Intro+to+Chemistry+and+Chemistry+Measurement

 //**Introduction to Chemistry**//  //**and Chemistry Measurement **// **editor: Ally Luongo ** **Period A ** In these chapters we learn all about the basic concepts of chemistry. We explore the definition of chemistry and all the different types of chemistry. Also, the importance of studying chemistry is explained. We learn how chemistry affects all different aspects of life, and how chemistry is useful. In addition, we learn how to measure, chemistry style! We learn chemistry measurements, SI, and different chemistry units.



//**CH﻿APTER 1**// ** 1.1 Chemistry ** Coeditor: Ian Kelly Member: Billy Arruda **What is Chemistry?**
 * __Matter__ - anything that had mass and occupies space
 * __Chemistry__ - the study of the composition of matter and the changes matter undegoes
 * Because living and nonliving things are made of matter, chemistry affects all aspects of life and most natural events

**Areas of Study** Chemists often work in more than one of these areas, as understandings in some of these areas can lead to advances in others. **Pure and Applied Chemistry** Nylon Aspirin Technology **Why Study Chemistry?**
 * Chemistry is an extremely vast field, and so chemists tend to focus on one area.
 * There are five traditional areas in study of chemistry, including organic organic chemistry, inorganic chemistry, biochemistry, analytical chemistry, and physical chemistry.
 * __Organic Chemistry__ is defined as the study of all chemicals containing carbon (including living things on Earth).I
 * __Inorganic Chemistry__ is the study of chemicals that, in general, do not contain carbon.
 * __Biochemistry__ is the study of processes that take place in organisms.
 * __Analytical Chemistry__ is the area of study that focuses on the composition of matter. ex. measuring lead levels in water
 * __Physical Chemistry__ is the area that deals with the mechanism, rate, and the energy transfer that occurs when matter undergoes a change. ex. when water evaporates.
 * __pure chemistry- the pursuit of chemical knowledge for its own sake__
 * __applied chemistry- research that is directed toward a practical goal or application__
 * pure research can lead directly to an application, but an application can exist before research is done to explain how it work
 * Wallace Carothers experimented testing Staudinger's proposal of small units linked together in cotton and silk
 * the experiments showed Staudingers proposal correct
 * during the experiment Carothers discovered nylon ( not naturally produced by nature )
 * researches suspected that aspirin could keep blood clots from forming
 * in 1971 it was discovered that aspirin can block the production of a group of chemicals that causes pain
 * these same chemicals are also involved in the formation of blood clots
 * __Technology- the means by which a society proveds its members with those things needed and desired__
 * allows us to do things more quickly with less effort
 * allows us to do things that would be impossible without technology, ex: flying to the moon
 * in any technology, scientific knowledge is used in ways that can benefit or harm people and the enviornment
 * the debates on scientific knowledge are usually debates about the risks and benefits of technology
 * Chemistry is useful in explaining the natural world, preparing people for career opportunities, and producing informed citizens.
 * It can help to solve problems such as waste removal, removing sunblock and stains from a shirt, and helping to improve in a profession.
 * It can help to explain our natural world.
 * It explains reasons why things happen, such as food rotting, water expanding when it freezes, and why yeast makes bread bough rise.
 * It is a key to understanding our world.



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 * It can help us to prepare for a career.
 * Chemists can make huge contributions to society in their discoveries and in their work.
 * Many careers, such as firefighters, turf managers, and photographers can benefit from an understanding of chemistry.
 * Firefighters need to know what chemicals to use to fight different fires.
 * Turf managers need to understand how to keep the grass growing strong and healthy.
 * Photographers need to be able to perform a chemical process to develop photos.
 * It can help us be informed citizens.
 * Industry, private funds, and even the government provide funds for scientific research.
 * As a result, areas of research compete for funding, such as space exploration and cancer research.
 * Critics make a case that either side (they support) should receive more funding.
 * A great example is that some scientists believe NASA should recieve less funding than cancer research, as it is an immediate need.
 * Others point out that this space research has led to new technologies such as heart monitors and smoke detectors.
 * Citizens must be well informed to decide what they thinks deserves more funding.

