Metric System

Essential Questions: What is the metric system? Why is the metric system advantageous over the English system? Metric System: Also known as the SI (International System of Units) Also known as the SI (International System of Units) Based on units that are multiples of 10 Based on units that are multiples of 10 5 basic units most commonly used by chemists: 5 basic units most commonly used by chemists:  Meter  Kilogram  Kelvin  Second  Mole Uses prefixes to change the value of units Uses prefixes to change the value of units

PREFIXSYMBOLVALUE MegaM1,000,000 Kilok1000 Decid0.1 Centic0.01 Millim0.001 Microu Nanon

Lengths Meter is the basic unit of length Other commonly use units of length are cm, mm, and km 1m = 10dm = 100cm = 1,000mm Table C and Table D

UNITRLATIONSHIPEXAMPLE Kilometer (km) 1km = 10 3 m Length of about 5 city blocks Meter (m) Base unit Height of doorknob from the floor Decimeter (dm) 10 1 dm =1 m Diameter of large orange Centimeter (cm) 10 2 cm = 1m Width of a shirt button Millimeter (mm) 10 3 mm=1m Thickness of a dime Micrometer (um) 10 6 um = 1mm Diameter of bacterial cell Nanometer (nm) 10 9 nm = 1mm 10 9 nm = 1mm Thickness of RNA molecule

Volume Space occupied by a sample of matter Base unit is the liter (L ). Other commonly use units of volume are liter, milliliter, cubic centimeter and micro liter

UNITRELATIONSHIPEXAMPLE Liter (L) Base unit Quart of milk Milliliter (ml) 10 3 = 1 Liter 20 drops of water Cubic centimeter (cm 3 ) 1 cm 3 – 1 ml Cube of sugar Micro liter (um) 10 6 n L- 1L Crystal of table salt

Mass  Base unit is kilogram  Common used metric units include liter, milliliter, cubic centimeter and micrometer. Kilogram-mass of 1 L of liquid water at 4C. Weight- force of the pull of gravity on an object.

UNITREALTIONSHIPEXAMPLE Kilogram (km)- base unit 1 kg = 10 3 g Small textbook Gram (g) 1 g = kg Dollar bill Milligram (mg) 10 3 mg =1 g Ten grains of salt Microgram (ug) 10 6 ug = 1 g Particle of baking powder

Temperature Measure of how or cold an object is. Base unit is Kelvin (k). Commonly used units include Celsius and Kelvin KK=C CC = K-273 Table T

Energy The capacity to do work Base unit is the joule (J). Commonly used units include joule and calorie.  1 J =.2390 cal  1 cal = J

Metric Problems Solve the following: 1 Km = ________m 1 cm = ________m 1 mg = ________g 1 ml = ________L 1 m = _________mm 3 1 cm 3 = _________ ml

Write the correct prefix for the following measurements: 1000 g = _________kg m =________mm Which is the larger unit? cm or dm ul or ml

Essential Question: What is scientific notation ? Scientific notation takes the form of M x 10 n. n represents the number of decimal places to be moved. 4 Ex. 84,000 = 8.4 x 10 4 = 8.4 x 10 x10 x 10 x 10 A positive n represents a lager number. Very large and very small numbers are often expresssed in scientific notation.

A negative n number represents a number between zero and 1. Ex = 2.5 x x = _____2.5__________ 2.5 x = _____2.5__________ 10 x 10 x 10 x x 10 x 10 x 10

Scientific Notation Problems: 500 = __________.025 =__________.0008 =__________ 1,000,000 = ________ 1.5 x 10 3 =___________ 1 x10 -1 = ___________ 3.75 x = _________ 4 x 100 = ___________

Multiplication and Division To multiply numbers written in scientific notation, multiply the coefficients and add the exponents. Exs: ( 2.1 x 10 3 )x (4.0 x )= Exs: ( 2.1 x 10 3 )x (4.0 x )= (2.1 x 4.0) (-7) = 8.4 x (2.1 x 4.0) (-7) = 8.4 x x 10 5 = 3.0 x 10 5 = 6.0 x x x = x 10 3 = 5.0 x10 2

