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Period G



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external image 220px-Chemicals_in_flasks.jpg external image chemsolu.gifexternal image carpenters-rule.jpg

Vocabulary: Roll over for definition or see the caption below each.
ABSLOUTE ZERO:the point where no more heat can be removed from a system, according to the absolute or thermodynamic temperature scale
ABSLOUTE ZERO:the point where no more heat can be removed from a system, according to the absolute or thermodynamic temperature scale
ACCEPTED VALUE: the closeness of a measurement to the true value of what is being measured
ACCEPTED VALUE: the closeness of a measurement to the true value of what is being measured
ACCURACY:the closeness of a measurement to the true value of what is being measured
ACCURACY:the closeness of a measurement to the true value of what is being measured
ANALYTICAL CHEMISTRY:the study of the chemical composition of natural and artificial materials
ANALYTICAL CHEMISTRY:the study of the chemical composition of natural and artificial materials
APPLIED CHEMISTRY: research that is directed toward a practical goal or application
APPLIED CHEMISTRY: research that is directed toward a practical goal or application
BIOCHEMISTRY:The study of the chemical substances and vital processes occurring in living organisms; biological chemistry; physiological chemistry
BIOCHEMISTRY:The study of the chemical substances and vital processes occurring in living organisms; biological chemistry; physiological chemistry
CALORIE: a unit of heat equal to the amount of heat required to raise the temperature of one kilogram of water by one degree at one atmosphere pressure
CALORIE: a unit of heat equal to the amount of heat required to raise the temperature of one kilogram of water by one degree at one atmosphere pressure
CELSIUS SCALE: pertaining to or noting a temperature scale (Celsius scale) in which 0° represents the ice point and 100° the steam point
CELSIUS SCALE: pertaining to or noting a temperature scale (Celsius scale) in which 0° represents the ice point and 100° the steam point
CHEMISRTY:the science of matter; the branch of the natural sciences dealing with the composition of substances and their properties and reactions
CHEMISRTY:the science of matter; the branch of the natural sciences dealing with the composition of substances and their properties and reactions
CONVERSION FACTOR:factor by which a quantity that is expressed in one set of units must be multiplied in order to convert it into another set of units
CONVERSION FACTOR:factor by which a quantity that is expressed in one set of units must be multiplied in order to convert it into another set of units
DENSITY: Mass per unit volume
DENSITY: Mass per unit volume
DIMENTIONAL ANALYSIS: a technique of problem-solving that uses the units that are part of a measurement to help solve the problem
DIMENTIONAL ANALYSIS: a technique of problem-solving that uses the units that are part of a measurement to help solve the problem
ENERGY:the power used to overcome resistance or to change
ENERGY:the power used to overcome resistance or to change
ERROR:the difference between the experimental value and the accepted value in an experiment
ERROR:the difference between the experimental value and the accepted value in an experiment
EXPERIMENT:a scientific procedure undertaken to make a discovery, test a hypothesis, or demonstrate a known fact
EXPERIMENT:a scientific procedure undertaken to make a discovery, test a hypothesis, or demonstrate a known fact
EXPERIMENTAL VALUE:the value calculated from the data in a given lab experiment
EXPERIMENTAL VALUE:the value calculated from the data in a given lab experiment
GRAM: a metric unit of mass or weight equal to 15.432 grains; one thousandth of a kilogram
GRAM: a metric unit of mass or weight equal to 15.432 grains; one thousandth of a kilogram
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HYPOTHESIS: a proposition, or set of propositions, set forth as an explanation for the occurrence of some specified group of phenomena
INORGANIC CHEMISTRY:The study of subtances that generally do not contain carbon. It is found in non-living things like rocks
INORGANIC CHEMISTRY:The study of subtances that generally do not contain carbon. It is found in non-living things like rocks
INTERNATIONAL SYSTEM OF UNITS(SI):The revised version of the metric system, adopted by international agreement in 1960
INTERNATIONAL SYSTEM OF UNITS(SI):The revised version of the metric system, adopted by international agreement in 1960
JOULE:the SI unit of energy; 4.184 J equal one calorie (3.2)
JOULE:the SI unit of energy; 4.184 J equal one calorie (3.2)
KELVIN SCALE:a scale used to measure the absolute temperature
KELVIN SCALE:a scale used to measure the absolute temperature
KLOGRAM:the base unit of mass in the International System of Units (SI),which is the modern standard governing the metric system; the mass of 1 Liter of water at 4 degrees Celcius, it is the base unit of mass in SI
KLOGRAM:the base unit of mass in the International System of Units (SI),which is the modern standard governing the metric system; the mass of 1 Liter of water at 4 degrees Celcius, it is the base unit of mass in SI
LITER:the common unit of volume in the metric system; the volume of a cube measuring 10 centimeters on each edge
LITER:the common unit of volume in the metric system; the volume of a cube measuring 10 centimeters on each edge