** 1.2 Chemistry Far and Wide ** Coeditor: Grant Casey Member: Catherine Murray **Agriculture** Productivity 1. Test soil to see if it contains the right chemicals to grow a particular crop and recommend ways to improve the soil 2. Use biotechnology to develop plants that are more likely to survive in a drought or insect attack 3. Finding reliable ways to determine when a crop needs water Crop Protection -An example is pin worms, where there is a chemical that attracts male pin worm moths wrapped around a tomato stem. When the chemical is released, it interferes with the mating process so that fewer pin worms are produced. **The Environment** Identify Pollutants Prevent Pollution **The Universe** Nature's Pharmacy
 * The population is increasing, while the amount of available land is decreasing
 * The agriculture land needs to be as productive as possible
 * Factors that decrease productivity are poor soil, lack of water, weeds, plant diseases and pests that eat crops
 * Chemists can help with these problems by:
 * Chemicals designed to kill pests could also kill useful insects, so today chemicals are designed for specific problems. These chemicals are like the chemicals plants use to protect themselves.
 * Sometimes, chemists use chemicals produced by insects to fight pests.
 * Pollutant: a material found in air, water or soil that is harmful to humans or other organisms.
 * Chemists help identify pollutants and prevent pollution
 * Lead is an example of a pollutant, it was used by the Romans in their pipe system and wine bottles
 * They believe lead poisoning may have caused Roman rulers to make bad decisions
 * Lead was used in paints, gasoline and other products until the mid 1900s and they discovered in 1971 that a low amount of lead can be harmful to humans.
 * Low levels of lead in the blood can damage the nervous system of a child and can cause a reduced ability to learn
 * Lead paint was banned from houses in 1978, and today the major source of lead in children is from the houses that had been painted with lead paint before it was illegal. Children would touch the walls then the lead would transfer to theirs mouths off their fingers.
 * To prevent lead poisoning, it is advised to test children blood, regulate homes sales to families with children and public awareness of campaigns.
 * To study the universe, chemists gather data from afar and analyze the matter that is brought back to Earth
 * In 1868, Pierre Janssen discovered gas on the sun's surface which he named helium and in 1895, William Ramsay discovered helium on earth.
 * Scientists depend of matter brought back to earth to study the moon and planets.
 * Chemists have analyzed more than 850 lbs of moon rock brought back to earth.
 * 40% of all modern medicines come from chemicals produced by plants or animals
 * First they identify the active ingredient then purify it for human use.



** 1.3 Thinking like a Scientist ** Coeditor: Maddie Myers Member: Ali Fortier **Alchemy**
 * __alchemists__studied matter long before chemists
 * developed tools and techniques for working with chemicals
 * developed processes for separating mixtures and purifying chemicals
 * designed equipment (beakers, flasks, tongs, funnels)
 * they did NOT provide logical explanations for the changes in matter they observed
 * practical side: focuses on developing techniques for working with metals, glass, and dyes
 * mystical side: focuses on concepts like perfection
 * searched for a way to turn lead into gold (gold was seen as a perfect metal)

**The Scientific Method**
 * a logical, systematic approach to the solution of a scientific problem
 * __making observations__
 * using senses to obtain information
 * leads to a question
 * useful for problem solving because it is closely related to ordinary common sense
 * __testing hypothesis__
 * a proposed explanation for an observation
 * tested by an experiment
 * procedure that is used to test a hypothesis
 * **manipulated variables**: variable you change in an experiment (independent)
 * **responding variable**: variable that is observed during an experiment (dependent)
 * variables are relateable to one another
 * has to be a repeatable procedure
 * __developing theories__
 * **theory**: well-tested explanation for a broad set of observations
 * can never technically be proved, but it is still reliable
 * it just may change in the future to explain new observations/ results
 * __scientific law__
 * a concise statement that summarizes the results of many observations and experiments
 * does not try to explain the relationship it describes
 * the explanation requires a theory

** 1.4 Problem Solving in Chemistry ** Coeditor: Lauren O'Reilly Member: Kyle Gallagher

**Skills Used in Solving Problems**


 * Effective problem solving always involves coming up with a plan and then putting the plan into action.
 * Whether you are trying to solve the problem of which type of soda to buy or which product to buy because of ingredients, you will use the skills needed to solve problems.

