Figure Bell work: On your bell work page, please give me a few sentences describing the differences between mixtures and pure substances 2. Turn in Safety Poster, Matter Packet, and the PT scavenger hunt into the box.

1. Solutions may be: a)liquids or gases. b)liquids only. c)solids, liquids, or gases. d)none of the above.

2. Properties that describe the way a substance will react to form other substances are known as: a)homogeneous properties. b)heterogeneous properties. c)chemical properties. d)physical properties.

3. When nitric acid is added to a test tube containing copper, nitrogen dioxide gas is formed. This is the result of: a)an accident. b)an extensive property. c)a chemical reaction. d)a physical change.

1. Solutions may be: solids, liquids, or gases.

2. Properties that describe the way a substance will react to form other substances are known as: chemical properties.

3. When nitric acid is added to a test tube containing copper, nitrogen dioxide gas is formed. This is the result of: a chemical reaction.

Method, Measurement, etc. Modern Chemistry Chapter 2

Scientific Method Scientific Method- logical approach to solving problems by observing and collecting data, formulating hypotheses, testing them, and formulating theories based on data. System- specific portion of matter in a given region of space that has been selected for study (container holding experiment and all of its contents).

Scientific Method 1.Observing and collecting data a)Using senses b)Taking measurements 2.Formulating Hypotheses a)Hypothesis- testable statement based on observations and data b)If, then statements

Scientific Method 3.Testing Hypotheses a)Experiments that include controls (constants) and variables (changes). 4.Theorizing a)Model- an explanation of how phenomena occur and how data or events are related. i.Atomic Model b)Theory- broad generalization that explains a body of facts i.KMT; Collision theory

SI Unit Prefixes - Part I NameSymbolFactor tera-T10 12 giga-G10 9 mega-M10 6 kilo-k10 3 hecto-h10 2 deka-da10 1

SI Unit Prefixes- Part II NameSymbolFactor deci-d10 -1 centi-c10 -2 milli-m10 -3 micro-μ10 -6 nano-n10 -9 pico-p femto-f10 -15

The Seven Base SI Units QuantityUnitSymbol Lengthmeterm Masskilogramkg TemperaturekelvinK Timeseconds Amount of Substance molemol Luminous Intensitycandelacd Electric Currentamperea

Derived SI Units (examples) QuantityunitSymbol Volumecubic meterm3m3 Densitykilograms per cubic meter kg/m 3 Speedmeter per secondm/s Newtonkg m/ s 2 N EnergyJoule (kg m 2 /s 2 )J PressurePascal (kg/(ms 2 )Pa

SI Unit Prefixes for Length NameSymbol gigameterGm10 9 megameterMm10 6 kilometerkm10 3 decimeterdm10 -1 centimetercm10 -2 millimetermm10 -3 micrometerμmμm10 -6 nanometernm10 -9 picometerpm10 -12

Measurement Measurement: a type of observation Qualitative measurements: descriptive words – Ex: hot, cold, heavy, light, big, blue, furry Quantitative measurement: observation made with a measuring instrument and includes both a number and a unit – Ex: ruler, balance, thermometer, graduated cylinder, 13.5°C, 25kg, 17L

Accuracy: How close a measurement is to the true or accepted value – Ex: Weighing a 50g mass 50.00g – accurate 32.18g – not accurate 49.99g – accurate

Precision: How close multiple measurements are to each other – Ex: Take the weight of a 50g massAccurate, precise:50.00g 50.00g49.99g50.00g Not accurate, precise: 32.18g

Example: Evaluate whether the following are precise, accurate or both.

Accurate Not Precise Not Accurate Precise Accurate Precise

An easy way to remember… ACcurate = Correct PRecision = Reproducibility

A student measured the concentration of a solution three times, obtaining values of M, M, and M. The average concentration was thus M. The accepted value was M. The student’s data has: a.good accuracy and good precision. b.poor accuracy but good precision. c.poor accuracy and poor precision. d.good accuracy but poor precision.

A student measured the concentration of a solution three times, obtaining values of M, M, and M. The average concentration was thus M. The accepted value was M. The student’s data has: a.good accuracy and good precision. b.poor accuracy but good precision. c.poor accuracy and poor precision. d.good accuracy but poor precision.