MACROSCOPIC:able to be seen or examined by the unaided eye
MACROSCOPIC:able to be seen or examined by the unaided eye
MANIPULATED VARIABLE: what is changed purposely throughout the experiment; it is what you're observing
MANIPULATED VARIABLE: what is changed purposely throughout the experiment; it is what you're observing
MEASURMENT: In science, measurement is the process of obtaining the magnitude of a quantity, such as length or mass, relative to a unit of measurement
MEASURMENT: In science, measurement is the process of obtaining the magnitude of a quantity, such as length or mass, relative to a unit of measurement
METER: The base unit of length in the international system of units. It is used to measure the distance between two points
METER: The base unit of length in the international system of units. It is used to measure the distance between two points
OBSERVATION: information gathered by a person's senses (usually includes measurements). This is the first step in the Scientific Method process
OBSERVATION: information gathered by a person's senses (usually includes measurements). This is the first step in the Scientific Method process
ORGANIC CHMISTRY:a branch of chemistry that involves the study of compounds that contain carbon(often substances produced by living organisms)
ORGANIC CHMISTRY:a branch of chemistry that involves the study of compounds that contain carbon(often substances produced by living organisms)
PERCENT ERROR: the percent that a measured value differs from the accepted value
PERCENT ERROR: the percent that a measured value differs from the accepted value
PHYSICAL CHEMISTRY: the branch of chemistry dealing with the physical properties of chemical substances
PHYSICAL CHEMISTRY: the branch of chemistry dealing with the physical properties of chemical substances
POLLUTANT: A material found in air, water, or soil that is harmful to humans and other organisms
POLLUTANT: A material found in air, water, or soil that is harmful to humans and other organisms
PERCISION: describes the closeness, or reproducibility, os a set of measurements taken under the same conditions
PERCISION: describes the closeness, or reproducibility, os a set of measurements taken under the same conditions
PURE CHEMISTRY: the pursuit of chemical knoweldge for its own sake
PURE CHEMISTRY: the pursuit of chemical knoweldge for its own sake
RESPONDING VARIABLE: the variable that is observed during an expiriment; also called the dependent variable
RESPONDING VARIABLE: the variable that is observed during an expiriment; also called the dependent variable
SCIENTIFIC METHOD: a method of investigation involving observation and theory to test scientific hypotheses
SCIENTIFIC METHOD: a method of investigation involving observation and theory to test scientific hypotheses
SCIENTIFIC LAW: a concise statment that summerizes the results of many observations and experiments
SCIENTIFIC LAW: a concise statment that summerizes the results of many observations and experiments
SCIENTIFIC METHOD: A logical, systematic approach of a scientific problem; steps of scientific method inc. -making observations -testing hypothesis -developing theories
SCIENTIFIC METHOD: A logical, systematic approach of a scientific problem; steps of scientific method inc. -making observations -testing hypothesis -developing theories
SCIENTIFIC NOTATION: also known as standard form or as exponential notation, is a way of writing numbers that accommodates values too large or small to be conveniently written in standard decimal notation
SCIENTIFIC NOTATION: also known as standard form or as exponential notation, is a way of writing numbers that accommodates values too large or small to be conveniently written in standard decimal notation
SCIENTIFIC FIGURES: all the nonzero digits of a number and the zeros that are included between them or that are final zeros and signify accuracy: The significant digits of 0.01230 are 1, 2, 3, and the final 0, which signifies accuracy to five places
SCIENTIFIC FIGURES: all the nonzero digits of a number and the zeros that are included between them or that are final zeros and signify accuracy: The significant digits of 0.01230 are 1, 2, 3, and the final 0, which signifies accuracy to five places
TECHNOLOGY: the means a society provides its members with needed and desired
TECHNOLOGY: the means a society provides its members with needed and desired
TEMPERATURE: measure of the warmth or coldness of an object or substance with reference to some standard value
TEMPERATURE: measure of the warmth or coldness of an object or substance with reference to some standard value
THEORY: A well-substantiated explanation of some aspect of the natural world; an organized system of accepted knowledge that applies in a variety of circumstances to explain a specific set of phenomena
THEORY: A well-substantiated explanation of some aspect of the natural world; an organized system of accepted knowledge that applies in a variety of circumstances to explain a specific set of phenomena
WEIGHT: the amount or quantity of heaviness or mass; amount a thing weighs
WEIGHT: the amount or quantity of heaviness or mass; amount a thing weighs

==Group 1
==
Co-editor: Lauren Altmeyer

Group Members: Abby John, Grayce Rose, and Lauren Altmeyer
==(What is Chemistry? Pgs. 7-11)
==

===Intro to Chemistry

=

===(Abby John pgs. 7-8)

=

===Chemistry is the study of matter and the changes it undergoes.