1. __Analyze__: first, determine where you are starting from and where you are going 2. __Calculate__: through planning and analyzing, you should be able to calculate the answer. 3. Evaluate: after you finish the problem, double check Estimating Walking Time- walk from the Indiana State Capital to the Murat Centre 1. __Analyze:__ Knowns Unknowns This is a conversion problem where the first unit of measure, the blocks, needs to be the second unit of measure, the minutes. Divide the distance in blocks by the number of blocks in 1 mile to get the distance of the trip in miles. Then, multiple number of miles by the time it takes to walk one mile. 2. __Calculate__: Solving for the unknown 8 blocks X 1 mile/10 blocks = .8 mile .8 mile X 20 minutes/1 mile= 16 minutes 3. __Evaluate__: Ask yourself if the answer makes sense. Yes, it makes sense that it takes 16 minutes to walk 8 blocks.
 * Solving Numeric Problems **
 * Most problems in chemistry require some form of math.
 * possible examples of what is known could be a measurement or a relationship between measurements.
 * first you need to identify the known, where you are starting from, and the unknown, where you are going.
 * planning is the next step in analyzing, which is also one of the most important things in problem solving.
 * diagrams such as a table or graph can help see the relationship between the known and the unknown.
 * may need to convert a measurement from one unit to another
 * rearranging an equation can also help solve for the unknown
 * ask yourself questions like "Does this make sense?" or "Is the answer reasonable?"
 * always double check your work and make sure that you copied down the data correctly.
 * check that the final answer has the right unit and label
 * scientific notation can be used along with significant figures
 * Sample Problem **
 * the distance is 8 blocks
 * 10 city blocks = 1 mile
 * How many minutes will the trip take if you can walk one mile in 20 minutes?
 * distance to be traveled= 8 blocks
 * walking speed= 1 mile/20 minutes
 * 1 mile = 10 blocks
 * time of trip = ? minutes
 * Solving Conceptual Problems **

**Examples **
 * Conceptual problems are problems without numbers and ask you to apply concepts you are studying to new situations.
 * The steps for solving a conceptual problem are //analyze// and //solve//.
 * You still need to identify the known and unknown information and definitely need to make a plan.
 * Since there are no numbers, you do not need to check for units, make an estimate, or check calculations (because there are none). [[image:mrdschemistryhwiki/anylize_and_solve.PNG width="311" height="65"]]


 * Look at conceptual problem 1.1 on pg. 32 “Manny has to run 6 errands between 10 and 5 on Saturday. He must get a haircut, wash his car, buy stamps, rent a video, return a library book, and buy some groceries. Assume that each errand will take 30 min and that Manny will only do one errand per hour. Manny will stop for a lunch break between 12 and 1. Use the info in the drawing to figure out a way for Manny to accomplish all 6 tasks.”
 * Hours open: video store is 10am to 6pm, post office is 8am to 11am, barbershop is 10am to 3pm, library is 10am to 1pm, car wash is 10am to 4pm and supermarket is 7am to midnight.
 * 1) Analyze – Each place that Manny needs to visit is open for a limited number of hours on Saturday. Manny must do his errands between 10 and 12, and between 1 and 5. At a rate of one errand per hour, Manny must do 2 errands before lunch and 4 errands after lunch.
 * 2) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 16px;">Solve – The post office and library are open only in the morning. The barbershop and the car wash close earlier than the video store. The supermarket is open late. One possible order for the errands is post office, library, barbershop, car wash, video store, and supermarket.
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 16px;">For additional practice see pg. 32 #28 and 29.
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 16px;">Describe two alternative orders in which Manny could complete his errands.
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 16px;">What if Manny had 7 errands instead of 6? What would he need to do to adjust for the extra errand?

