Chemical Changes are characterized by the following:
Definition of a substance.
Basic characteristics of pure substance:
The two categories of pure chemical substances.
Basic identification of a mixture.
Brainstorm more examples of heterogenous mixtures.
Definition of Conservation of matter.
Ch1.12.matter measurement ppt
Chapter 1 Learning Objectives•Distinguish Science from Technology•Define Alchemy and Natural Philosophy•Briefly describe the contributions of Bacon, Galileo, and Carson to the perceptionsof science.•Define Hypothesis, Scientific Law, Scientific Theory, and Scientific Model, andexplain their relationships in science.•Define Risk and Benefit, and give an example of each.•Estimate a Desirability Quotient from benefit and risk data.•Give an example of a use of Chemistry in your daily life and in society at large.•Distinguish Basic Research from Applied Research.•Differentiate: Mass & Weight; Physical & Chemical Change; Physical & ChemicalProperties.•Classify matter according to state and as mixture, substance, compound, and/orelement.•Assign proper units of measurements to observations and manipulate units inconversions.•Calculate the density, mass or volume of an object given the two other quantities.•Distinguish between heat and temperature.•Explain how the temperature scales are related.•Use critical thinking to evaluate claims and statements.
Matter• Science & Technology• Matter• Physical and Chemical Changes• Pure Substances• Mixtures
A Science for All SeasonsChemistry is the study of matter and its changes.Everything we do involves chemistry.
Science & Technology July 8, 2011 Space Shuttle Atlantis lifts off from Launch Pad 39B at Kennedy Space Center, FL. Squid in Space are on Board!! Photo Credit NASA See the launch: http://www.youtube.com/watch?v=tqrDWa7Eabk
What is Matter?• Everything that has mass and volume is called matter. Water is present in three phases…name ‘em!
Green and Sustainable ChemistryGreen chemistry uses materials and processes thatare intended to prevent or reduce pollution at itssource.Sustainable chemistry is designed to meet the needsof the present generation without compromising theneeds of future generations.
ScienceScience has five characteristics. Science is• Testable• Reproducible• Explanatory• Predictive• Tentative
ScienceScientific models are tangible items or pictures usedto represent invisible processes. Elena OBrien, scientific support rep for antibody maker Abcam, shows the new look for leather still sexy, now office-appropriate . Who are these guys? What are they looking at? So which one is a scientific model? ..really?
Molecular ModelingMolecules are groups of two or more atoms heldtogether by chemical bonds.Molecular models are three-dimensionalrepresentations of molecules.Check this out:http://jmol.sourceforge.net/
Changes in Latitude… Changes in Matter…• All matter, regardless of state, undergoes physical and chemical changes.• These changes can be microscopic or macroscopic.
What is a Physical Change?• A physical change occurs when the substance changes state but does not change its chemical composition.• The form or appearance has changed, but the properties of that substance are the same (i.e. it has the same melting point, boiling point, chemical composition, etc.)
Physical Change: Examples• Dry Ice is Sublime…. http://www.youtube.com/watch? v=W3PkuaYYOtg&feature=related• Others: cutting a piece of wood into smaller pieces, etc. Watch this…http://www.youtube.com/watch?v=fy81xU6vBC8
Chemical Changes:• A chemical change occurs when a substance changes into something new. This occurs due to heating, chemical reaction, etc.• You can tell a chemical change has occurred if the density, melting point or freezing point of the original substance changes.• Many common signs of a chemical change can be seen (bubbles forming, mass changed, etc).• I love Bill Nye…• http://www.youtube.com/watch?v=5BF4We7qMf0&feature=related
• Reaction with acids • Ability to act as• Reaction with bases reducing agent (alkalis) • Reaction with other• Reaction with oxygen elements (combustion) • Decomposition into• Ability to act as simpler substances oxidizing agent • Corrosion
Chemical Changes: Examples• Methane Hydrate….zoiks!http://www.netl.doe.gov/ technologies/oil- gas/futuresupply/meth anehydrates/mainconte nt.htm
• Physical and chemical properties may be intensive or extensive.• Better check this out… http://www.youtube.com/watch? v=m0IH3Hgy3oI&feature=related
• Intensive properties such as density, color, and boiling point do not depend on the amount of the sample of matter and can be used to identify substances.
• Extensive properties such as mass and volume do depend on the quantity of the sample.
• Physical properties are those that we can determine without changing the identity of the substance we are studying.
• The physical properties of sodium metal can be observed or measured. It is a soft, lustrous, silver-colored metal with a relatively low melting point and low density.• Hardness, color, melting point and density are all physical properties.
• Chemical properties describe the way a substance can change or react to form other substances. These properties, then, must be determined using a process that changes the identity of the substance of interest.