Percent Error 1.Determines Accuracy % Error= Value (measured) – Value (acc.) X 100 Value (acc.) 2.Density of water read at 1.60 g/ml  Accepted Value is 1.00 g/ml  Find the % error

Percent Error 2. % Error= 1.60 – 1.00 X 100 = 60.0% 1.00

Rules for Significant Figures Sig Figs are all of the digits known in measurement and one final which is estimated. All digits 1-9 are significant – Example: 129 – 3 sig figs Zeros between significant digits are always significant – Example: 5007 has 4 sig figs

Rules for Significant Figures Trailing zeros in a number are significant only if the number contains a decimal point – Example: has 4 sig figs, 100 has 1 sig fig Zeros in the beginning of a number whose only function is to place the decimal point are not significant – Example: has 2 sig figs PACIFIC ATLANTIC RULE!

Calculations Using Sig Figs When multiplying and dividing, limit and round to the least number of sig figs in any of the factors. – Example: 23.0cm X 432cm X 19cm = 190,000cm 3

Calculations Using Sig Figs When adding and subtracting, limit and round your answer to the least number of decimal places in any of the numbers that make up your answer – Example: cm cm cm = 255.5cm

How many significant figures are in the measured number ? a.3 b.4 c.5 d.6

How many significant figures are in the measured number ? a.3 b.4 c.5 d.6

6.03 grams grams = ? a.13 grams b.13.1 grams c grams d grams

6.03 grams grams = ? a.13 grams b.13.1 grams c grams d grams

6.03 grams / 7.1 milliliters = ? a.0.8 grams/milliliter b.0.85 grams/milliliter c grams/milliliter d grams/milliliter

6.03 grams / 7.1 milliliters = ? a.0.8 grams/milliliter b.0.85 grams/milliliter c grams/milliliter d grams/milliliter

Scientific Notation Short hand for writing very large or small numbers Two parts: Coefficient and Power of 10 A number between 1 and 10 (can include 1 but not 10). Exponent:  + exponent  - exponent

Scientific Notation Examples: Write the following numbers in scientific notation: 1. 41, ,007, ,000, x x x x x10 8

Calculator time!! Try plugging these into your calculator. Put all answers in scientific notation. *Instead of typing “x 10^,” use the “EE” or “EXP” button!* 37,000 x 7, x (7x10 6 ) x (8x10 5 ) 2.59x x x10 12

LecturePLUS Timberlake40 Dimensional Analysis 1. A person has a height of 2.0 meters. What is that height in inches? Initial unit = mFinal unit = _______ 2) Blood has a density of 0.05 g/mL. If a person lost 0.30 pints of blood at 18°C, how many ounces of blood would that be? Initial = pintsFinal unit = _______

LecturePLUS Timberlake41 How many minutes are in 2.5 hours ? Initial unit 2.5 hr Conversion Final factor unit 2.5 hr x 60 min = 150 min 1 hr cancel Answer (2 SF)

LecturePLUS Timberlake42 Your Turn A rattlesnake is 2.44 m long. How long is the snake in cm? 1) 2440 cm 2)244 cm 3)24.4 cm

LecturePLUS Timberlake43 Solution A rattlesnake is 2.44 m long. How long is the snake in cm? 2.44 m x 100 cm = 244 cm 1 m

LecturePLUS Timberlake44 One more… How many seconds are in 1.4 days? Unit plan: days hr min seconds 1.4 days x 24 hr x ?? 1 day

LecturePLUS Timberlake45 Solution Unit plan: days hr min seconds 2 SF Exact 1.4 day x 24 hr x 60 min x 60 sec 1 day 1 hr 1 min = 1.2 x 10 5 sec

LecturePLUS Timberlake46 Unit Check What is wrong with the following setup? 1.4 day x 1 day x 60 min x 60 sec 24 hr 1 hr 1 min

LecturePLUS Timberlake47 Unit Check 1.4 day x 1 day x 60 min x 60 sec 24 hr 1 hr 1 min Units = day 2 /hr 2 Not the final unit needed

LecturePLUS Timberlake48 Steps to Problem Solving Read problem Identify data Write down a unit plan from the initial unit to the desired unit Select conversion factors Change initial unit to desired unit Cancel units and check Do math on calculator Give an answer using significant figures