Presentation on theme: "Measurement & Conversions"— Presentation transcript:
1 Measurement & Conversions Get ready for some math!!!!
2 Scientific Notation Used for very large or very small numbers All numbers are represented by a number between 1 and 10 multiplied by a power of 10The number of places the decimal point has moved determines the power of 10.If the power is positive, the decimal point will move to theIf the power is negative, the decimal point will move to the left
3 MeasurementMeasurements and calculations allow for some of the properties of substances to be determined (mass, density)Scientific Notation is often used because measurements in chemistry can be very large or very small
4 Convert the following numbers to scientific notation 245003560.22212200
5 Convert the following scientific notation numbers to regular numbers 4.2 x 1032.15 x 10-43.14 x 10-69.22 x 1059.57 x 102
6 Significant FiguresAll measured quantities are generally reported in a way that the last digit is UNCERTAIN.All other digits are considered SIGNIFICANT.
7 Rules for Sig Figs Nonzero digits are always significant. 22.6 kg has 3 significant figures453.9 m has 4 sig figsZeros between nonzero digits are significant.20.3 kg has 3 sig figs87009 L has 5 sig figs
8 Rules for Sig Figs cont’d Zeros in front of nonzero digits are not significant (they simply are decimal place holders)has 4 sig figshas 1 sig figZeros both at the end of a number and to the right of a decimal point are significant85.00 kg has 4 sig figshas 11 sig figs
9 Rules for Sig Figs cont’d Zeros both at the end of a number but to the left of a decimal point may not be significant. If a zero has not been measured or estimated, it is NOT SIGNIFICANT. A decimal point placed after zeros indicates that the zeros are significant.2000 m has one significant figure2000. m has four sig figs
10 Rules for Calculations Multiplication or Division –Final answer has the smallest # of sig figsDO NOT ROUND UNTIL THE VERY END.Addition or Subtraction –Result cannot have more decimals places than the unit with the smallest # of decimal places
11 Rules for Calculations If a calculation has both multiplication (or division) and addition/subtraction, round after each operation.EXACT VALUES HAVE UNLIMITED SIG FIGS2 MOLECULES ARE 2 MOLECULES. = COUNT VALUE
12 SI Units Measurement Symbol Unit Abbreviation Length l meter m Mass M kilogramkgTimetsecondsTherm. TempTkelvinKAmount of substancenmolemol
13 Prefixes Prefix Symbol Meaning Mega M 106 Kilo K 103 Deci D 10-1 Centi 10-2Milli10-3Microm10-6
17 Conversion FactorsA ratio that is derived from the equality of two different units that can be used to convert from one unit to the other5 dozen eggs = how many individual eggs?CONVERSION FACTOR1 dozen = 12 individual5 dozen x 12 individual = 60 individual eggs1 dozen
20 Derived Units Units derived from the seven base units Volume= l x w x h (m3)VolumeThe most common used unit for volume is cm3.1cm3 = 1ml1000cm3 = 1dm3 = 1000ml = 1L.densityDensity is the ratio of the mass of an object to its volumeDensity = massvolume
21 Precision vs. AccuracyAccuracy- the accuracy of a measurement is how close the measurement is to the true or actual valuePrecision – is how closely several measurements made agree with one another.