Measurement/Calculation Units of Measure

Metric System based on powers of ten, so it’s easy to convert between units. Remember: KING HENRY DANCED BEFORE DAWN COUNTING MONEY Or KING HENRY DIED BY DRINKING CHOCOLATE MILK

Units Mega kilo hecto deka BASE deci centi milli micro M k h da (none)  106 105 104 103 102 101 100 or 1 10-1 10-2 10-3 10-4 10-5 10-6

How to use Right Kilo Hecto Deka BASE Deci Centi Milli Left

Examples 20 L= _______ mL 7 kg = _______ mg 90 mm = _______ cm Kilo Hecto Deka BASE Deci Centi Milli 20 L= _______ mL 7 kg = _______ mg 90 mm = _______ cm 223 mL = ________ L 0.49 hm = ______ m 20 000 7 000 000 9.0 0.223 49

SI base units Quantity Base Unit Symbol Time second s Length meter m Mass kilogram kg Temperature Kelvin K Amount of a substance mole mol

SI derived units (derived units are calculated from base units) Quantity Derived Unit Symbol Volume: various formulas, such as LxWxH cubic centimeters or milliliters liters cm3 or mL L Density: mass divided by volume grams per milliliter or grams per cubic centimeter g/mL or g/cm3

NOTE: 1 cm3 IS EQUAL TO 1 mL!!! And a cc is the same as a cm3

Measurement/Calculation Scientific Notation/Accuracy &Precision

Rules to putting into Sci Not Must have a whole number between 1- 9 If you move: Decimal to Left…exponent is Positive Decimal to Right...exponent is Negative

Examples .0032 15 300 000 3.2 X 10-3 1.53 X 107

Examples 5.00 X 104 2.32 X10-3 50 000 5.00 .00232 2.32

Addition/Subtraction Make exponents the same by moving decimal place and changing exponent Then add/subtract and put in correct Sci Not OR Type into your calculator Change mode to Sci

Example 5.00 X 104 + .244 X 104 5.00 X 104 + 2.44 X 103  5.244X 104 OR Type into your calculator EXP EE EXP EE Enter 5.00 4 3 + 2.44

Multiplication/Division Multiply numbers Add exponents Division Divide numbers Subtract exponents Then put back in correct scientific notation!

Example = 6.7 × 102 g/mol Type on your calculator: = 671.6049383 =0.67 X 103 g/mol Type on your calculator: EXP EE EXP EE ENTER EXE 5.44 7 ÷ 8.1 4 = 671.6049383 = 670 g/mol = 6.7 × 102 g/mol

Accuracy and Precision Accuracy: how close a measurement is to the true value (the “correct answer”) Precision: how close a value is to other values in that series

Are the following groups of measurements accurate, precise, both, or neither? 1) Given: true mass of sample of zinc is 14.5 g Measurements made: 13.2 g, 15.6 g, 17.9 g, 12.0 g Given: true volume of sample of water is 33.3mL 22.4 mL, 22.2 mL, 22.4 mL, 22.3 mL 3) Given: true length of copper wire is 58.5 cm 58.4 cm, 58.5 cm, 58.5 cm, 58.4 cm

Quantitative: a numerical measurement (quantity) Qualitative: a descriptive measurement (quality); does not involve numbers Quantitative: a numerical measurement (quantity)

Measurement/Calculation Significant Figures

Rules to Significant Figures If it’s not 0, it counts. Example 743.44 24 5 2

Rules to Significant Figures 0’s in between significant figures count. Example 506 20405 .707 3 5 3

Rules to Significant Figures All 0’s at the end past the decimal point count. Example 2.440 784.30 4 5

Rules to Significant Figures 0’s as placeholders don’t count. Example 440 0.09 2 1

Alternative Way Atlantic (Absent) Pacific (Present)

Pacific (Present) Atlantic (Absent) If the decimal is present, start on the Pacific side at the first nonzero digit and count it and all the digits to the right of it. If the decimal is absent, start on the Atlantic side at the first nonzero digit and count it and all the digits to the left of it.

Adding/Subtracting Add/Subtract First The answer has only as many decimal places as the measurement having the least number of decimal places. Example 190.2 g 65.291 g 12.38 g 267.871 g 1 3 2 267.9 g Answer should have 1 decimal place

Multiplication/Division Mult/Divide First The answer has only as many significant figures as the measurement with the least number of significant figures. Example 13.78 g 11.3 mL 4 3 1.22 g\ml = 1.219469 g/mL Answer should have 3 significant figures

Example 15000 2030.0 0.0020 2 5

Measurement/Calculation Density

Density Derived unit g/mL or g/cm3 Mass/Volume

D. Density V = 825 cm3 m = DV D = 13.6 g/cm3 m = (13.6 g/cm3)(825cm3) An object has a volume of 825 cm3 and a density of 13.6 g/cm3. Find its mass. GIVEN: V = 825 cm3 D = 13.6 g/cm3 m = ? WORK: m = DV m = (13.6 g/cm3)(825cm3) m = 11 220 g=11 200g

D. Density D = 0.87 g/mL V = m V = ? m = 25 g V = 25 g 0.87 g/mL A liquid has a density of 0.87 g/mL. What volume is occupied by 25 g of the liquid? GIVEN: D = 0.87 g/mL V = ? m = 25 g WORK: V = m D V = 25 g 0.87 g/mL V = 28.74mL = 29 mL

D. Density D = ? D = m V = 53.4-50 =3.4 mL m = 5.6 g D = 5.6 g 3.4 mL A marble has a mass of 5.6 g. It is placed in a graduated cylinder with 50.0 mL of water. The water level rises to 53.4 mL. What is the density of the marble? 3.4 mL GIVEN: D = ? V = 53.4-50 =3.4 mL m = 5.6 g WORK: D = m V D = 5.6 g 3.4 mL D=1.647 g/mL = 1.6 g/mL

Graphing Graphing is an important tool for expressing data so that it is easier to read and interpret Rules for graphing: --place the manipulated/independent variable (the one that was changed) on the x axis. --place the dependent/responding variable (the results of that change) on the y axis. (dry mix) DRY MIX y scale = largest y value – smallest y value x scale = largest x value – smallest x value # of lines on the y axis # of lines on the x axis The graph should cover at least ¾ of the grid