• One of the chemical properties of alkali metals such as sodium and potassium is that they react with water. To determine this, we would have to combine an alkali metal with water and observe what happens.• This is nutz: http://www.youtube.com/watch? v=m55kgyApYrY• In other words, we have to define chemical properties of a substance by the chemical changes it undergoes.
Matter is identified as either a….• Pure Substance: Element orCompound,or a….• Mixture: Homogeneous Mixtureor Heterogeneous Mixture
• Can a pure substance be furtherbroken down or purified by physicalmeans? (Give examples)• Does each pure substance have itsown characteristic properties that aredifferent from the set of properties ofany other pure substance? (Giveexamples)
• Do PS have constant composition?• Can PS be changed in identity and properties by chemical methods?• Do PS have constant properties?
Mixtures are two or more pure substances thatare NOT chemically combined.•Do mixtures have constant boiling points?•Do mixtures have constant melting points?
Compounds Elements• Can be decomposed • Cannot be into simpler decomposed into substances by simpler substances by chemical changes, chemical changes always in a definite • Atoms? ratio• Molecules?
• Variable composition• Components retain their characteristic properties• May be separated into pure substances by physical methods• Mixtures of different compositions may have widely different properties
Homogenous mixtures look the samethroughout but can be separated byphysical means (dissolution, centrifuge,gravimetric filtering, etc.). Examples:milk, yogurt
• Solutions are homogenous mixturesthat do not scatter light.• These homogeneous mixtures arecreated when something is completelydissolved in pure water.•They are easily separated bydistillation or evaporation.Examples: sugar water, salt water
• Heterogeneous mixtures are composed oflarge pieces that are easily separated byphysical means (ie. density, polarity,metallic properties).• Examples?
• Do not have same composition throughout• Components are distinguishableExamples: fruit salad, vegetable soup, etc.
(And how the Kinetic Molecular Theory affects each) •Solids •Liquids •Gases •Plasma
•Have a definite shape •Have a definite volume Kinetic Molecular TheoryMolecules are held close togetherand there is very little movementbetween them.
•Have an indefinite shape •Have a definite volumeKinetic Molecular Theory:Atoms and molecules have morespace between them than a soliddoes, but less than a gas (ie. It ismore “fluid”.)
•Have an indefinite shape •Have an indefinite volumeKinetic Molecular Theory:Molecules are moving in randompatterns with varying amounts ofdistance between the particles.
At 100°C, water Below 0°C, water becomes water solidifies to become vapor, a gas. ice. In the solid state, Molecules can water molecules are move randomly held together in a over large rigid structure. distances.Between 0°C and 100°C, water is a liquid.In the liquid state,water molecules areclose together, butcan move aboutfreely.
Changing states requires energy in eitherthe form of heat. Changing states may alsobe due to the change in pressure in asystem.Heat of vaporization, Hv Heat of formation, Hf.
• Plasma is by far the most common form of matter.• Plasma in the stars and in the tenuous space betweenthem makes up over 99% of the visible universe andperhaps most of that which is not visible.• Plasma is a high energy electrically charged mixtureof ions and electrons. While plasma is the mostabundant phase of matter in the universe, on earth itonly occurs in a few limited places. Plasma appearson earth only in places like lightning bolts, flames,auroras, and fluorescent lights.
On earth we live upon an island of "ordinary" matter. Thedifferent states of matter generally found on earth aresolid, liquid, and gas. We have learned to work, play, andrest using these familiar states of matter. Sir WilliamCrookes, an English physicist, identified a fourth state ofmatter, now called plasma, in 1879. Plasma temperaturesand densities range from relatively cool and tenuous (likeaurora) to very hot and dense (like the central core of astar). Ordinary solids, liquids, and gases are bothelectrically neutral and too cool or dense to be in aplasma state.The word "PLASMA" was first applied to ionized gas byDr. Irving Langmuir, an American chemist and physicist,in 1929.
Star formation in the Eagle NebulaSpace Telescope Science Institute, NASA(below) (Above) X-ray view of Sun from Yohkoh, ISAS and NASA
Plasma radiation within the PrincetonTokamak during operation.
Laser plasma interaction during inertialconfinement fusion test at theUniversity of Rochester.
Both inertial and magnetic confinement fusion researchhave focused on confinement and heating processes withdramatic results. The next stage of operating powerreactors will produce about 1 GW of power and operateat 120 million degrees Kelvin.
Plasma consists of a collection of free-moving electrons and ions - atoms thathave lost electrons. Energy is needed tostrip electrons from atoms to make plasma.The energy can be of various origins:thermal, electrical, or light (ultravioletlight or intense visible light from a laser).With insufficient sustaining power,plasmas recombine into neutral gas.
Plasma can be accelerated and steered byelectric and magnetic fields which allowsit to be controlled and applied. Plasmaresearch is yielding a greaterunderstanding of the universe. It alsoprovides many practical uses: newmanufacturing techniques, consumerproducts, and the prospect of abundantenergy.
