of units (SI Units)
length meter mmass kilogram kgtime second selectric current ampere Atemperature Kelvin Kluminous intensity candela cdamount of substance mole molmeter: the lenght equal to the distance traveled by light invacuum in 1/299,792,458 seconds.mol: the amount of substance that contains as many entities(atoms or other particles) as there are atoms in 0.012 kg of pure126C. 1 mole = 6.022× 1023
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Derived Units
area square meter m2
volume cubic meter m3
density kilogram/cubic meter kg/m3
force newton N kg×m/s2pressure pascal Pa N/m2
energy joule J kg×m2/s2electriccharge coulomb C A×selectricpotential di�erence volt V J/(A×s)
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Derived Units
Density:d =
mV
Suppose an object has a mass of 15.0 g and a volume of 10.0 cm3.What is the density?
d =mV =
15.0g10.0 cm3 = 1.50 g/cm3
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Derived Units
Density:d =
mV
Suppose an object has a mass of 15.0 g and a volume of 10.0 cm3.What is the density?
d =mV =
15.0g10.0 cm3 = 1.50 g/cm3
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SI prefixes
1012 tera T 10−1 deci d109 giga G 10−2 centi c106 mega M 10−3 milli m103 kilo k 10−6 micro µ102 hecto h 10−9 nano n101 deka da 10−12 pico p
10−15 femto f10−18 atto a
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SI prefixes
1 kg=1000g (≈ the mass of 1 L water)
1µg=10−6 g=0.000001 g (a typical small sand grain mass is about3µg)1 ng=10−9 g=0.000000001 g (mass of an average human cell)1 nm=10−9m=0.000000001m (a strand of human DNA is 2.5 nmin diameter)
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SI prefixes
1 kg=1000g (≈ the mass of 1 L water)1µg=10−6 g=0.000001 g (a typical small sand grain mass is about3µg)
1 ng=10−9 g=0.000000001 g (mass of an average human cell)1 nm=10−9m=0.000000001m (a strand of human DNA is 2.5 nmin diameter)
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SI prefixes
1 kg=1000g (≈ the mass of 1 L water)1µg=10−6 g=0.000001 g (a typical small sand grain mass is about3µg)1 ng=10−9 g=0.000000001 g (mass of an average human cell)
1 nm=10−9m=0.000000001m (a strand of human DNA is 2.5 nmin diameter)
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SI prefixes
1 kg=1000g (≈ the mass of 1 L water)1µg=10−6 g=0.000001 g (a typical small sand grain mass is about3µg)1 ng=10−9 g=0.000000001 g (mass of an average human cell)1 nm=10−9m=0.000000001m (a strand of human DNA is 2.5 nmin diameter)
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SI prefixes
1 kg=1000g (≈ the mass of 1 L water)1µg=10−6 g=0.000001 g (a typical small sand grain mass is about3µg)1 ng=10−9 g=0.000000001 g (mass of an average human cell)1 nm=10−9m=0.000000001m (a strand of human DNA is 2.5 nmin diameter)
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Measurement and significant figures
If you repeat a particular measurement, you usually do notobtain precisely the same result, because eachmeasurement is subject to experimental error.Precision refers to the closeness of the set of valuesobtained from identical measurements of a quantity.Accuracy refers to the closeness of a single measurement toits true value.Signi�cant �gures are those digits in a measured number (orin the result of a calculation with measured numbers) thatinclude all certain digits plus a �nal digit having someuncertainty.
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Measurement and significant figures
All digits are signi�cant except zeros at the beginning of thenumber. Thus, 9.12 cm, 0.912 cm, and 0.00912 cm all containthree signi�cant �gures.Terminal zeros ending at the right of the decimal point aresigni�cant. Each of the following has three signi�cant�gures: 9.00 cm, 9.10 cm, 90.0 cm.
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Measurement and significant figures
Multiplication and division. When multiplying or dividingmeasured quantities, give as many signi�cant �gures in theanswer as there are in the measurement with the leastnumber of signi�cant �gures.
Suppose you want to calculate the solubility of a substance (theamount that dissolves in 100 g of water). You �nd that 0.0634gram of the substance dissolves in 25.31 grams of water. Theamount dissolving in 100.0 grams is
100.0g of water× 0.0634g5.31 g of water
Performing it on a pocket calculator you get 0.250493875.