//** CHAPTER 3 **// ** 3.1 Measurements and their Uncertainty ** Coeditor: Brynna Harum Member: Jordyn Renaghan

**Using and Expressing Measurements** **Accuracy, Precision, and Error**
 * measurement-is a quantity that has both a number and a unit
 * fundamental to the experimental sciences
 * important to be able to make measurements and to decide whether a measurement is correct
 * International System of Units is used (SI)
 * Scientific Notation-a given number is written as the product of two numbers: a coefficient and 10 raised the the 10 power
 * 602,000,000,000,000,000,000,000 = 6.02 X 10E23
 * coefficient is 6.02, in scientific notation the coefficient is always a number equal too or greater than one and less then ten
 * **Accuracy**: a measurement of how close a measurement comes to the actual or true value of whatever is being measured
 * to evaluate the accuracy of a measurement, the measured value must be compared to the correct value
 * **Precision**: a measure of how close a series of measurements are to one another
 * to evaluate the precision of a measurement, you must compare the values of two or more repeated measurements



Example: (the boiling point measurement) percent error= { abs( 99.1 - 100.0) / 100.0 } x 100 { 0.9 / 100.0 } x 100 .009 x 100 0.9% **Significant figures in Measurement**
 * ** Error: ** the difference between the experimental value and the accepted value
 * experimental value: the value measured in the lab
 * accepted value: the correct value based on reliable references
 * ERROR = experimental value - accepted value
 * percent error: the absolute value of the error,divided by the accepted value, multiplied by 100%
 * __*see page 65 in the text book for other examples * __**
 * significant figure-in a measurement include all of the digits that are known, plus a last digit that is estimated
 * measurements must always be reported to the correct number of significant figures because calculated answers often depend on the number of significant figures in the values used in the calculation.
 * three meter stick can be used to make successively more precise measurements of the board
 * rules for determining whether a digit in a measured value is significant:
 * 1) every nonsero digit in a reported measurement is assumed to be significant
 * 2) zeros appearing between nonsero digits are significant
 * 3) leftmost zeros appearing in front of nonzero digits are not significant ut they act as placeholders
 * 4) zeros at the end of a number and to the right of a decimal point are always significant
 * 5) zeros at the rightmost end of a measurement that lie to the left of an understood decimal point are not significant if they serve as placeholders to show the magnitude of the number
 * 6) there are two situations in which numbers have an unlimited number of significant figures If you count 23 people in a room there are exactly 23 people with unlimited number of significant figures. The other situation is when dealing with numbers that are exactly defined quantities such as those found within a system of measurement

**Significant Figures in Calculations**
 * **Rounding:**to round a number you must determine how many significant digits you have in your answer. Once you have determined this, you round to that many digits counting to the left.
 * If the digit immediately to the right id less than five, it is simply dropped from the value, and the significant digit stays the same.
 * If the digit in question is greater than or equal to 5, the value of the digit in the last significant place is increased by 1

