chemistry september 30, 2014 si/significant figures/scientific notations
TRANSCRIPT
CHEMISTRYSEPTEMBER 30, 2014
SI/SIGNIFICANT FIGURES/SCIENTIFIC NOTATIONS
SCIENCE STARTER
• Verbal Science Starter
OBJECTIVE
• SWBAT – Apply the SI units– Apply the significant rules– Apply the scientific notation rules
AGENDA
–Science Starter–SI units–Significant Figures–Scientific Notation
IMPORTANT DATES
• Makeup Quiz on Wednesday during 4th period or 9th period (Up to 4:15PM)
• Lab – Thursday• Quiz 03 – Friday• Test 01 – Next Friday
Solubility Curve
Solubility
PURE SUBSTANCE
Particle Diagram
PARTICLE DIAGRAMS - ELEMENTS
PARTICLE DIAGRAMS - COMPOUND
PARTICLE DIAGRAMS - HOMOGENEOUS
PARTICLE DIAGRAMS - HETEROGENEOUS
Separation Techniques
SEPARATION TECHNIQUES
• Chromatography• Filtration• Evaporation• Distillation• Magnetism
CHROMATOGRAPHY
• Definition: Method in which components of a mixture is separated based on how quickly different molecules dissolved in a mobile phase solvent move along a solid phase
• One type is called Paper Chromatography– Usually used to identify chemicals (coloring
agents) – Example: Identifying the chemicals in a marker
CHROMATOGRAPHY
FILTRATION
• Method for separating an insoluble solid from a liquid– Popularly used in water treatment– Example: Separating river water
FILTRATION
EVAPORATION
• Method used to separating a homogeneous (solution) mixture of a soluble solid and a solvent
• Involves heating the solution until the solvent evaporates – Examples: Sugar water solution– Heat the solution until the water (solvent) dissolve
leaving behind the sugar
EVAPORATION
DISTILLATION
• Method used to separate a liquid from a solution
• Similar to evaporation but the vapor is collected by condensation
• Example: Sugar Water solution
DISTILLATION
MAGNETISM
• Method used to separate two solids with one having magnetic properties– Example: Separating iron filings and dirt mixture
MAGNETISM
SEPARATING FUNNEL
• Method for separating two immiscible liquids (liquids that do not dissolve well)– Example: Oil and water
SEPARATING FUNNEL
Miscible vs. Immiscible
• Miscible: Forming a homogeneous solution when added together
• Immiscible: do not form a homogeneous solution when added together. Do not dissolve well
SI UNITS
INTERNATIONAL SYSTEM OF UNITS
SI UNITS
• standard system of measurements used in chemistry
• enable scientists to communicate with one another
• there are 7 base units–all other units are derived from these 7
base units
7 SI base units• ampere (A) – measures electric current• kilogram (kg) – measure mass• meter (m) – measure length• second (s) – measure time• kelvin (K) – measure thermodynamic
temperature• mole (mol) – measure amount of substance• candela (cd) – measure luminous intensity
CONVERSION BETWEEN UNITS
• Step 1: Draw the picket fence• Step 2: Identify the given• Step 3: Identify what you are looking for• Step 4: Identify the equivalent relationship• Step 5: Get rid of the units• Step 6: Do the math• Step 7: Check for the final unit(s)
EXAMPLE
• 10 m = __________________cm• Step 1: Draw the picket fence
EXAMPLE – CONT’
• Step 2: Identify the given– 10 m
• Step 3: Identify what you are looking for– cm
• Step 4: Identify the equivalent relationship– 1cm = 0.01 m
EXAMPLE – CONT’
• Step 5: Set up the problem
EXAMPLE – CONT’
• Step 6: Get rid of the units
EXAMPLE – CONT’
• Step 7: Do the math
• Step 8: Check for the final unit(s)
SIGNIFICANT FIGURES
DEFINITION
• a prescribed decimal place that determines the amount of rounding off to be done based on the precision of the measurement• consist of all digits known with
certainty and one uncertain digit.
RULES FOR DETERMINING SIGNIFICANT FIGURES
• nonzero digits are always significant–example: 46.3 m has 3 significant
figures–example: 6.295 g has 4 significant
figures
RULE – CONT’
• Zeros between nonzero digits are significant–example: 40.7 m has 3 significant
figures–example: 87,009 m has 5
significant figures
RULE – CONT’
• Zeroes in front of nonzero digit are not significant–example: 0.009587 m has 4
significant figures–example: 0.0009 g has 1 significant
figure
RULE – CONT’
• Zeroes both at the end of a number and to the right of a decimal point are significant–example: 85.00 g has 4 significant
figures–example: 9.0700 has 5 significant
figures
EXAMPLE
• 1. Give the number of significant figures in each of the following.