EXAMPLES: •Printing on plastic food•Computer chips and containersintegrated circuits •Energy-efficient window•Computer hard drives coatings•Electronics •High-efficiency window•Machine tools coatings•Medical implants and •Safe drinking waterprosthetics •Voice and data•Audio and video tapes communications components•Aircraft and automobile •Anti-scratch and anti-glareengine parts coatings on eyeglasses and other optics
Plasma technologiesare important in •Waste processingindustries with annualworld markets •Coatings and filmsapproaching $200 •Electronicsbillion •Computer chips and integrated circuits •Advanced materials (e.g., ceramics) •High-efficiency lighting
WaterPurification Plasma-based sources Systems can emit intense beams of UV & X ray radiation or electron beams for a variety of environmental applications.
For water sterilization, intense UV emissiondisables the DNA of microorganisms in thewater which then cannot replicate. There isno effect on taste or smell of the water andthe technique only takes about 12 seconds.
This plasma-based UV method is effectiveagainst all water-born bacteria and viruses.Intense UV water purification systems areespecially relevant to the needs ofdeveloping countries because they can bemade simple to use and have lowmaintenance, high throughput and lowcost. Plasma-based UV water treatmentsystems use about 20,000 times less energythan boiling water!
•There is no observable change in thequantity of matter during a chemicalreaction or a physical change.•In other words, matter cannot becreated nor destroyed. It is justconverted from one form to another
DensityDensity is defined as theamount of matter in a givenamount of space.d = m/VThe density of copper is8.94 g/cm3.
Density: Practice ProblemCalculate the density of a metal sample with a massof 18.96 g and a volume of 4.31 cm3. d = m/V = 18.96 g/4.31cm3 = 4.40 g/cm3
Numbers in Chemistry: Accuracy & Precision • Why Measure? CO2? Heat? O3? Radiation? Fossil Fuels? Hydrogen Economy? • Exact Numbers vs. Measurements…What’s the difference?
A Visit from Ironman…or is that “Fe”-man? • Ironman knows how to measure things with great accuracy • In Class Activity: L, W, T of your Chemistry text! Volume? • Were you precise? • Accurate? • Both? • How do you know? • What is a “true value”, AKA “accepted value”?
A Game of Chance? Skill?• What’s best? Accuracy or Precision?• How can this objective be achieved in science?• Does this connect to the lab? How?
Are You Sure You Are Uncertain? • What’s the difference between these two pictures? • Whys does it matter to me? • Which measuring instrument is better? • What makes it better? • Hmmm…uncertainty?
Instrument Uncertainty • OK ± What? Why? • Certainty vs. an estimated digit on a measuring instrument • Obtain a measuring instrument from lab & explain to partnerMr. Tyler & Mr. Bean give extra help to aChemistry student. (Which one is “Beaker”?) what the estimated digit in a measurement has to do with uncertainty. Test Your Knowledge!! 1) What is the instrument uncertainty for the 100 mL graduated cylinders we use in lab? 2) What is the instrument uncertainty for the 100 mL beakers we use in the lab?
Significant Figures Rule!!! There are three rules on determining how many significant figures are in a number: 1. Non-zero digits are always significant. 2. Any zeros between two significant digits are significant. 3. A final zero or trailing zeros in the decimal portion ONLY are significant. • Focus on these rules and learn them well. They will be used extensively throughout the remainder of this course. You would be well advised to do as many problems as needed to nail the concept of significant figures down tight and then do some more, just to be sure. • Please remember that, in science, all numbers are based upon measurements (except for a very few that are defined). Since all measurements are uncertain, we must only use those numbers that are meaningful. A common ruler cannot measure something to be 22.4072643 cm long. Not all of the digits have meaning (significance) and, therefore, should not be written down. In science, only the numbers that have significance (derived from measurement) are written.
