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QUALITATIVE VS. QUANTITATIVE QUALITATIVE = DESCRIPTIVE, NON- NUMERICAL. EX. : THE MORNINGS ARE GETTING VERY COLD. QUANTITATIVE = NUMERICAL, DEFINITE MEASUREMENT EX. : THE TEMPERATURE WAS 65°F THIS MORNING.
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Know your metric relationships! kilo -hecta - deca -(base) - deci - centi – milli ( 10 3 - 10 2 -10 1 - (1) – 10 -1 - 10 -2 - 10 -3 ) K ing H enry D ied B y D rinking C hocolate M ilk
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In science, we deal with some very LARGE numbers: 1 mole = 602000000000000000000000 In science, we deal with some very SMALL numbers: Mass of an electron = 0.000000000000000000000000000000091 kg Scientific Notation
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Imagine the difficulty of calculating the mass of 1 mole of electrons! 0.000000000000000000000000000000091 kg x 602000000000000000000000 x 602000000000000000000000 ???????????????????????????????????
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Scientific Notation: A method of representing very large or very small numbers in the form: M x 10 n M x 10 n M is a number between 1 and 10 n is an integer
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2 500 000 000 Step #1: Insert an understood decimal point. Step #2: Decide where the decimal must end up so that one number is to its left up so that one number is to its left Step #3: Count how many places you bounce the decimal point the decimal point 1234567 8 9 Step #4: Re-write in the form M x 10 n
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2.5 x 10 9 The exponent is the number of places we moved the decimal.
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0.0000579 Step #2: Decide where the decimal must end up so that one number is to its left up so that one number is to its left Step #3: Count how many places you bounce the decimal point the decimal point Step #4: Re-write in the form M x 10 n 12345
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5.79 x 10 -5 The exponent is negative because the number we started with was less than 1.
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Rules for using scientific notation Numbers are represented as a value between 1 <10 Exponents (+),(-) describe the decimal movement (+) number grows larger (-) number gets smaller Ex: 1.2 x 10 3 = 1200 Math function and scientific notation: Be sure to use the [2 nd ][EE] function on your calculator! Ex. 5.0 3 x 10 14 / 2.9 x 10 7 = ?
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Standard Unit of measure Metric based measurements Length = meter (m) Mass = kilograms (kg) Time = seconds (s) Temperature = Kelvin (K) Amount of substance = mole (mol) Electric Current = ampere (A)
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QuantitySymbolAbbrev.Definition Length l m Length light path in 3.0 x 10 8 s (speed of light m/s) MassmkgBased on standard mass Timets Atomic clock: Based on Ce-133 isotope (clock-based on frequency of energy as electrons transition between orbitals) TemperatureTK kelvin: 0 K is absolute zero (no molecular movement. Triple pt. water = 273.15K AmountNmol Mole: amt of substance equivalent to 12g C-12. (Avogadro’s # 6.023 x 10 23 ) Electric CurrentlA Measures the amt. of electric charge passing a pt. in a electric circuit/time (Coulomb/s )
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Atomic clock
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Temperature:
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Measurement produced by multiplying or dividing SI units. quantitysymb ol Abbrev.Derivation AreaAm2L x W VolumeVm3L X W X H DensityD g/cm3 (mL) Mass/volume Molar massM g/mole Mass/ amt. of substance Molar volume VmVm m3/mole Volume. /amt. of a substance EnergyEJoulesForce X Length
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The amount of space occupied by an object Some useful relationships: 1Liter = 1dm 3 = 10 3 cm 3 = 1000mL 1cm 3 = 1mL
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Volume:
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Describes the ratio of mass to volume Density is a physical property that is independent to amount ( intensive property ) D = Mass/Volume= (g/mL or g/cm 3 )
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Measuring density: Solids - Liquids Displacement
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Calculations using density: Conversions using density: Ex. Aluminum has a density of 2.699 g/cm3 What is mass of a 11.25 cm3 block of Al? 11.25 cm 3 2.699 g= 30.36 g Al 1cm 3 What is the volume of a 3. 75g sample of Al? 3.75 g Al 1cm 3 = 1.38 cm 3 2.699g
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A relationship showing the equality between two different units that allows for conversion between these units. Examples: 1 week = 7 days 1 dozen eggs = 12 eggs ???
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Accuracy - close to the true value Precision - close within measurements % Error- describes how close your data is to the accepted value Accepted – Experimental x 100 Accepted Value
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Accuracy & Precision
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Used to express the accuracy of a number. Used for “measured” numbers. Rules for determining Sig. Figs. 1. All non-zero numbers are significant 2. Captive zeros are significant 3. Leading zeros are not significant 4. Trailing zeros are significant if a decimal is present
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Significant figures: Determine the number of sig figs 1. 3060 2..000789 3. 1.40 x 10 6 4. 1000 5. 2030. 6. 45,0060
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Answers: Determine the number of sig figs 1. 3060 (3) 2..000789 (3) 3. 1.40 x 10 6 (3) 4. 1000 (1) 5. 2030. (4) 6. 45,0060 (5)
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Addition/Subtraction Limited to the placement of the least significant figure. ex. 12.00 + 8.3 + 14 = Multiplication/Division Limited to the lowest number of significant figures. Ex. 12.0 x 8.3 X 14 =
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Let’s set up a problem: What is the mass of a block of gold that has a volume of 2.0 cubic inches? 98 grams.. Worth $4,520.00!
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Problem Solving Steps to Problem Solving Approach: A. Analyze: determine starting point and plan steps required to get a solution (unknown). B. Plan: set up a strategy to solve the problem. C. Solve: conduct appropriate calculations based on plan. This may require multiple steps. D. Evaluate: Review answer to see if it seems reasonable.
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Problem Solving Conversion Factors - a ratio of equivalent measurements ( 1 inch = 2.54 cm) Dimensional Analysis- the technique for solving problems using unit conversions based on conversion factors Ex. 6. 42 inches = ? cm
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Problem Solving Multi-step Problems – use more than one conversion factor: ex. 5 days = ? minutes Complex Problems- involves ratios of two units: ex..45 Km/hrs = ? m/s Golden Rule for conversions…always show your work!
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