Presentation on theme: "What is Chemistry? The study of the composition, structure, & properties of substances and changes it undergo. A chemical is any substance that has a."— Presentation transcript:
What is Chemistry? The study of the composition, structure, & properties of substances and changes it undergo. A chemical is any substance that has a part in a chemical rxn or is produced. Practical Uses Clothing – synthetic fabric Nonstick cookware - Teflon Pharmaceuticals - medications
Categories of Science i. Biological – ii. Physical - Concerned with non living things Concerned with living things
Branches of Chemistry Organic – Study of living - contains carbon. Inorganic – study of non-living – no carbon. Physical – study of properties, transformations, and interrelationship of energy and matter.
Branches of Chemistry Analytical – identification of substances & study of composition of materials Biochemistry – Process that occurs in living things connects biological processes w/ chemical processes. Theoretical – the use of math & computers to understand the principles behind observed chemical behavior and to design and predict the properties of new compounds.
Matter & Its Properties Atom – the smallest particle of an element that retains the properties of that element. Elements – A substance that cannot be changed into a simpler substance under normal lab conditions
Physical Properties Properties – characteristics enabling us to distinguish differences in matter. Physical properties – can be observed or measured w/o changing the identity of material Extensive physical properties – depends on the amount of matter. (mass, length, volume). Intensive physical properties – does not depend on mass, melting pt, boiling pt, density, color, ductile, malleable, crystal shape, etc.
Physical Change A physical change is the changing of a substance does not alter the chemical composition. It can change states. Cutting, grinding, expanding
States of Matter Solid Liquid Gas Plasma Definite shape & volume Definite volume, not shape Neither definite shape or volume Gaseous system with ions
Chemical Properties/Changes Alters chemical identification. Chemical reaction-Reactants -> Products Reactants are the substances you start off with And they then react and yields a new product. Ex. Wood burning, matches, letting milk stand so it can turn sour, iron rust, tarnishing silver. Na + Cl NaCl Charcoal + O 2 CO 2 Fe + O 2 Fe 2 O 3
Physical or Chemical ? Physical Chemical Physical
Classification of Matter Mixtures – retain own composition & properties. Heterogeneous – Not uniform Homogeneous – Uniform Elements – is on the periodic chart. (Simplest form) compounds – chemically combined ex. NaCl Pure substance – has a fixed composition. Are either compd. or elements. 1.Every sample has exactly the same characteristic prop. 2.Every sample has exactly the same composition. ex. H 2 O 11.2 % H, 88.8 % O
Distillation Method for physically separating a mixture of liquids or a solid dissolved in a liquid
Matter & Energy a. Matter – Occupies space and has mass. Inertia – Resistance to change in motion. Weight Vs. Mass - Weight is the measure of gravitational pull. Mass is quantity of matter. Law of conservation of mass: Mass is neither created nor destroyed.
Energy – Ability to do work or cause change Types of Energy - Kinetic Energy – in the form of motion Potential Energy – Stored energy depends on composition or position Law of Conservation of Energy Energy can change form, but it cannot be Created nor destroyed under ordinary cond.
Energy and changes in matter Exothermic – produce heat. Energy is released in the form of heat. H + O H 2 O + Heat Endothermic – gain heat. Energy, in a form of heat, is absorbed. Ex. Melting ice
Periodic Table Families or Groups – Vertical columns, # 1 – 18. Elements share properties. Periods – horizontal rows Metals – Good conductors of heat & electricity. Shiny, luster, malleable, ductile, tensil. Non-Metals – Poor conductors of heat/electricity. Metalliods – Share characteristics of metals & nonmetals. Semiconductors Noble Gases – unreactive gases.