Themeasurement 0.0634 gram has the least number of signi�cant�gures (three). Therefore, you report the answer to threesigni�cant �gures, that is, 0.250 g.
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Measurement and significant figures
Multiplication and division. When multiplying or dividingmeasured quantities, give as many signi�cant �gures in theanswer as there are in the measurement with the leastnumber of signi�cant �gures.
Suppose you want to calculate the solubility of a substance (theamount that dissolves in 100 g of water). You �nd that 0.0634gram of the substance dissolves in 25.31 grams of water. Theamount dissolving in 100.0 grams is
100.0g of water× 0.0634g5.31 g of water
Performing it on a pocket calculator you get 0.250493875. Themeasurement 0.0634 gram has the least number of signi�cant�gures (three). Therefore, you report the answer to threesigni�cant �gures, that is, 0.250 g.
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Measurement and significant figures
Addition and subtraction. When adding or subtractingmeasured quantities, give the same number of decimalplaces in the answer as there are in the measurement withthe least number of decimal places.
Now consider the addition of 184.2 grams and 2.324 grams. On acalculator, you �nd that the result is 186.524.
But because thequantity 184.2 grams has the least number of decimal places one,whereas 2.324 grams has three, the answer is 186.5 grams.
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Measurement and significant figures
Addition and subtraction. When adding or subtractingmeasured quantities, give the same number of decimalplaces in the answer as there are in the measurement withthe least number of decimal places.
Now consider the addition of 184.2 grams and 2.324 grams. On acalculator, you �nd that the result is 186.524. But because thequantity 184.2 grams has the least number of decimal places one,whereas 2.324 grams has three, the answer is 186.5 grams.
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Measurement and significant figures
Rounding is the procedure of dropping nonsigni�cant digits in acalculation result and adjusting the last digit reported. Thegeneral procedure is as follows: Look at the leftmost digit to bedropped.
If this digit is 5 or greater, add 1 to the last digit to beretained 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 fartherto the right. Rounding 1.2143 to three signi�cant �gures gives1.21.
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Chemical properties
They are exhibited by matter as it undergoes changes incomposition:
acidityredox properties. . .
Chemical changes are transformations in which substances areconverted into other substances.3 Br2(l)+ 2 Al(s) −−→ 2 AlBr3(s)
3 Br2(l) + 2 Al(s)→ 2 AlBr3(s)25 45
Classification of matter
Pure Substances:Fixed composition. Cannot be separated into simpler substancesby physical methods.
Elements: cannot be decomposed into simpler substancesby chemical changesCompounds: can be decomposed into simpler substances bychemical changes, always in a de�nite ratio
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Classification of matter
Pure Substances:Fixed composition. Cannot be separated into simpler substancesby physical methods.
Elements: cannot be decomposed into simpler substancesby chemical changes
Compounds: can be decomposed into simpler substances bychemical changes, always in a de�nite ratio
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Classification of matter
Pure Substances:Fixed composition. Cannot be separated into simpler substancesby physical methods.
Elements: cannot be decomposed into simpler substancesby chemical changesCompounds: can be decomposed into simpler substances bychemical changes, always in a de�nite ratio
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Classification of matter
Mixtures:Variable composition. Components retain their characteristicproperties. May be separated into pure substances by physicalmethods (e.g. distillation). Mixtures of di�erent compositionsmay 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 riverwater).
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Classification of matter
Mixtures:Variable composition. Components retain their characteristicproperties. May be separated into pure substances by physicalmethods (e.g. distillation). Mixtures of di�erent compositionsmay 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 riverwater).
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Classification of matter
Mixtures:Variable composition. Components retain their characteristicproperties. May be separated into pure substances by physicalmethods (e.g. distillation). Mixtures of di�erent compositionsmay 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 riverwater).
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Compounds
Law of de�nite proportions: pure compounds always consist ofthe same elements combined in the same proportion by mass.
water 11.1 % hydrogen 88.9 % oxygencarbon dioxide 27.3 % carbon 72.7 % oxygen
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Compounds
Law of Multiple Proportions: If two elements form more than onecompound, in these compounds masses of one element thatcombine with a �xed mass of the other element are in a ratio ofinteger numbers.