=

  • matter is anything with mass
  • because living and non living things are made up of matter chemistry affects many parts of life

There are five traditional types of chemistry

  • organic chemistry-the study of chemicals containing carbon
  • inorganic chemistry-the study of chemicals not containing carbon
  • biochemistry- the study of the chemical processes in the body
  • analytical chemistry- the study of the composition of matter

  • physical chemistry-the study that deals with mechanism, rate and energy transfer that occurs when matter changes

Pure and Applied Chemistry

(Lauren Altmeyer pg. 9)


VOCAB


Pure Chemistry- Pursuit of chemical knowledge for your own sake

Applied Chemistry- Research directed towards a goal

Technology- The means by which society provides it members with those things needed and desire


  • Pure research can lead to a goal, but a goal can exist before research is done to explain how it works (nylon and aspirin are examples of this)
nylon_485.jpg
Nylon



NYLON


Can be used for:
  1. Fabric
  2. Jackets
  3. Fishing lines
  4. Toothbrush bristles
  5. Ropes
  • Can be drawn from long, thin, silk-like fibers

ASPIRIN
aspirin325.jpg
aspirin325.jpg

Used to:

  1. Relieve pain
  2. Prevent heart attacks
  3. Block blood clots from forming
  • Blocks a group of chemicals that cause pain
  • Prescribed by some doctors to take a daily does if you are at risk for heart attack


TECHNOLOGY

  • Allows humans to do things more quickly with less effort
  • Allows people to do things that would other wise be impossible, such as going to the moon

===Why study chemistry?

=

(Grayce Rose pgs. 10-11)

Studying chemistry can be useful in many ways.
It is useful when:
  • explaining the natural world-to satisify our own curiosity
  • preparing for a career-not only including in the field of science:
    • firefighters need to know which types of chemicals to use to fight fires
    • turf managers and groundskeepers need to have a knowledge of ground chemistry
    • photographeruse chemicals to develop pictures
  • being and informed citizen-with knoweldge of chemistry we are likely to make more informed decisions
    • supporting and funding scientific research can help make new advances in technology
    • it is important to be informed about the research befor supporting it




Group 2

Co-Editor:Kim Kogut

Group Members: Kelsey Sullivan, Lauren Bedard, Kim Kogut

Chapter Section (Pgs 12-19)


==Chemistry Far and Wide
==
===Materials and Energy pgs 12 & 13 (Kelsey Sullivan)

=


====Materials:

==

  • Chemists design materials to fit specific needs
    • In 1948 George de Mastrel was hiking and picked up on of the burrs that was stuck to his clothing. He found that every burr was covered with tiny loops that could latch themselves to the loops in woven clothing.
    • In 1955 George designed a tape that resembled the burrs. It was called hook-and-loop tape.
  • Scientists look at the world in two ways:
    • Macroscopic:
      • The world of objects large enough for you to see with without magnification.
    • Microscopic:
      • The world of objects that can only be seen under magnification.

====Energy:

==

  • Energy is necessary to meet the needs of modern society.
  • The demand for energy continues to increase witht industrialization growing.
  • There are two ways to meet the demand for energy:
    • Conservation:
      • The easiest way to conserve energy is through insulation
      • Insulation acts as a barrier to heat flow from the inide of a house or the outside of a freezer.
      • Chemists have created SEAgel
      • SEAgel is a foam made from seaweed that is so light it can float on bubbles.
    • Production:
      • Burning coal, petroleum, and natural gas is a great source of energy.
      • They are called fossil fuels because they are formed from remains of ancient plants and animals.
      • Fossil fuels are a limited supply.
      • Scientists are trying to obtain fuels from plants
      • Oil from soy beans is used to make biodiesel.
    • Storage:
      • Batteries are a good example of energy storage:
      • They use chemicals to store energy that is released as electric current when the batteries are used.
      • Batteries can be recharged. Rechargeable batteries are used in cordless tools
      • NASA uses cordless tools to drill on the moon.
      • Rechargeable batteries are also used for things like camera's, wireless phones, and laptop computers.

