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)