Chemistry & Chemical ReactivityKotz, Treichel, Townsend

Note About Math & Chemistry

Units of Measure

Units of Measure

Temperature Units

Temperature ConversionConvert F to C TC = 5/9 ( TF 32.00 )

Convert C to K TK = TC + 273.15

Length, Volume, and Mass

Energy Units

Making Measurements: Precision

Making Measurements: Accuracy

Making Measurements: Standard Deviation

Mathematics of Chemistry

1.23 104Coefficient or Mantissa (this number is 1 and

Mathematics of Chemistry

Counting Significant Figures

Determining Significant FiguresDetermine the number of Sig. Figs. in the following numbers4 sf7 sf3 sf5 sf3 sf4 sf 4 sf1256 10560070.0003450.000469090.080401780770.0

Rounding Numbers

110000010560070.00034517800.000351800Rounding Numbers

Sig. Figures in Calculations

23.50 0.2001 174 sf4 sf2 sf = 1996.50174910 sfYour calculator knows nothing of sig. fig. !from the calculator:Sig. Figures in Calculations

Sig. Figures in Calculations

391 12.6 + 156.1456Sig. Figures in Calculations

391 12.6 +156.145639112.6+156.1456Sig. Figures in Calculations

534.5456(answer from calculator)Answer: 535Sig. Figures in Calculations

Sig. Figures in Calculations

1st determine the correct # of sf in the numerator (top)2nd determine the correct # of sf in the denominator (bottom)The result will be limited by the least # of sf (division rule) Sig. Figures in Calculations

26.05+ 32.10.0032+ 7.7The result may only have 2 sfSig. Figures in Calculations

7.703258.150= 7.5488= 7.52 sfCarry all of the digits through the calculation and round at the end.Sig. Figures in Calculations

Problem Solving and Chemical Arithmetic

Problem Solving and Chemical Arithmetic

Problem Solving and Chemical Arithmetic

Exact Conversion Factors: CF in the same system of units, and CF determined by definitionUse of exact CFs will not affect the significant figures in a calculation, because exact CFs contain an infinite number of SFsExamples of Conversion Factors 1 m 100 cm 1 inch 2.54 cm 1 mile 5280 feet

1.000 kg = 2.205 lbSI unitsBritish Std.Use of inexact CFs will affect significant figures.(4 sig. figs.)Inexact Conversion Factors: CF that relate quantities in different systems of unitsExamples of Conversion Factors

Problem Solving and Chemical Arithmetic

Problem Solving and Chemical Arithmetic

Problem Solving and Chemical Arithmetic

First: Outline of the conversion:m miles ft in cm Each arrow indicates the use of a conversion factor.Problem Solving and Chemical Arithmetic

Problem Solving and Chemical Arithmetic

Problem Solving and Chemical Arithmetic////////

Fourth: Now use your calculator:Problem Solving and Chemical ArithmeticCarry though all digits, round at end2.01168 x 105 m Round to: 2.01 x 105 (3 sf)

Problem Solving and Chemical Arithmetic

Problem Solving and Chemical Arithmetic

Problem Solving and Chemical Arithmetic

Problem Solving and Chemical Arithmetic3 sf

Map out your conversion:ft3 ////8.96993 10-4 ft3=cm3 in3 Round to: 8.97 10-4 ft3 (3 sf)exactexactProblem Solving and Chemical Arithmetic3 sf

Problem Solving and Chemical Arithmetic

Optional SlideInstructor Note: Each individual component to this slide may be brought in on unit at a time using the custom animation tools in PowerPoint.Instructor note: Each individual component to this slide may be brought in on unit at a time using the custom animation tools in PowerPoint.