===The Environment and the Universe

=

===pgs. 16-17 (Lauren Bedard)

=


The Environment:


  • New technologies cause pollutants
    • Pollutants: Material found in air, water, or soil that is harmful to humans or other organisms
  • Chemists help identify pollutants and prevent pollution
  • Identify Pollutants:
    • Lead can cause issues in the brain and other serious problems especially in children
    • Low levels of lead in blood can cause permanent damage
  • Prevent Polution:
    • Use of lead was banned in the late 1900’s
    • There is still lead in millions of houses built before 1978
    • Prevent lead poisioning by:
      • Testing children’s blood for lead
      • Regulating sales of homes to families with young children
      • Raising public awareness on the issue

The Universe:


  • To study the universe, chemists gather data from afar and analyze matter that is brought back to Earth
  • 1800’s- scientists begin to study the composition of stars
  • Helium:
    • Peirre Janssen: discovered it on sun’s surface
    • Norman Lockyer: named it
    • William Ramsay: discovered it on Earth
  • Scientists depend on matter brought back to earth by astronauts to study moon/planets


Medicine, Biotechnology, and Agriculture

pg 14-15 Kim Kogut


Chemistry supplies medicines, materials, and technology that doctors use.

  • medicines such as perscription drugs are enginereed from chemistry
  • materials suh as used for repairs in the body are created through chemistry
  • biotehnology applies science to the production of biological products
Chemists help find safer and more productive ways to grow crops.

  • chemists help increase productivity and decrease poor soil quality, weeds, lack of water, diseases and pet problems
  • they genetically modify some plants so that they will thrive
  • farmers used to create chemicals to protect plants from preditors
  • chemists help create safer versions of pest prevention



Group 3

Co-Editor: Brendan Lynch

Group Members: Lindsey Bedrosian, Brendan Lynch and Emily Taylor

Chapter Section (Pgs 20-27)

=

Thinking Like A Scientist, Pages 20-21 (Lindsey Bedrosian)

I. Thinking Like A Scientist

A. Alexander Fleming

1. Scottish Scientist

2. 1928-noticed bacteria didn’t grown on mold

a. Assumed that mold released a chemical that prevents the growth of bacteria

b. Chemical=penicillin

c. 1945- Shared a noble prize with Howard Florey and Ernst Chain who helped isolate penicillin

B. Alchemy

1. The word chemistry comes from the word alchemy

a. Alchemy is the study of matter

b. Practiced in China and India as early as 400 B.C.

2. Alchemy has 2 sides a. Practical

1. Focused on developing techniques by working with metals glass and dyes

b. Mystical

1. Focuses on concepts like perfection

a. Ex. Gold is considered a perfect metal-tried to transform lead into gold

C. All Chemists…

1. Developed the Tools and Techniques for working with chemicals

2. Developed processes for separating mixtures and purifying chemicals

3. Designed beakers, flasks, tongs, funnels, mortar and pestle II. An Experimental Approach to Science

A. 1500’s-shift from Alchemy to Science

B. Science spread in Britain due to King Charles II

1. Allowed Royal Society of London for the Promotion of Natural Knowledge to form

2. Scientists met and discussed scientific ideas and conducted experiments

3. Their aim was to encourage scientists to base their conclusions about the natural world on experimental evidence rather than widely accepted ideas

C. Antoine-Laurent Lavoisier

1. Helped transform chemistry from science of observation to science of measurement

2. Created a balance that could measure mass to the nearest .0005 gram

3. Settled the longstanding debate on how materials burn a. Previously, people thought that things burn because they contain phlogiston

b. He proved things needed oxygen to burn

4. 1794- Arrested, and killed due to his involvement in the taxation D. Marie Ann Lavoisier

1. Helped with her husband’s experiments

a. Drew pictures of his work and translated his papers from English

=


Scientific Method, pages 22-23 (Brendan Lynch)

The scientific method refers to a body of techniques that are used to answer questions.

  • created by Roger Bacon
  • used by all scientists
  • used to develop and test theories
  • used to make scientific laws

Steps


  1. Define the question
  2. Gather information and resources (observe)
  3. Form hypothesis
  4. Perform experiment and collect data
  5. Analyze data
  6. Interpret data and draw conclusions that serve as a starting point for new hypothesis
  7. Publish results
  8. Retest (frequently done by other scientists)

|| Steps of the Scientific Method || Detailed Help for Each Step ||

  • || Ask a Question: The scientific method starts when you ask a question about something that you observe: How, What, When, Who, Which, Why, or Where?
  • And, in order for the scientific method to answer the question it must be about something that you can measure, preferably with a number.
  • || Do Background Research: Rather than starting from scratch in putting together a plan for answering your question, you want to be a savvy scientist using library and Internet research to help you find the best way to do things and insure that you don't repeat mistakes from the past.
  • || Construct a Hypothesis: A hypothesis is an educated guess about how things work:
  • "If _[I do this] _, then _[this]_ will happen."You must state your hypothesis in a way that you can easily measure, and of course, your hypothesis should be constructed in a way to help you answer your original question.
  • || Test Your Hypothesis by Doing an Experiment: Your experiment tests whether your hypothesis is true or false. It is important for your experiment to be a fair test. You conduct a fair test by making sure that you change only one factor at a time while keeping all other conditions the same.You should also repeat your experiments several times to make sure that the first results weren't just an accident.
  • || Analyze Your Data and Draw a Conclusion: Once your experiment is complete, you collect your measurements and analyze them to see if your hypothesis is true or false.Scientists often find that their hypothesis was false, and in such cases they will construct a new hypothesis starting the entire process of the scientific method over again. Even if they find that their hypothesis was true, they may want to test it again in a new way.
  • || Communicate Your Results: To complete your science fair project you will communicate your results to others in a final report and/or a display board. Professional scientists do almost exactly the same thing by publishing their final report in a scientific journal or by presenting their results on a poster at a scientific meeting.



