# CHEM 1305 Ch.2 Units and Conversions.pdf - CHAPTER 2...

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CHAPTER 2 LECTURE OUTLINEUnits &Conversion1
2.4 UNITS2The number ismeaninglesswithout the unit.Proper aspirin dosage = 325 (milligrams or pounds?)A fast time for the 100-meter dash = 10.00 (seconds or days?)Every measurement is composed of anumberand aunit.Examples:
UNIT CONVERSIONSThere are two main systems used in the world for measurement:1.English System2.Metric SystemSLO 23(accessed 8.3.17)
UNIT CONVERSIONSENGLISH SYSTEMWe use miles, gallons, pounds, inches, yards, etc.12 inches in a foot3 feet in a yard*On exams I will provide a list of conversion factorsSLO 2. 14
UNIT CONVERSIONSMETRIC SYSTEMUsed almost everywhere else on the planet earthEach type of measurement (e.g. length, mass, volume) has a base unitAny other derivative of that type of measurement is related by a power of 10We can use prefixes to understand how that measurement relates to the base unitSLO 2.25Memorize This TableQuantityMetric Base UnitSymbolLengthMetermMassGramgVolumeLiterLTimeSecondsTemperatureKelvinKAmount of substancemolemol
6Theprefixof the unit name indicates if the unit islargerorsmallerthan the base unit.Memorize This Table
2.4 MEASUREMENTA. MEASURING MASS71kilogram (kg) =1,000grams (g)1 kg = 1,000 g1milligram (mg) =0.001grams (g)1 mg = 0.001 g1centigram (cg) =0.01grams (g)1 cg = 0.01 gThebase unit of massis thegram(g).Massis a measure of theamount of matter in anobject.Weightis the force thatmatter feels due to gravity.
2.4 MEASUREMENTB. MEASURING LENGTH81kilometer (km) =1,000meters (m)1 km = 1,000 m1millimeter (mm) =0.001meters (m)1 mm = 0.001 m1centimeter (cm) =0.01meters (m)1 cm = 0.01 mThebase unit of lengthis themeter(m).
2.4 MEASUREMENTC. MEASURING VOLUME91kiloliter (kL) =1,000liters (L)1 kL = 1,000 L1milliliter (mL) =0.001liters (L)1 mL = 0.001 L1centiliter (cL) =0.01liters (L)1 cL = 0.01 LThebase unit of volumeis theliter(L).Volume = Length x Width x Height= cm x cm x cm= cm31 mL = 1 cm3= 1 cc
PICK THE LARGER OF THE PAIRSMetric1 m / 1 cm10 millimeter / 1 centimeter1000 L / 1000 mL20 g / 20 kg3 liters / 3 deciliters1000 mg / 1 gEnglish1 ft / 1 in1 oz / 1 lb1 gal / 4 qtsSLO 2.2 / 2.310
MATCH THE TERMS1)Metric unit of mass2)Liquid3)1000 times larger than ameter4)Metric unit of volume5)Mass6)Weight7)Solid8)1/100 of a meterA.Amount of matter in an objectB.Definite volume and shapeC.cmD.Force of gravity on an objectE.GramF.Definite volume, indefinite shapeG.LiterH.kmSLO 1 AND 211
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SIGNIFICANT FIGURES (SIG-FIGS)Exactnumbers:Numbers we know exactlyThere are 12 eggs in a dozenNumbers we use to define a quantityThere are 12 inches (in) in 1 foot (ft)1 inch is 2.54 cm1 g is 0.001 kgInexact Numbers: Numbers from a measurementContains some level of uncertainty.

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