** 3.2 The International System of Units (SI) ** Coeditor: Abby White Member: Brittany Morgan **Measuring with SI Units** **Units of Length** **Units of Volume** i. The unit for volume is from the units of length. i. 10 cm X 10 cm X 10 cm = 1000cm3 = 1Liter
 * 1) Measurements all depend on units to serve as a reference standard.
 * In Science those reference standards are from the metric system.
 * Metric System is of easy use because it is universal and it goes by multiples of 10.
 * The International System of Units (SI) is a revised version of the metric system.
 * There are seven base units. Refer to diagram A.
 * The five SI units commonly used by chemists are the meter, kilogram, kelvin, second and the mole.
 * SI is the usual way to report results but due to circumstance non-SI units may be preferred.
 * Units and Quantities **
 * 1) Different quantities require different units.
 * 1) In SI the basic unit of length is the meter (m).
 * 2) For large and small lengths, it is easier to use a unit of length that has a prefix. Refer to diagram B.
 * Common metric units of length include the centimeter, meter and kilometer
 * Commonly Used Metric Prefixes ||
 * Prefix || Meaning || Factor ||
 * Mega (M) || 1 million times larger than the unit it precedes || 106 ||
 * Kilo (k) || 1000 times larger than the unit it precedes || 103 ||
 * Deci (d) || 10 times smaller than the unit it precedes || 10-1 ||
 * Centi (c) || 100 times smaller than the unit it precedes || 10-2 ||
 * Milli (m) || 1000 times smaller than the unit it precedes || 10-3 ||
 * Micro (µ) || 1 million times smaller than the unit it precedes || 10-6 ||
 * Nano (n) || 1000 million times smaller than the unit it precedes || 10-9 ||
 * Pico (p) || 1 trillion times smaller than the unit it precedes || 10-12 ||
 * 1) The space occupied by any sample of matter is called its volume.
 * To calculate volume, the equation is length (l) times width (w) times height (h).
 * 1) A more convenient volumetric measurement unit is the liter (L).
 * The liter is the volume of a cube that is 10 cm along each edge.
 * Because 1 L is 1000cm3 then 1 mL is equal to 1 cm3
 * 1) Common metric units of Volume include the liter, milliliter, cubic centimeter and microliter.
 * 2) To measure liquid volumes, there are many devices including graduated cylinders, pipets, burets, volumetric flasks and syringes.
 * Temperature is also brought into the equation, because the volume of any liquid, solid or gas changes with temperature.

-mass of an object is measured in comparison to the kilogram -the gram is 1/1000 of a kilogram -can use a platform balance to meausure mass -the unknown mass is equal to the sum of the standard masses -analytical balance: used to measure objects less than 100g -on earth you weigh 6 times more than you do on the moon -Weight: the force that measures the pull on a given mass by gravity *is a measure of force -mass remains constant
 * Units of Mass **

-Temperature is the measure of how hot or cold something is -things expand with an increase in temperature, but contract with a decrease -Celsius Scale: metric system scale, named after Anders Celsius; freezing point is 0 degrees and boiling is 100 degrees -Kelvin Scale: contains absolute value; freezing is 273.15, boiling is 373.15 -A change of one degree on the celsius scale is equivalent to one kelvin -0 kelvin is equal to absolute zero
 * Units of Temperature **
 * determines the direction of heat transfer
 * except water!!!

This is an example of a Kelvin Scale and Celsius Scale and how they compare to each other:

**Units of energy** -Solar panels convert radiant energy from the sun into electrical energy -Energy is the ability to do work and produce heat -The joule and the calorie are common units of energy -Joule:is the SI unit of energy -Calorie:is the quantity of heat that raises the temperature of 1g of pure water by 1 degree Celsius



** 3.3 Conversion Problems ** Coeditor: Andrea Vale Member: Ryan McSweeney

**Conversion Factors** -If you think about any number of everyday situations, you will realize that a quantity can usually be expressed in several ways.(Ex: 1 dollar=4quarters=10 dimes=20 nickels=100 pennies) -The same is true for scientific quanitities( 1 meter=10 decimeters=100 centimeters=1,000 millimeters) -A **conversion factor** is a ratioof equivalent measurements.The ratios 100cm/1m and1m/100cm are conversion factors. -In a conversion factor the numerator is equalivalent to the denominator. **The below is an example of a conversion factor.** **Key Note:** When a measwurement is multipluied bya conversion factor, the numerical value is generally changed, but the actual size of the quantity measured remains the same. -For example 1m and 10 dm are different ways of measuring the same thing. The relationship between grams is 1000 grams=1kg, so the conversion factor is 1000g/1kg and 1kg/1,000g

**Dimensional Analysis** **Dimensional analysis** is a way to analyze and solve problems using the units, or dimensions of the measurements.