Collaboration and Communication , Pgs. 24-25 (Emily Taylor)

- When scientists collaborate and communicate, they increase the likelihood of a successful outcome.

  • Collaboration
    • Each scientist brings different knowledge or a different approach to solve a problem.
    • Collaborating is helpful when you need different insights on a particular problem.
    • Collaboration isn't always easy.
      • Conflicts about the use of resources, the amount of work, who should receive the credit and when and what information should be published is a lot of material these scientists need to work out.
  • Communication
    • In earlier centuries, scientists would exchange information through letters, or they would form societies to discuss their latest work.
      • These societies began to publish journals of the scientists' work.
    • Now, many scientists work together so they can communicate with each other face to face.
    • Many new ideas are exchanged through e-mail, by phone, or at international conferences.
    • The most reliable source of information about new discoveries are the scientific journals which are still published.
      • Readers and reviewers can challenge the scientist's conclusion or ask about the design of the experiment.
    • Now, the internet is a major source of information.
      • Everyone can get access to information on the Web.
      • Anyone can also post information to the web without getting it reviewed first.
      • You should always check the source of the information to make sure it is accurate.

Group 4

Co-editor: Hannah Valley
Group Members: Seamus Cuddy, Anne O'Toole, and Hannah Valley

Chapter 1 Section 4 (Pgs. 28-32)Problem Solving in Chemistry

Skills Used in Problem Solving (Hannah Valley)
  • Most people do not realize that you use problem solving techniques many times a day
  • Examples:
~In the grocery store, there are two brands of one item. How do you decide which brand to purchase?
~You are driving to work and you are already late. Which route would you take, the one that has traffic but is a shorter distance, or the one that is clear of any backup but may be farther?
~You are planning a party. Which appetizer do you think the majority of the guests would like better?

external image s_rubik-cube.jpg

Solving Numeric Problems (Anne O'Toole)
  • Backround Infomation
    • Measurement is a very important part of chemistry.
    • Most word problems in chemistry require math.
    • For a numeric word problem, the steps for solving are; analyze, calculate, and evaluate.
  • Analyze
    • First, determine where you are starting from (what you know) and where you are going to go (what you don't know).
    • You must plan out the problem to be successful.
    *You might want to draw a diagram, table, or graph.*
    • Now, select a equation that you can use to find the unknown. You can check in the Math Handbook that starts on page R56 for help with equations and math.
  • Calculate
    • This is usually the easiest part of solving a numeric problem.
    • You may need to convert a measurement from one unit to another unit.
    • You also may need to rewrite an equation before you can solve for the unknown.
  • Evaluate
    • After you find an answer evaluate it. This means making sure the answer makes sense, and checking to see if the answer is reasonable. If not, reread the word problem. Make sure that you chose the right equation and that you copied all the data correctly.
    • Check that your answer has the right unit and the correct amount of significant figures.
    • You might need scientific notation in your answer. That is in Chapter 3.


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Solving Conceptual Problems (Seamus Cuddy)

Not every word problem in Chemistry requires calculations...
Conceptual Problems = Nonnumeric Problems
numbers2.gif


THE SOLVING:
Basics
Identify what is known and unknown,
Make a plan to get from known to unknown
New For the Conceptual Problems
No need to...
Check the Units,
Make an Estimate, or
Check Your Calculations.

Just Two Steps...
1) Analyze
2) Solve

Numerical Problems VS. Conceptual Problems:
Numerical Problems require you to deal in numbers, doing things like converting measurements from unit to unit or rearranging an equation. Also, numerical problems require evaluating your answer if it is reasonable. Conceptual problems eliminate these numbers. You are required to solve a conceptual problem by just analyzing it and then solving it. It is very straightforward; right or wrong.


==Group 5
==
Co-editor: Colleen Fitzgerald

Group Members: Colleen Fitzgerald and David O'Brien

Chapter 3 Section 1 (pages 63-72)


Using and Expressing Measurement


  • Measurement is a qualitative description that includes both a number and a unit.
  • - Units are usually measured acoording to the International System of Units (SI)
  • - Below is a chart of the SI base units and the quantities they measure for.