Addition and Subtraction To add or subtract the exponent needs to be the same. Exs: 5.4 x x 10 2 = 5.4 x x 10 2 = 5.4 x x 10 3 = 5.4 x x 10 3 = ( ) x 10 3 = 6.2 x 10 3 ( ) x 10 3 = 6.2 x 10 3 (3.42 x ) – (2.5 x ) = (3.42 x ) – (.25 x ) = ( ) x = 3.17 x 10 3

Essential Questions: What is dimensional Analysis? What are conversion factors? How are the two related? Way to analyze and solve problems using the units, or dimensions, of the measurements. Uses conversion factors. Conversion Factor- ratio of equivalent measurements

1 dollar= 4 quarters=10 dimes=20 nickels=100 pennies 1m = 10dm=100cm= 1,000m

Dimensional Analysis Problems How many liters are in 5 L? a. List the known and unknowns: Known: Unknown 5 L ml=? 1 L= 1000ml b. Solve: 5 L x 1,000ml = 5000 ml or 5 x 10 3 ml 1 L

How many seconds are in a workday that lasts exactly eight hours? a. List known and unknowns. Known: Unknown: Time worked =8 h second worked 1h=60 min 1 min=60 s b. Solve : 8 h x 60 min x 60 sec =28,800s or x 1h1 min10 4 s

Water runs through a hose at the rate of 2.5 gal/min/ What is the rate of water flow in gallons/day? 2.5 gal x 60 min x 24 h = 3.6 x 10 3 gal/day 1min 1 h 1 day

Essential questions: What is density? What is the formula for density? Ratio of the mass of an object to its volume. Ratio of the mass of an object to its volume. Density (D =) =mass (m) volume (v) volume (v) Depends on the composition of a substance, not its size Depends on the composition of a substance, not its size Decreases as temperature increases. Decreases as temperature increases.

A cooper penny has a mass of 3.1 g and a volume of 0.35cm3. What is the density of copper (Cu)? D=m D=m v D=.3g D=.3g 0.35cm3 0.35cm3=8.8571g/cm3 =8.9g/cm3 (rounded to 2 sig. figs.)

Significant figures Significant figures- measurement of all the digits that are known, plus a last digit that is estimated

Rules for Determining significant figures 1. All nonzero digits are significant ex: sig. figs ex: 1846 – 4 sig. figs 2. Zero located between nonzero numbers are significant ex: – 5 sig figs ex: – 5 sig figs 3. Trailing zeroes in a number are significant only if the number contains a decimal point ex: sig figs ex: 1000 – 1 sig figs ex: – 4 sig figs

Rules for Determining significant figures cont. 4. Zeroes at the beginning of a number whose only function is to place the decimal are NOT significant ex:.0082 – 2 sig figs ex: – 3 sig figs ex: – 3 sig figs

Subtraction and addition with sig figs..When adding or subtracting-limit and round your answer to least decimal places in any number that makes up your answer. Exs L L L L L Final answer : L

More Examples of addition and subtraction with sig figs Exs m 4.01 m 4.01 m +6.8 m +6.8 m m m Final answer 99.3 m 8.63 L -7.0 L -7.0 L 1.63 L Final answer 1.6 L

Multiplication and division with sig figs. ► When multiplying and dividing, limit and round to the least number of sig figs. ► Ex: 7.55 m X.34 m = m 2 = 2.6 m 2 (2 sig figs)

Essential Questions: What is percent error? How do you calculate percent error? Accepted Value-correct value based on reliable references Measured Value (experimental value)-the value measured in the lab. Error=experimental value-accepted value Percent error = measured value - accepted value x 100 accepted value accepted value

What is the percent error for a student who actual weight is 107 lbs, but when she steps on the scale is weights 114 lbs? Let’s assume the scale is incorrect and that she is not eating too many Big Macs! =114lbs-107 lbs 107lbs =7% Table T