N:ON2O 1:0.57NO 1:1.14 0.57:1.14=1:2NO2 1:2.28 0.57:2.28=1:4
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Foundations of Chemistry
Foundations of Chemistry
Atoms: the smallest particle of an element that maintains itschemical identity.
Structure of atoms:The diameter of an atom is ∼ 10−10 m (0.1 nm).The nucleus contains protons and neutrons. The diameter ofa nucleus is ∼ 10−15 m.
Particle Mass Chargeproton 1.672× 10−27 kg +1.602× 10−19 Cneutron 1.675× 10−27 kg noneelectron 9.109× 10−31 kg −1.602× 10−19 Cm(p+)m(e−) ≈ 1840
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Foundations of Chemistry
Atoms: the smallest particle of an element that maintains itschemical identity.Structure of atoms:
The diameter of an atom is ∼ 10−10 m (0.1 nm).The nucleus contains protons and neutrons. The diameter ofa nucleus is ∼ 10−15 m.
Particle Mass Chargeproton 1.672× 10−27 kg +1.602× 10−19 Cneutron 1.675× 10−27 kg noneelectron 9.109× 10−31 kg −1.602× 10−19 Cm(p+)m(e−) ≈ 1840
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Foundations of Chemistry
Atoms: the smallest particle of an element that maintains itschemical identity.Structure of atoms:
The diameter of an atom is ∼ 10−10 m (0.1 nm).The nucleus contains protons and neutrons. The diameter ofa nucleus is ∼ 10−15 m.
Particle Mass Chargeproton 1.672× 10−27 kg +1.602× 10−19 Cneutron 1.675× 10−27 kg noneelectron 9.109× 10−31 kg −1.602× 10−19 Cm(p+)m(e−) ≈ 1840
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Foundations of Chemistry
Atomic number (Z) = number of protons in the nucleus
Mass number (A) = number of protons + number of neutronsSymbol: AZX, 126CIsotopes: atoms for the same elements with di�erentmasses e.g 1
1H, 21H, 31HAtomic mass unit: exactly 1/12 of the mass of an atom of 126C(1 amu = 1.6606× 10−27 kg)On this scale the atomic weight of hydrogen is 1.00794 amu.Relative atomic mass: atomic weight divided by the atomicmass unitRelative atomic weight of hydrogen is 1.00794.
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Foundations of Chemistry
Atomic number (Z) = number of protons in the nucleusMass number (A) = number of protons + number of neutrons
Symbol: AZX, 126CIsotopes: atoms for the same elements with di�erentmasses e.g 1
1H, 21H, 31HAtomic mass unit: exactly 1/12 of the mass of an atom of 126C(1 amu = 1.6606× 10−27 kg)On this scale the atomic weight of hydrogen is 1.00794 amu.Relative atomic mass: atomic weight divided by the atomicmass unitRelative atomic weight of hydrogen is 1.00794.
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Foundations of Chemistry
Atomic number (Z) = number of protons in the nucleusMass number (A) = number of protons + number of neutronsSymbol: AZX, 126CIsotopes: atoms for the same elements with di�erentmasses e.g 1
1H, 21H, 31HAtomic mass unit: exactly 1/12 of the mass of an atom of 126C(1 amu = 1.6606× 10−27 kg)On this scale the atomic weight of hydrogen is 1.00794 amu.
Relative atomic mass: atomic weight divided by the atomicmass unitRelative atomic weight of hydrogen is 1.00794.
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Foundations of Chemistry
Atomic number (Z) = number of protons in the nucleusMass number (A) = number of protons + number of neutronsSymbol: AZX, 126CIsotopes: atoms for the same elements with di�erentmasses e.g 1
1H, 21H, 31HAtomic mass unit: exactly 1/12 of the mass of an atom of 126C(1 amu = 1.6606× 10−27 kg)On this scale the atomic weight of hydrogen is 1.00794 amu.Relative atomic mass: atomic weight divided by the atomicmass unitRelative atomic weight of hydrogen is 1.00794.
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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 electriccharge. Ions that possess a positive charge are calledcations. Those carrying negative charge are called anions.A radical is a group of atoms which have odd number ofelectrons.
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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 electriccharge. Ions that possess a positive charge are calledcations. Those carrying negative charge are called anions.
A radical is a group of atoms which have odd number ofelectrons.