**Using Dimensional analysis** How many seconds are in a workday that lasts exactly 8 hours? **Step 1 Analyze**(list the knowns and unknowns) **knowns** -time worked,8 hours -1 hour=60 mins -1 minute=60 seconds **Unknown** -Seconds worked **Step 2 Calculate** Then you set up the equation like this 8h x (60min/1 h) x (60s/1minute)=28,000 s= 2.8800 x 10 to the 4th power(s) **Step 3 Evaluate** The answer must have the desired unit(seconds). Since seconds is a small unit, you should expecta large number of seconds for 8 hours. So when you complete the problem you should have 28,800 seconds which is a large number so that sounds right. __**Example Video to Help With Dimensional Analysis**__ []

**Converting Between Units** 1. Analyze: Knowns: Mass = 750 dg Unknowns: Mass = ?dg 1 gram = 10 dg 2. Calculate: (1 gram/ 10 dg) x ( x/ 750 dg) = 75 grams
 * In chemistry, you often need to express a measurement in a unit different from the one given or measured initially
 * Problems in which a measurement with one unit is converted to an equivalent measurement with another unit are easily solved using dimensional analysis
 * Example: Express 750 dg (decigrams) in grams

3. Evaluate: Does the answer make sense? Because the unit gram represents a larger mass than the unit decigram, it makes sense that the number of grams is less than the given number of decigrams.

**Multistep Problems** 1. Analyze: Knowns: Length = 0.073 cm = 7.3 x 10-2 cm Unknown: Length = ? micrometers 102 cm = 1 m 1 m =106 micrometers
 * Many complex word problems are more easily solved by breaking the solution down into steps
 * When converting between units, it is often necessary to use more than one conversion factor
 * Example: What is 0.073 cm in micrometers?

2. Calculate: Centimeters --> Meters --> Micrometers (7.3 x10-2 cm ) x ( 1 m /102 cm ) x (106 micrometers/ 1 m) = 7.3 x 102 micrometers

3. Evaluate: Does the answer make sense? Because a micrometer is much smaller than a cm, it makes sense that the answer be numerically larger than the given measurement.

**Converting Complex Units** Knowns: Density of manganese = 7.21g/cm3 Unknowns: Density of manganese = ? kg/m3 103g = 1 kg 106 cm3 = 1 m3
 * Many common measurements are expressed as a ratio of two units
 * Using dimensional analysis, converting these complex units is easy, it just takes multiple steps to arrive at an answer
 * Example: The density of manganese, a metallic element, is 7.21g/cm3. What is the density of manganese expressed in units kg/m3?
 * 1. Analyze: **

**2. Calculate** : (7.21 g/ 1 cm3) x ( 1 kg/ 103g) x (106 cm3/ 1 m3) = 7.21 x 103 kg/m3

**3. Evaluate**: Does the answer make sense? Because the physical size of the volume unit m3 is so much larger than cm3, the calculated value of the density should be larger than the given value even though the mass unit is also larger.

** 3.4 Density ** Coeditor: Jordyn Majka Member: Nikki Steiner

Determining Density __Density__ - The ratio of the mass of an object to its volume. It is calculated with a simple formula:



Example: A 10.0 cm3 (volume) piece of lead weighs 114 g (mass). What's the density? 114 g/10.0 cm = 11.4 g/cm3


 * An important point to remember is that density is an intensive property that depends only on the composition of a substance, not on the its size!!**

Mixing liquids with different densities results in the lighter liquid floating on top of the heavier liquid (like water and oil). Gases work the same way. Gases lighter than oxygen itself with float up (like a helium-filled ballon).

For a more detailed explanation of density, you can check out this video! @http://www.youtube.com/watch?v=Q4EBOE4pJyw