Symbols for elements IUPAC – International Union of Pure & Applied Chemistry O – oxygenH – N - Na - Sb stibium – antimony Cu cuprum – copper Au Aurum – gold Ag Argentum – silver Na Natrium – sodium
Scientific method- logical approach to solutions of problems Parts – Observations – collecting data Quantitative & Qualitative Generalizing – Organize, analyze, & classify Hypothesis – testable statement Law – Describes a variety of scientific behavior Theory – Explains why things occur. Broad generalization that explains a body of facts or phenomena. Model Testing - experimenting
Types of Data Qualitative – descriptive nonnumeric results Quantitative – gives definite, usually numeric, results Number Unit
Graphing Title graph Label axis – numbers & units Choose Scale Independent variable – X – axis (Usually Time) Dependent variable – Y – axis Plot Points Draw Best Fit Line Line graph Bar graph Pie/ circle graph Types of Graphs: Directly proportional Inversely proportional Dividing 1 by the otherIf product is constant gives a constant value
Pie Graph Data Gender# of ppl Elderly27 Women13 Men6 Children15 Total61 To get percentages: Get part / whole # X 100 Elderly: 27/61 X 100 = 44.3 % Women Men Children Total 21.3 % 9.8 % 24.6 % 100 % Degrees: 44.3 = X °
Standards of Measurement SI – International System of Units 1960 Units of Measurement-SI system 1. Based on units of ten, makes it easier to use 2. Used world wide SI Base Units - (pg 34) Fundamental SI Units Qty Symbol Unit name Unit abbreviation Length l Meter m Mass m Kilogram kg Volume V Liter L Time t second s Temperature T kelvin K Amount of substance n mole mol
SI Units Kilohecto deka base deci centimilli King Henry Died by Drinking Chocolate Milk There are 1000 base units in one kilo There are 1000 milli in one base unit
Derived SI Units Density = Mass/volume Volume = l X w X h Find the density of a piece of aluminum w/ a volume of 4.0 cm 3 and a mass of 10.8 g. D = m/v D = 10.8 g 4.0 cm 3 D = 2.7 g/cm 3
Derived Units Density What is the density of a block of marble with a mass of g and a Volume of ml? D = m v D = 3.685g/ml D = g ml
Accuracy Vs. Precision ACCURACY – Refers to the agreement of a particular value with the true value. PRECISION – Refers to the degree of agreement among several elements of the same quantity.
Precise & Accurate Precise Neither
Percent Error What is the percent error for a mass measurement of 17.7 g, given that the correct value is 21.2 g? Accepted value - Experimental value Percent error = accepted value. % error = 21.2 g g 21.2 g X 100 X 100 = 16.5 % error
Significant Figures All digits known plus one final digit Measurements from equipment
Counting Significant Figures All non-zero numbers are significant Zeros * Leading zeros – never * Captive zeros – Always * Trailing zeros * With a decimal – count * Without a decimal – dont count
3 Questions for Zeros 1. Is there a number in front? No – Not significant Yes – May be… go to #2 & #3 2. Is it trapped? No – Not significant Yes - It is significant 3. Is there a Decimal? No – Not Significant Yes – It is significant
Counting Significant Figures g cm m L kg km
Calculations – multiplication & Division * The answer is rounded off to the same number of significant figures as in the measurement with the fewest sig. Fig. * 6.43 ml X ml = ml * 2.50 g / 0.04 cm 3 = g/cm 3
Calculations – Addition & Subtraction Results should be rounded off so that the final digit is in the same place as the number with the fewest digits ____ \. \ – = Rounding Less than 5 = stay the same More than 5 = increase one If 5 = if odd increase by one if even leave it alone
Scientific Notation * g (2 significant figures) 2.4 X g | * m (3 significant figures) | 5.02 X 10 4 m * cm ( 2 significant figures) 4.6 X 10 –4 cm | Must be a number from 1 to 9 !!!!!!!!!
SI - Prefixes 1.0 Kg = g 1.0 hg = 100 g 1.0 d a g = 10 g Grams, liters, meters 10 dg = 1.0 g 100 cg = 1.0 g mg = 1.0 g Kilo, hecto, deka, Base, deci, centi, milli Grams, liters, meters King Henry Dances barbarically down center maine King Henry Died by drinking chocolate milk
Chemistry Dominoes Rules 1. Dont slam or throw dominoes 2. Take turns 3. Quickly get quiet when I call for your attention. To End The Game 1. The player who makes the connection to the last domino wins 2. Count up the number of dominoes left on the table. Each domino is 1 point. 3. Award the winner the points left on the table.