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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 electriccharge. Ions that possess a positive charge are calledcations. Those carrying negative charge are called anions.A radical is a group of atoms which have odd number ofelectrons.
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Problems
What is the volume of a C atom if its radius is 77 pm?
V =43R
3π
V =43(77× 10
12m)3π
V = 1.91× 10−30 m3
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Problems
What is the volume of a C atom if its radius is 77 pm?
V =43R
3π
V =43(77× 10
12m)3π
V = 1.91× 10−30 m3
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Problems
A beaker weighed 53.10 g. To the beaker was added 5.348 g of ironpellets and 56.1 g of hydrochloric acid. What was the total massof the beaker and the mixture (before reaction)? Express theanswer to the correct number of signi�cant �gures.
Answer: 114.5 g
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Problems
A beaker weighed 53.10 g. To the beaker was added 5.348 g of ironpellets and 56.1 g of hydrochloric acid. What was the total massof the beaker and the mixture (before reaction)? Express theanswer to the correct number of signi�cant �gures.Answer: 114.5 g
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Problems
What is the number of protons, neutrons and electrons in a 23Naatom, in 1g of Na and in 1 mol of Na?
23Na atom: N(p+)=11, N(e+)=11, N(n+)=12
1g Na: N(atoms)= 1g23g/mol6× 10
23 = 2.61× 1022
N(p+)=11× 2.61× 1022=2.87× 1023N(e+)=11× 2.61× 1022=2.87× 1023N(n+)=12× 2.61× 1022=3.13× 1023
1 mol Na: N(atoms)=6× 1023N(p+)=11× 6× 1023=6.6× 1024N(e+)=11× 6× 1023=6.6× 1024N(n+)=12× 6× 1023=7.2× 1024
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Problems
What is the number of protons, neutrons and electrons in a 23Naatom, in 1g of Na and in 1 mol of Na?
23Na atom: N(p+)=11, N(e+)=11, N(n+)=12
1g Na: N(atoms)= 1g23g/mol6× 10
23 = 2.61× 1022
N(p+)=11× 2.61× 1022=2.87× 1023N(e+)=11× 2.61× 1022=2.87× 1023N(n+)=12× 2.61× 1022=3.13× 1023
1 mol Na: N(atoms)=6× 1023N(p+)=11× 6× 1023=6.6× 1024N(e+)=11× 6× 1023=6.6× 1024N(n+)=12× 6× 1023=7.2× 1024
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Problems
What is the number of protons, neutrons and electrons in a 23Naatom, in 1g of Na and in 1 mol of Na?
23Na atom: N(p+)=11, N(e+)=11, N(n+)=12
1g Na: N(atoms)= 1g23g/mol6× 10
23 = 2.61× 1022
N(p+)=11× 2.61× 1022=2.87× 1023N(e+)=11× 2.61× 1022=2.87× 1023N(n+)=12× 2.61× 1022=3.13× 1023
1 mol Na: N(atoms)=6× 1023N(p+)=11× 6× 1023=6.6× 1024N(e+)=11× 6× 1023=6.6× 1024N(n+)=12× 6× 1023=7.2× 1024
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Problems
What is the number of protons, neutrons and electrons in a 23Naatom, in 1g of Na and in 1 mol of Na?
23Na atom: N(p+)=11, N(e+)=11, N(n+)=12
1g Na: N(atoms)= 1g23g/mol6× 10
23 = 2.61× 1022
N(p+)=11× 2.61× 1022=2.87× 1023N(e+)=11× 2.61× 1022=2.87× 1023N(n+)=12× 2.61× 1022=3.13× 1023
1 mol Na: N(atoms)=6× 1023N(p+)=11× 6× 1023=6.6× 1024N(e+)=11× 6× 1023=6.6× 1024N(n+)=12× 6× 1023=7.2× 1024
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Problems
What is the charge of a Na+ ion and 1g of H+?
Na+ ion: Q(Na+) = +1.602× 1019C
1g H+: N = 1g1g/mol6× 10
23mol−1 = 6× 1023
Q = +1.602× 1019C× 6× 1023 = 9.612× 104C
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Problems
What is the charge of a Na+ ion and 1g of H+?
