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# UT Arlington CHEM 1441 - Exam 1 Study Guide

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Chem 1441Exam # 1 Study Guide Lectures: Ch.1-2, and Ch.3 section 3Chapter 1: Keys to the Study of ChemistrySignificant Figures:-We want to know the quantification. How much?-Some numbers are exact and some are inexactSignificant Figures Rules:1. Non-zero digits are always significant: # of sig figs.7.45 32874 42. Zeros between nonzero digits are significant7.02 32.006 43. Zeros at the beginning are never significant0.000265 30.0002006 44. Zeros at the end are only significant if the decimal is present:7.00 320.000 50.04050 4140. 35. Final zeros in a number with no decimal points are ambiguous:230 24000 16. Scientific Notation is used to get rid of the ambiguity:Inexact:-any measurement quantity-Ex: graduated cylinder, beaker, ther-mometer, weight scale-we use sig figs to determine the ac-curacy and precisionExact Numbers: (they do not limit the number of sig figs.)-Counted objects such as a dozen eggs (12) or 4 pen-cils-Some conversion factors are exact by definition such as:• 1000g = 1kg• 12in = 1ft•2.54 cm = 1in.-Express 1800 in three sig figs: 1.80 x103-Express 5000 to two sig figs: 9.0 x103Significant Figures Practice Problems:How many significant figures are in each of the following measurements?1. 27.038 g2. 3.0 x 1023 atoms3. 0.002050 cm34. 4,450 ftSignificant figures for Calculations:-Rules: (answers are in red)1. Multiplication & Division:- Answer has to have the amount of sig figs as the number with the least sig figs.- Ex: 2.99 x 7.3 = [21.827] = 222. Addition & Subtraction:-Answer has to have the same number of decimal places as the least precise measurement used in the calculations.-Ex: 29.52 + 3.001 + 7219.5 = [7252.021] = 7252.03. When doing mixed calculations:-Do the calculations one step at a time, applying the appropriate ruleat each step-Ex: 12.3/8.72 + 295.7 = 1.4105505 + 295.7 = [297.1105505] = 297.1Significant Figures Calculation Practice Problems:Complete the following calculations and round answers off to the correct sig figs.1. 5.670 x 0.051 = [0.28917] = 0.292. 22.34 - 5.6 - 7 = [9.74] = 103. (2.33 +9.1) / (3.55 - 1.2) = 4.9Answers:1) 52) 23) 44) 3SI Units: (Know the table below)Physical Quantity Unit AbbreviationMass kilogram kgLength meter mTime second sElectric current ampere ATemperature Kelvin KLuminous intensity candela cdAmount of substance mole molMetric Prefix Practice Problems:1. What is the meaning for deci?2. What is the meaning for mega?3. What is the symbol for milli?4. What is the meaning for micro?5. What is the symbol for kilo?6. What is the meaning for centi?7. What is the symbol for pico?8. What is the symbol for giga?9. What is the meaning for tetra?10. What is the symbol for femto?11. What is the meaning for milli?12. What is the symbol for nano?13. What is the meaning for giga?Temperature Unit Practice Problems: (Use the temperature conversionsto solve)1. Convert 65 0F to Celsius = 18 0CAnswers:1. 10^-12. 10^63. m4. 10^-65. k6. 10^-27. p8. G9. 10^1210. f11. 10^-312. n2. Convert -25 0C to Kelvin = 248 K3. Convert 525 K to 0C: 252 0CDimensional Analysis Practice Problems:1. If an object has a mass of 115 lbs, what is its mass in grams? 52,200 g2. How many feet are in 6.0 yards? 18 ft.3. How many yards are in 6.0 feet? 2.0 yd4. Convert 0.00275 dL to μL. 275 μL5. Express 65.miles/hr in m/s. (given 1 mi = 1.609 km): 29.1 m/sDensity = mass/volumeSolve using the density formula as a conversion factor:1. What volume will be occupied by a 83.5 gram sample of Copper (Cu) if its density is 8.96 g/mL? 9.32 mLChapter 2: Elements, Compounds and Mixtures1. Atomic Structure:-Proton: positively charged particle in nucleus, 1 amu-Neutron: negatively charged particle-Electron: negatively charged particle in electron cloud-ions: different protons and electrons-cation: positively charged ion-an- ion: negatively charged ion-Ex:2. Isotopes:-atoms of the same element that differ from each other only by the # of the neu-1H1.008trons-EX: 12C13C14C23Na+ 31P3-protons 6 6 6 11 15neutrons 6 7 8 12 16electrons 6 6 6 10 183. Molecules:-molecular mass-Molecular Compounds: 2 NON-metals4. Ionic Compounds (naming)- A metal + Non-metal5. Elements Compounds (naming)6. Periodic Table: Know where to find-Atomic #-mass number-period-group-metal vs. nonmetal vs. metalloid-solids vs. liquids vs. gas-radioactive elements-first 36 elements as well as: Ag, Au, Hg, Pb (lead) Xe, W, Pt, Sn7. Acids (naming)8. Mass Percent (calculations)Practice problems Worksheet:1. An element has 2 isotopes, the first with a mass of 10 and a relative abundanceof 19.8%, the second with a mass of 11 and a relative abundance of 80.2. Calcu-late the average atomic mass of this element and identify it.10.802 = B2. What is Aluminum’s atomic number? 133. Determine if the compounds below are ionic of molecular.PCl3molecularMgBr2ionicKFionicCS2molecularHBrmolecular4. Give the formulas for the Polyatomic ions, ionic and molecular compounds, and Acids: (refer notes)Names FormulaMercury(II)AcetateHydroniumNitriteIodatePerbromateHydrogen PhosphateSulfiteCynideDichromateAmmoniumMercury(I)PhosphatePermanganateThiosulfateSulfiteDihydrogen PhosphatePeriodateHydrogen CarbonatePeroxidePermanganateAzideBromideIodateSodium PeroxideAmmonium SulfateCalcium CarbonateAcidic AcidNitric AcidPotassium ChlorideSilver SulfateSulfur TrioxideDiNitrogen PentaoxideSulfurous AcidHydrocyanic AcidMercury(I) ChlorideChapter 3: Balancing Equations: (balance the following equations)1. Al + HCl —> AlCl3 + H22 Al + 6 HCl —> 2 AlCl3 + 3 H22. Write the balance equation for a complete combustion of ethane, C2H6 in oxy-gen.2 C2H6 +7 O2 —> 4 CO2 + 6

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