Unit
Symbol

Measured Property
meter
m
,
length
kilogram
kg

mass
second
s

time
ampere
A

electric current
kelvin
K

thermodynamic temperature
mole
mol

amount of substance
candela
cd

luminous intensity
  • Scientific Notation: a given number is written as the product of two numbers- a coefficent and 10 raised to a power
  • The co-efficent must always be greater then 1 and less then 6
  • - Example- 602,000,000,000,000,000,000,000 = The coefficent would be 6.02 and then you would multiply 10 to the 23rd power
    • Accuracy , Prescision, and Error
  • Accuracy: the measure of how close a measurement comes to the actual or true value of whatever is being measured
  • Precision: the measure of how close a series of measure ments are to one another
  • For accuracy you must compare the measured value to the correct value
  • For precision you must compare two or more values of a repeated measurement
  • Example: Using Darts with Accuracy and Precision
  • 1. 3 darts land close together on the bullseye= good accuracy and precision
  • 2. 3 darts land near eachother but not on the bullseye= good precison but not accuracy
  • 3. 3 darts land far apart and not on the bullseye= poor accuracy and precision
  • Accepted Value: correct value based on reliable refrences
  • Experimental Value: value measured in a lab
  • Error= experimental value subtracted from the accepted value
  • Percent Error= Error didvided by the accepted value x 100%
    • Signinficant Figures in Measurement
  • Signinficant Figures: a measurement that includes all of the digits that are known, plus a last didgit that is estimated
  • Example: Something between 2.4 and 2.5 pounds might be 2.46. 2 and 4 are known with certainty but the 6 is estimated
  • Determining Significant Figures
1. If it is a nonzero number its significant.


2. Leftmost zeros that appear before nonzero didgits and are not significant



3. Zeros between nonzero numbers are significant.



4. Zeros at the end of a number and to the right of a decimal point are significant.



5. Zeros at the rightmost end of a measurement aren't significant.



6. Exact numbers have an unlimited number of siginificant figures.


Accuracy, Precision, and Error

David O' Brien

Rounding


1. Determine how many significant figures the number has.


2. Round to that many digits.

3. Drop the last significant figure if it is less then 5.

Rounding Answers in Addition & Subtraction Problems

1. Answers in these problems need to be rounded off.

2. You round the answer to the same number of decimal places, in the measurement taken with the least digits.

3. ex.) 36.231 + 63.43 + 18.6253 = 118.2863 (When rounded the answer comes to 118.27)

4. This is becasue the 63.43 only has two digits to the right of the decimal point which is the least in each factor of the equation so you round the answer to the same number of digits.

5. ex.) 42.389 - 31.36621 = 11.02279 (When rounded the answer comes to 11.023)

6. ex.) 6.2783 + 8.289 + 1.227 = 15.7943 (When rounded the answer comes to 15.794)

Rounding Answers in Multiplication & Division Problems

1. Answers from these problems need to be rounded off.

2. You round the answer to the same number of significant figures, in the measurement with the least number of significant figures.

3. ex.) 3.518 x .62 = 2.18116 (When rounded the answer comes to 2.18)

4. This is because the .62 has two significant figures which is the least amount of significant figures in both factors, so you use the same amount in your rounded answer.

5. ex.) 8.234 x 6.3417 = 52.2175578 (When rounded the answer comes to 52.217)

6. ex.) 10.586862 / 4.29 = 2.4678 (When rounded the answer comes to 2.47)


Group 6


Co-editer: Marybeth Nametz
Group Members: Marybeth Nametz and
Alex Fischbach

Section 3.2: The International System of Units (pgs 73-79)


The International System of Units
external image table1.4.gif
external image table1.4.gif



external image table1.5.gif
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*Volume of any solid, liquid or gas(especially!) will change with temperature...
... to be accurate volume-measuring devices are taken at a given temperature-usually room temp. (20 degress Celsius)

Units of Mass

- Mass of an object is measure in comparison to a standard mass of 1 kg
-Kg: Basic SI unit of Mass
- Originally defined as the mass of 1 L of liquid water at 4 degree Celsius
- Gram: is 1/1000 of a kg
- The mass of 1 cm3 of water at 4 degree Celsius is 1 gram
- Common Metric Units of Mass: include the kg, g, mg, and microgram
- Platform balance: measure mass of an object
- Beam balanced at level
- Unknown mass = sum of standard mass
- Analytical balance: Measures objects of less than 100g and determine mass to the nearest 0.1 mg
- Moon: weigh 1/6 of what you weigh on earth
- Gravity
- Weight: Measures the pull n a given mass by gravity
- Changes
- Mass: Measure of the quantity of matter
- Remains consistent