Na+ ion: Q(Na+) = +1.602× 1019C
1g H+: N = 1g1g/mol6× 10
23mol−1 = 6× 1023
Q = +1.602× 1019C× 6× 1023 = 9.612× 104C
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Problems
What is the charge of a Na+ ion and 1g of H+?
Na+ ion: Q(Na+) = +1.602× 1019C
1g H+: N = 1g1g/mol6× 10
23mol−1 = 6× 1023
Q = +1.602× 1019C× 6× 1023 = 9.612× 104C
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Problems
What is the atomic weight of magnesium according to the abovedata?
Isotope % Abudance Mass (amu)24Mg 78.99 23.98525Mg 10.00 24.98626Mg 11.01 25.983
Atomic weight of magnesium=0.7899× 23.985+ 0.1000× 24.986+ 0.1101× 25.983 = 24.30amu
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Problems
What is the atomic weight of magnesium according to the abovedata?
Isotope % Abudance Mass (amu)24Mg 78.99 23.98525Mg 10.00 24.98626Mg 11.01 25.983
Atomic weight of magnesium=0.7899× 23.985+ 0.1000× 24.986+ 0.1101× 25.983 = 24.30amu
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Problems
What is the atomic weight of magnesium according to the abovedata?
Isotope % Abudance Mass (amu)24Mg 78.99 23.98525Mg 10.00 24.98626Mg 11.01 25.983
Atomic weight of magnesium=0.7899× 23.985+ 0.1000× 24.986+ 0.1101× 25.983 = 24.30amu
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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 ofcocaine?
C 67.3012 = 5.608
H 6.931 = 6.93
O 21.1516 = 1.322
N 4.6214 = 0.33
C 5.6080.33 = 17
H 6.930.33 = 21
O 1.3220.33 = 4
N 0.330.33 = 1
C12H21O4N
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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 ofcocaine?
C 67.3012 = 5.608
H 6.931 = 6.93
O 21.1516 = 1.322
N 4.6214 = 0.33
C 5.6080.33 = 17
H 6.930.33 = 21
O 1.3220.33 = 4
N 0.330.33 = 1
C12H21O4N
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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 ofcocaine?
C 67.3012 = 5.608
H 6.931 = 6.93
O 21.1516 = 1.322
N 4.6214 = 0.33
C 5.6080.33 = 17
H 6.930.33 = 21
O 1.3220.33 = 4
N 0.330.33 = 1
C12H21O4N
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Quiz
Which one of the following is an example of a chemical change?
A. Mixing sand and sugarB. Cutting a piece of paper into two piecesC. Ice melting to waterD. Burning a piece of paper to form carbon dioxide and waterE. Mixing water and orange juice
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Quiz
Which of the following is an example of a solution?
A. WaterB. A combination of red and white chalk dustC. Carbon disul�de (a chemical combination of carbon andsulfur)D. AluminumE. Sugar water
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Quiz
Which of the following are substances?
A. Elements and solutionsB. Elements and compoundsC. Heterogeneous mixtures onlyD. Heterogeneous mixtures and solutionsE. Elements only
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Quiz
Which one of the following is an extensive property?
A. TemperatureB. MassC. TasteD. DensityE. Color
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Quiz
Which one of the following is a chemical change?
A. Iron �lings are separated from sand using a magnetB. Liquid nitrogen boils to become nitrogen gasC. Gunpowder is explodedD. Antifreeze is added to water in an automobile radiatorE. A shaken cola can is opened producing a spray of soda andcarbon dioxide gas
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Quiz
Which of the following converts chemical energy to mechanicalenergy?
A. A waterwheelB. A kerosene heaterC. A gasoline-powered automobile engineD. A battery attached to a light bulbE. A solar oven
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Problems
When a mixture of aluminum powder and iron(III) oxide isignited, it produces molten iron and aluminum oxide. In anexperiment, 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 ofiron, 10.20 g of aluminum oxide, and an undetermined amount ofunreacted iron(III) oxide. No aluminum was left. What is themass of the iron(III) oxide?
Answer: 2.53 g
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Problems
When a mixture of aluminum powder and iron(III) oxide isignited, it produces molten iron and aluminum oxide. In anexperiment, 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 ofiron, 10.20 g of aluminum oxide, and an undetermined amount ofunreacted iron(III) oxide. No aluminum was left. What is themass of the iron(III) oxide?Answer: 2.53 g
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