• a) 10.0005 g ______
• Do the next 3 problems
EXAMPLES - answers
• b) 0.003423 mm __4____ • c) 67.89 ft ___4___ • d) 78.340 L __5____
MULTIPLICATION/DIVISION RULES
• The number of significant figure for the answer can not have more significant figures than the measurement with the smallest significant figures
EXAMPLES
12.257 x 1.162 = 14.2426234–12.257 = 5 significant figures–1.162 = 4 significant figures–Answer = 14.24 (4 significant figures)
EXAMPLE - Answer
–12.257 = 5 significant figures–1.162 = 4 significant figures
EXAMPLE – Answer cont’
• Answer = 14.24 (4 significant figures)
ADDITION/SUBSTRATION RULES
• The number of significant figure for the answer can not have more significant number to the right of the decimal point
EXAMPLES3.95 + 2.879 + 213.6 = 220.429
EXAMPLE - Answer
–3.95 = has 2 significant figures after the decimal points–2.879 has 3 significant figures
after the decimal points–213.6 has 1 significant figures
after the decimal points
EXAMPLE – ANSWER CONT’
–Answer = 220.4 (1 significant figure)
ROUNDING RULES
–Below 5 – round down–5 or above – round up
EXACT VALUES
• has no uncertainty–example: Count value – number of items
counted. There is no uncertainty–example: conversion value – relationship
is defined. There is no uncertainty• do not consider exact values when
determining significant values in a calculated result
CALCULATOR BEWARE
• CALCULATOR does not account for significant figures!!!!
SCIENTIFIC NOTATIONS
SCIENTIFIC NOTATION
• Use to write very large number and very small number (more manageable)
PARTS
• Before the decimal point = 1 number• After the decimal points = can be
more than 1 numbers (can be optional)• Exponential number = the number of
places the decimal is moved
EXAMPLES
• Change to Scientific Notation– 1,234,400
= 1.234400 x 106
Or
= 1.234400 E6
Do the next 2 problems
EXAMPLES
• 2. 0.1234400 = 1.234400 x 10-1 = 1.234400 E-1
• 3. 0.0000123 = 1.23 x 10-5 = 1.234400 E-5
STANDARD NOTATION
• 2.4 x 105
• = 240,000
• Do the next 3 problems
EXAMPLES - Answer
• 7.8 x 107 = 78,000,000• 9.789 E3 = 9,789• 1.2 x 10-2 = 0.012
CALCULATION RULES - EXPONENTS
• Exponents are count values
CALCULATIONS RULES – ADD/SUBTRACT
• For addition and subtraction, all values must have the same exponents before calculations
CALCULATIONS RULES - MULTIPLICATION
• For multiplication, the first factors of the numbers are multiplied and the exponents of 10 are added
CALCULATION RULES - DIVISION
• For division, the first factors of the numbers are divided and the exponent of 10 in the denominator is subtracted from the exponent of 10 in the numerator
EXAMPLE - ADDITION• Problem: 6.2 x 104 + 7.2 x 103
EXAMPLE – ADD cont’
• Step 1: make sure all values have the same number of exponents• 62 x 103 + 7.2 x 103
EXAMPLE – ADD cont’
• Step 2: Add the factor• 69.2 x 103
• Step 3: put into correct scientific notation• 6.92 x 104
• Step 4: check for significant figures• 6.9 x 104 (Significant rule: can only
have as many as the least significant figure to the right of the decimal)
EXAMPLE - Multiplication
• Problem: (3.1 x 103 )(5.01 x 104)
EXAMPLE – Multiplication (cont’)
• Step 1: multiple the factors and add the exponents• (3.1 x 5.01) x 104+3
• 16 x 107
EXAMPLE – Multiplication (cont’)
• Step 2: Put into correct scientific notation format• 1.6 x 108
EXAMPLE – Multiplication (cont’)
• Step 3: Check for significant figures• 1.6 x 108 (Significant rule: can only
have as many as the least significant figure)
EXAMPLE – Division
• Problem: (7.63 x 103) / (8.6203 x 104)
EXAMPLE – Division (cont’)
• Step 1: Divide the factors and subtract the exponents• (7.63 / 8.6203) x 103-4
• 0.885 x 10-1
EXAMPLE – Division (cont’)
• Step 2: Put into correct scientific notation format• 8.85 x 10-2
EXAMPLE – Division (cont’)
• Step 3: Check for significant figures• 8.85 x 10-2 (Significant rule: can only
have as many as the least significant figure)