Game Play 1. Each payer draws 1 domino to see who plays first (high domino) 2. Shuffle (wash) the dominoes 3. Each player draws 5 dominoes 4. Player 1 plays a number blank (if no number blank, draw) This is the starting domino 5. Player 2 plays a number blank. (if no number blank, draw) This is the end domino. 6. For the rest of the game, players play dominoes that will cancel the top number on the domino 7. If you can not play, draw 1 domino. This domino may be played.
Factor Label Draw your T Write conversion-equivalent statements to… Cancel out units Top – Multiply, Bottom – Divide 1. The mass of a quarter is 10.4g, how many milligrams is that? ________|__________ 10.4g | g mg = mg
Factor Label Express a distance of 28. Meters in centimeters and then in kilometers. 28. m m cm = 2,800 cm 28. m m km = km
Factor Label * 1.0 year = __________________ seconds 1.0 yr 1 yr 365 days 1 day 24 hrs 1 hr 60 min 1 min 60 sec = 31,536,000 sec 3.2 X 10 7 sec
Factor Label Dimensional Analysis 1. How many kilograms are in grams? 2. How many liters are in 13.4 kL? 3. A pencil is 7.5 centimeters, how many millimeters ? 4. You want to order a bicycle with a 225 mm frame, but the sizes in the catalog are given only in inches, what should you order? 5. A student enters a 10.0 km run. How many yards is the run?
Quiz 25.3 ft = _______________ mm 7.5 mg = ______________ hg 12.5 kl = _______________ ml 5.4 X 10 –6 km= _________ mm 3.0 L = ________________ cm weeks = ____________ sec
Heat & Temperature Temperature – measure of average kinetic energy Heat – sum of kinetic energy in all of the particles in a sample A tub of boiling water & a cup full of boiling water
Units of Temperature Celsius Kelvin Fahrenheit
Heat Transfer Convection Convection – transfer of heat by the motion of particles in a fluid Conduction Conduction – transfer of heat through matter by colliding particles Radiation Radiation – transfer of energy in the form of electromagnetic waves Heat always moves from high energy to low energy. (hot to cold)
Examples Hot air balloons Hot water and cold water mixing Heating a pan Boiling water
Units of Heat Joule Calorie The SI unit of heat energy as well as all Other forms of energy. Calorimeter – measures the energy absorbed or released as heat in a chemical or physical change. 1.0 cal = joules
Heat Capacity Amount of heat energy needed to raise the temperature of a sample 1 o C
Specific Heat Amount of heat energy needed to raise the temperature of 1g of a sample 1 o C. Equation Q = m X C p X T Q = energy lost/ gained M = mass C p = specific heat T = delta T = change in temp. UNITS Joules = J Grams = g J/g* o C o C
Problems. A 4.0 g sample of glass was heated from 1 o C to 41 o C and was found to have absorbed 32 J of heat. What is the specific heat of this type of glass?
Problems. A 4.0 g sample of glass was heated from 1 o C to 41 o C and was found to have absorbed 32 J of heat. What is the specific heat of this type of glass? Q = m C p T m=4.0g T=41 o C-1 o C=40 o C Q=32J C p = 0.20J/g o C
problem How much heat did the same glass sample gain when it was heated from 41 o C to 71 o C?
problem How much heat did the same glass sample gain when it was heated from 41 o C to 71 o C? Q = m C p T m=4.0g T=71 o C-41 o C=30 o C C p =0.20J/g o C Q=(4.0g)(0.20J/g o C)(30 o C) Q=24J
Quiz m = __________ km ml = ________ L kg = __________cg ml = __________cm 3 5.D = 2.45 g/ml, mass = 12.5 g vol. = ? 6.Vol = 25.5 ml, mass = 32.3 g D = ? 7.D = 3.4 g/cm 3 vol = 1.5 cm 3 mass = ? 8.List the things that a graph must contain (at least 4 things)