Units of Temperature
-
Measure of how hot or cold an object is
- Determines the direction of heat transfer
- Heat transfers to the colder temperature
- Increase temperature: Objects expand
- Decrease: Contract (except water)
- Celsius: Sets the freezing point of water at 0 degrees Celsius and the boiling point of water at 100 degrees Celsius.
- Named after Anders Celsius
- Kevin Scale: The freezing point of water is 273.15 kelvins, and the boiling point is 373.15 K.
- “Absolute scale”
- Lord Kevin
- Absolute zero = 273.15 degrees Celsius
- A change of one degree on the Celsius scale is equal to one Kelvin on the Kelvin scale
- K = C + 273
- C = K -273


Units of Energy
-
Capacity to do work or to produce heat
- Joule and calorie are common units of energy
- Joule: SI unit of energy
- Cal: Quantity of heat that raises the temperature of 1 g of pure water by 1 degree Celsius.
- 1J = 0.2390 cal
-1 Cal = 4.184 J

Alex Fischback

Units of Mass

- Mass of an object is measure in comparison to a standard mass of 1 kg

-Kg: Basic SI unit of Mass


- Originally defined as the mass of 1 L of liquid water at 4 degree Celsius


- Gram: is 1/1000 of a kg

- The mass of 1 cm3 of water at 4 degree Celsius is 1 gram

- Common Metric Units of Mass: include the kg, g, mg, and microgram

- Platform balance: measure mass of an object

- Beam balanced at level

- Unknown mass = sum of standard mass

- Analytical balance: Measures objects of less than 100g and determine mass to the nearest 0.1 mg

- Moon: weigh 1/6 of what you weigh on earth

- Gravity

- Weight: Measures the pull n a given mass by gravity

- Changes

- Mass: Measure of the quantity of matter

- Remains consistent

- Units of Temperature: Measure of how hot or cold an object is

- Determines the direction of heat transfer

- Heat transfers to the colder temperature

- Increase temperature: Objects expand

- Decrease: Contract (except water)

- Celsius: Sets the freezing point of water at 0 degrees Celsius and the boiling point of water at 100 degrees Celsius.

- Named after Anders Celsius

- Kevin Scale: The freezing point of water is 273.15 kelvins, and the boiling point is 373.15 K.

- “Absolute scale”

- Lord Kevin

- Absolute zero = 273.15 degrees Celsius

- A change of one degree on the Celsius scale is equal to one Kelvin on the Kelvin scale

- K = C + 273

- C = K -273

- Energy: Capacity to do work or to produce heat

- Joule and calorie are common units of energy

- Joule: SI unit of energy

- Cal: Quantity of heat that raises the temperature of 1 g of pure water by 1 degree Celsius.

- 1J = 0.2390 cal

-1 Cal = 4.184 J




=Group 7
=
Co-Editor- Julia McNamara
Group Members- Meghan Faber and Julia McNamara

===Conversion Problems p. 80-87

=

  • a conversion factor is a ratio of equivalent measures
  • when a measure is multiplied by a conversion factor the numerical value is generally changed but the actual size is the same
  • to form a ratio to convert a measure the larger unit is the numerator and the smaller measure is the denominator
  • dimentional analysis is a way to analyze and solve a problem usins units of a measurment

Conversion Factors

By: Julia McNamara
  • A quantity can be expressed in many different ways. (1 meter= 10 decimeters= 100cm= 100mm)
  • Whenever 2 measurements are equal, a ratio of the two measurements would equal 1
A conversion factor is a ratio of equivalent measurements.
  • measurements of the numerator=measurements of the denominator

smaller number ---> 1 meter <---- larger unit
larger number ---> 100 cm <---- smaller unit

  • When a measurement is multiplied by a conversion factor, the numerical value is generally changed, but the actual size of the quantity measured remains the same.

Dimensional analysis:




===Converting Between Units:

=

By: Meghan Faber

You can use dimensional analysis in a problem when you have to make the units in a problem the same.


====Converting Between Metric Units:

==

Example: Convert 750dg into grams.


====First, Analyze: List what you do know and what you don't know.

==

Know-
Mass=750dg
1 gram= 10dg

Don't know-
Mass of 750dg in grams.

Since 10dg=1g, multiply the mass by the conversion factor: 1g/10dg (*Known unit in the denominator [bottom] and unknown is in the numerator [top])


====Second, Calculate:

==

750dg X 1g/10dg = 75 g (Notice the "dg"'s cancel out)


====*Make sure that the numbers make sense. For this problem, grams are bigger than decigrams (dg) so the mass number in grams should be less than in decigrams. (75<750 BUT 75g=750dg)

==


====Converting Between Metric Units with more than one conversion:

==

Example: Convert .073 cm into micrometers.

