Chem 1441 Exam 1 Study Guide Lectures Ch 1 2 and Ch 3 section 3 Chapter 1 Keys to the Study of Chemistry Significant Figures We want to know the quantification How much Exact Numbers they do not limit the number of sig figs Counted objects such as a dozen eggs 12 or 4 pencils Inexact any measurement quantity Ex graduated cylinder beaker thermometer weight scale Some conversion factors are exact by definition such as 1000g 1kg 12in 1ft we use sig figs to determine the accuracy and precision 2 54 cm 1in Some numbers are exact and some are inexact Significant Figures Rules 1 Non zero digits are always significant 2 3 4 5 6 of sig figs 7 45 3 2874 4 Zeros between nonzero digits are significant 7 02 3 2 006 4 Zeros at the beginning are never significant 0 000265 3 0 0002006 4 Zeros at the end are only significant if the decimal is present 7 00 3 20 000 5 0 04050 4 140 3 Final zeros in a number with no decimal points are ambiguous 230 2 4000 1 Scientific Notation is used to get rid of the ambiguity Express 1800 in three sig figs 1 80 x103 Express 5000 to two sig figs 9 0 x103 Significant Figures Practice Problems How many significant figures are 1 2 3 4 27 038 g 3 0 x 1023 atoms 0 002050 cm3 4 450 ft Answers in each of the following measurements 1 5 2 2 3 4 4 3 Significant 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 22 2 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 0 3 When doing mixed calculations Do the calculations one step at a time applying the appropriate rule at each step Ex 12 3 8 72 295 7 1 4105505 295 7 297 1105505 297 1 Significant 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 29 2 22 34 5 6 7 9 74 10 3 2 33 9 1 3 55 1 2 4 9 SI Units Know the table below Physical Quantity Unit Abbreviation Mass kilogram kg Length meter m Time second s Electric current ampere A Temperature Kelvin K Luminous intensity candela cd Amount of substance mole mol Answers Metric Prefix Practice Problems 1 2 3 4 5 6 7 8 9 10 11 12 13 What What What What What What What What What What What What What is is is is is is is is is is is is is the the the the the the the the the the the the the meaning for deci meaning for mega symbol for milli meaning for micro symbol for kilo meaning for centi symbol for pico symbol for giga meaning for tetra symbol for femto meaning for milli symbol for nano meaning for giga 1 10 1 2 10 6 3 m 4 10 6 5 k 6 10 2 7 p 8 G 9 10 12 10 f 11 10 3 12 n Temperature Unit Practice Problems Use the temperature conversions to solve 1 Convert 65 0F to Celsius 18 0C 2 Convert 25 0C to Kelvin 248 K 3 Convert 525 K to 0C 252 0C Dimensional Analysis Practice Problems 1 2 3 4 5 If an object has a mass of 115 lbs what is its mass in grams 52 200 g How many feet are in 6 0 yards 18 ft How many yards are in 6 0 feet 2 0 yd Convert 0 00275 dL to L 275 L Express 65 miles hr in m s given 1 mi 1 609 km 29 1 m s Density mass volume Solve 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 mL Chapter 2 Elements Compounds and Mixtures 1 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 ion negatively charged ion an1 Ex H 1 008 2 Isotopes atoms of the same element that differ from each other only by the of the neu trons EX C C 12 13 14 C 23 Na P3 31 protons 6 6 6 11 15 neutrons 6 7 8 12 16 electrons 6 6 6 10 18 3 Molecules molecular mass Molecular Compounds 2 NON metals 4 Ionic Compounds naming A metal Non metal 5 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 Sn 7 Acids naming 8 Mass Percent calculations Practice problems Worksheet An element has 2 isotopes the first with a mass of 10 and a relative abundance of 19 8 the second with a mass of 11 and a relative abundance of 80 2 Calculate the average atomic mass of this element and identify it 10 802 B 2 What is Aluminum s atomic number 13 3 Determine if the compounds below are ionic of molecular 1 PCl3 molecular MgBr2 ionic KF ionic CS2 molecular HBr molecular 4 Give the formulas for the Polyatomic ions ionic and molecular compounds and Acids refer notes Names Mercury II Acetate Hydronium Nitrite Iodate Perbromate Hydrogen Phosphate Sulfite Cynide Dichromate Ammonium Mercury I Phosphate Permanganate Thiosulfate Sulfite Dihydrogen Phosphate Periodate Hydrogen Carbonate Peroxide Permanganate Azide Bromide Formula Iodate Sodium Peroxide Ammonium Sulfate Calcium Carbonate Acidic Acid Nitric Acid Potassium Chloride Silver Sulfate Sulfur Trioxide DiNitrogen Pentaoxide Sulfurous Acid Hydrocyanic Acid Mercury I Chloride Chapter 3 Balancing Equations balance the following equations 1 Al HCl AlCl3 H2 2 Al 6 HCl 2 AlCl3 3 H2 2 Write the balance equation for a complete combustion of ethane C2H6 in oxygen 2 C2H6 7 O2 4 CO2 6 H2O