Significant Figures…The Rules in More Detail Significant figures a) All non-zero digits are significant e.g. 1.234 has 4 significant figures. The information conveyed by the digits is that there is one unit, 2 numbers of 0.1mm, 3 numbers of 0.01 mm and 4 numbers of 0.001 mm. Therefore each digit conveys specific information regarding that place value. b) Zeroes between non-zero digits are significant e.g. 12.004 has 5 significant figures The two zeroes in the value convey the information that there are zero numbers of 0.1mm and zero numbers of 0.01 mm. Note that there is significant information about smaller units and larger ones. c) At the end of a number all zeroes are significant, even after the decimal point e.g. 9.100 has 4 significant figures The two zeroes are specifically conveying the information that there are zero numbers of 0.01 mm and zero numbers of 0.001 mm. d) At the end of a number all zeroes are usually significant if before the decimal point. e.g. 4000 has four significant figures, This implies that the digit filling the units place is not definitely known e) Zeroes which merely assign place value to a non zero digit are not significant. e.g. If 4000 is correct to the nearest ten, it has only three significant figures. This implies that the digit filling the units place is not definitely known and if 4000 is correct to the nearest hundred it has 2 significant figures. This implies that the digit filling the units place and the tens place are not definitely known. e.g. when the population of a country is said to be 900,000,000 the figure is probably correct to the nearest 100 million. Thus there are 9 units of size 10 8 units. That is to say, this number has just one significant figure, even though there are nine digits reported. f) Zeroes reported at the beginning of a number before or after the decimal point are always non- significant. These are also placeholder zeroes. 007 metre = 7 x 10o m ............................1 sig. fig. 0.007 metre = 7 x 10-3 m ...........................1 sig. fig. 0.070 metre = 7.0 x 10-2 m.........................2 sig. fig.
Significant Figures & Measurement• Sig Fig’s are BASED on measurements.• The number of Sig Fig’s you report in a measurement depends on the ACCURACY of the measuring device.
Hmm…What’s a Derived Unit?? • Density • How do you calculate density? • Do you need to make measurements? How many? • How could you calculate the density of air at sea level? • What is a hematocrit?
Energy: Heat and TemperatureEnergy is the ability to do work or transfer heat.Energy exists in two major forms: • Potential energy is stored energy. • Kinetic energy is energy in motion.
Heat vs. TemperatureWhat is the difference between Heat &Temperature?Heat is energy that is transferred from hotter objectsto cooler objects.Temperature is the average kinetic energy of theatoms or molecules that make up an object.
Units of HeatHeat energy is often measured in calories or joules.• One calorie (cal) is the amount of heat required to change the temperature of 1.00 g of water 1.00 oC.• A calorie is 4.184 joules (J). 1 cal = 4.184 J
Food CaloriesA food calorie (Cal, “C” is capitalized) is actually akilocalorie. 1 Cal = 1 kcal = 1000 cal = 4184 J
Energy • What is energy? • What units quantify energy? (cal, Cal, Joule?)James Prescott Joule • What is a calorie? A Calorie? …a joule? • Law of Conservation of Energy? • SH H2O = 4.184joules/g•oCHmm..what’s more energy? Cal or cal?
Physical Properties of Water• USGS Site: http://ga.water.usgs.gov/edu/waterproperties.html1) Explain why water is considered an excellent thermal buffer and why this is ecologically significant.2) Water has it’s maximum density at 4oC, not 0oC. Explain why this occurs and how it is ecologically significant.
Unit Analysis, Factor-Label Method, Dimensional Analysis, Bridge Building…..all synonyms!• "I thought I knew everything and that speech was the only thing that mattered in high school. When Mr. Bean taught our Chemistry class unit analysis, I didnt care about it at all. I was making plans for the weekend with my girlfriend who loved me because I was a speech team stud with offers from Brown, Princeton and Harvard and not because of Chemistry. While my homies were home solving unit analysis problems, I was practicing a speech. Then one day I was hit hard at a speech tournament. Splat…no mo swag. I totally clutched on my speech, no points, zippo. I was despondent. My girl friend dumped me. My parents, who used to brag about my speech stats, started getting on my case about my grades. I decided to throw myself into my school work. But I couldnt understand anything. I would get wrong answers all of the time. I now realize that my failure in school came from never having learned unit analysis. I finally decided to learn unit analysis. After three hours of studying unit analysis I get it. My swag is back. My speechie homies are chillin’. Last weekend I placed first in the speech tournament. My girlfriend came back to me and my parents are off my case.” Jeff
Whats the Method? Unit AnalysisExample 1: This is a structured way of helping you to convert units. With this method, you can easily and automatically convert very complex units if you have the conversion formulas. The method involves the following stepsExample: Convert 6.0 cm to km1. Write the term to be converted, (both number and unit) 6.0 cm2. Write the conversion formulas 100 cm = .00100 km3. Make a fraction of the conversion formula, such that….. a) if the unit in step 1 is in the numerator, that same unit in step 3 must be in the denominator. b) if the unit in step 1 is in the denominator, that same unit in step 3 must be in the numerator. Since the numerator and denominator are equal, the fraction must equal 6.0 cm .00100 km 100 cm4. Multiply the term in step 1 by the fraction in step 3.5. Perform the indicated calculation rounding the answer to the correct number of significant figures. 0.000060 km or 6.0 E -5 km
..and finally…everybody and mean everbody talks…about sigfigs!• http://www.youtube.com/watch? v=X5G9tIe84lE&feature=related• ..and from my generation…a little Dixie Chicken:• http://www.youtube.com/watch?v=3z- GwdaKrn8&feature=related