====First, Analyze: List what you know and what you don't know.

==

Know:
length= .073cm micrometers
Since you need to go from centimeters to meters to micrometers, you need to make sure when you multiply, all of the units cancel out except for micrometers.
Second, Calculate:
in scientific notation- 7.3 X 10^ -2 cm X 1m/10^2 cm X 10^6 micrometers/1m = 7.3 X 10^2 micrometers
not in scientific notation- .073cm X 1m/100cm X 1,000,000 micrometers/1m = 730 micrometers
(notice how meters and centimeters cancel out)
*Again, make sure the numbers make sense. For this problem, micrometers are smaller than centimeters, so the number of micrometers should be more than in centimeters.
Converting Ratios of Units
Converting ratios, is converting a set of two units.
Example: Convert 7.21g/cm^3 to kg/m^3
First, Analyze: List what you know and what you don't know.
Know-
density=7.21g/cm^3
10^3 (1,000) g/1kg
10^6 (1,000,000) cm^3 = 1m^3
Unknown-
density in kg/m^3
In this problem, grams (g) needs to change to kilograms (kg), and centimeters (cm) needs to change to meters (m).
Second, Calculate:
in scientific notation: 7.21g/1cm^3 X 1kg/10^3g X 10^6cm^3/1m^3 = 7.21 X 10^3 kg/m^3
not in scientific notation: 7.21g/1cm^3 X 1kg/1,000g X 1,000,000cm^3/1m^3 = 7,210 kg/m^3
(again notice how the grams (g) and the centimeters (cm) are canceled out, leaving only kilograms (kg) and meters (m))
*Finally make sure the numbers make sense. Since m^3 is a bigger volume than cm^3, the density in m^3 should be a larger number.


=
=

=Group 8
=

Determining Density
Co editor: Erika Paiva
Members: Shannon Degnan and Erika Paiva
  • density is the ratio of mass to volume an object has
  • density is an intensive property that depends only on the composition of a substance and how tightly packed the particles are
Density and Temperature

Erika Paiva

====Clarifying Important Terms

==


- Density is the ratio of an object's mass to its volume.

- Mass is the measure of the amount of matter that an object contains; the SI base unit for mass is the kilogram.

- Volume is a measure of the space occupied by a sample of matter.

- Shannon Degnan

===The Key Concept

=

- The volume of most substances increases as the temperature increases.

- The mass remains the same despite the volume change and the temperature.

- The density of a substance generally decreases as its temperature increases.


- Density changes with temperature because the volume changes with temperature.

- When the temperature increases, The volume, the space occupied by the matter is getting bigger/increases, but the mass is staying the same, so it is becoming less dense.

- Over a certain range of temperature, the volume of water increases as its temperature decreases. Ice, or solid water, floats because it is less dense than liquid water.




Calculating Density



mass- units g, kg, ect..

volume- units cm3, m3, ect...

Density- units g/cm3, ect..



Problem:

A block of aluminum has a volume of 15.0 mL and a mass of 40.5 g. What is the density?



1. Analyze:

list the known facts and the unknown.

Known

- mass= 40.5 g

- volume= 15.0 mL

Unknown

- density= ?



2. Calculate:

solve for the unknown

- substitute the known information and calculate.


D= Mass/volume = 40.5 g/ 15.0 mL = 2.70 g/mL


3. Evaluate:

does this make sense?




Using Density to Calculate Volume


- What is the volume of a pure silver coin that has a mass of 14 g? The density of a silver (AG) is 10.5 g/cm3.




1. Analyze:

List the knowns and the unknown.

Knowns

Mass of coin = 14g

Density of silver= 10.5 g/cm3


Unkown

Volume of coin= ? cm3.


- Solve this problem by using density as a conversion factor. You need to convert the mass of the coin into a corresponding volume. The density gives the following relationship between volume and mass.


1 cm3 Ag= 10.5 g Ag


- Notice that the known unit is in the denominator and the unknown unit is in the numerator.


=


2. Calculate:

Solve for the unknown

- Multiply the mass of the coin by the conversion factor to yield an answer in cm3.

14 g Ag X 1 cm3 Ag/ 10.5 g Ag= 1.3 cm3 Ag.



3. Evaluate:

Does this make sense?


=Density work sheet
=

1.

a. 1.98 g/mL

b. 2 g/mL

c. 1.26 g/ mL

d. 7.8 X 10 ^-3 g/mL

e. 7.95 g/ml

2.

a. 3.54 ml

b. 316.6 ml


The rest of the worksheet doesn’t pertain to the chapter, so don’t do the rest of the problems.