Chemistry+Chapter+1-3


 * Chemistry Chapters 1 and 3

Welcome to Mr. D's Chemistry Wiki, one of several created by Bishop Feehan High School's student body. I am Joe, and I will be your editor for this page. Here, we outline Chapters 1 and 3 from our chemistry textbook. We hope that whoever uses this wiki can find it informative and useful. -Joe Jennings, Editor.

Here are the Sections discussed and the people who worked on them. I type what I see, so if there are any mistakes, please come and see me. Co-Editor: Nick Achin Contributor: Emily Crawford. What is Chemistry:
 * 1: What is Chemistry?** Pages 7-11.
 * __Pages 7-8(Nick Achin)__**
 * Chemistry is the study of the composition of matter and the changes that matter under goes.
 * Matter is anything that has mass and occupies space.
 * Living and nonliving things are made of matter therefore chemistry affects all aspects of life.
 * Chemistry can explain how things happen in the world.
 * Areas of Study
 * The five traditional areas of chemistry are organic chemistry, inorganic chemistry, biochemistry, analytical chemistry, and physical chemistry.
 * Organic- study of all chemicals containing carbon with a few exceptions
 * Inorganic- study of all chemicals that do not contain carbon
 * Biochemistry- the study of the processes that take place inside organisms
 * Analytical- the study of the composition of matter
 * Physical- the study of the mechanism, the rate, and the energy transfer that occurs when matter undergoes change
 * Chemist often work in many areas of chemistry at once.

Contributor: Brittany Chlebek (pages 12-14)
 * 2: Chemistry Far and Wide** Pages 12-19

Materials: Energy: Medicine and Biotechnology: Biotechnology YouTube Video: [|Biotechnolgy]
 * Chemists design materials to fit specific needs
 * they usually use nature, to search for their inspiration
 * There are 2 ways to look at the world - macroscopic and microscopic views
 * macroscopic world - the world of objects that are large enough to see with the unaided eye
 * microscopic world - the world of objects that can be seen only under magnification
 * Energy is necessary to meet the needs of a modern society - used to heat buildings, manufacture goods, etc.
 * The demands of energy continue to increase, as the population of people on Earth increases
 * There are 2 ways t meet the demand for energy - conserve energy resources and find ways to produce more energy
 * Chemists play an essential role in finding ways to conserve energy, produce energy, and store energy
 * Conservation:
 * The easiest way to conserve energy is insulation - which acts as a barrier to heat flow from the inside to the outside of a house or from the outside to the inside of a freezer
 * SEAgel is the most exciting modern insulation - it is a foam made from seaweed
 * Production:
 * Fossil fuels are formed from the remains of ancient plants and animals
 * Fossil fuels are limited, however
 * Scientists are looking for ways to obtain fuel from plants
 * Storage:
 * Batteries use chemicals to store energy that will be released as electric current when the batteries are used
 * Batteries vary in size, levels of power, and time for operation
 * Cordless tools were first developed by NASA
 * Chemistry supplies the medicines, materials, and technology that doctors use to treat their patients.
 * The overall goal of biochemists is to understand the structure of matter found in the human body and the chemical changes that occur in cells
 * Medicines:
 * There are over 2,000 prescription drugs for many different treatments/conditions
 * OTC (over the counter) drugs can be sold without a prescription
 * Knowledge of the structure and function of target chemicals helps a chemist to design a safe and effective drug
 * Materials:
 * Chemists sometimes have to repair or replace body parts
 * Artificial hips & knees, plastic tubes for diseased arteries, etc.
 * Biotechnology:
 * Genes, segments of DNA, store the information that controls changes that take place in cells
 * Biotechnology applies science to the production of biological products or processes. When genes from humans are insterted into beacteria, the bacteria acts as factories because they produce chemicals of importance to humans
 * Scientists expect to use gene therapy to treat some diseases in the future

__ Agriculture __ The population of the world may be increasing; however the amount of land available to grow food is DECREASING! It is important to ensure that land used for agriculture is as productive as possible

Main idea: Chemists help to develop more productive crops and safer, more effective ways to produce them

Land Productivity- -can be measured through the amount of edible food that is grown on a given unit of land -decreased by poor soil quality, lack of water, weeds, plant diseases, and pests that eat crops

Chemists can save the day and protect our Earth! -They test the soil to check the chemical balance -The use biotechnology to develop plants that are more likely to resist the environment -They can conserve water EXAMPLE! A type of jellyfish as genes in it that cause it to glow!!!!!!! (prettttyyyy) If this gene is inserted into a potato plant, the potato will glow when it needs to be watered! (*Of course they remove that potato from the rest so we don't eat the weird jellyfish gene...) -Chemists are finding new chemicals to protect crops: a chemical designed to kill a pest used to also kill the helpful insects. Now, chemistry is used to treat specific problems!

__ The Environment __ A **pollutant** is a material found in air, water, or soil that is harmful to humans or other organisms Main idea: Chemists help to identify pollutants and prevent pollution

An example of a pollutant- lead -Romans used lead pipes for plumbing and storing their wine -Brain damage from this lead may have caused rulers to make bad decisions and the fall of the Roman Empire!!!! Chemists can identify pollutants like lead and help save lives!

__ The Universe __ Main idea: To study the universe, chemists gather data from afar and analyze matter that is brought back to Earth

-Chemists study the composition of stars and the Sun (this is how Pierre Janssen discovered Helium) -They analyze the materials brought back

Co-Editor: Ellen Mahoney Contributor: Lexie St. Jacques Contributor: Elena Berube (pgs. 20-21)
 * 3: Thinking Like A Scientist** Pages 20-27

__**1.3 Thinking Like a Scientist**__
Alchemy: -The study of //Chemistry// derived from the study of //alchemy//. -Before the study of chemistry began, there were alchemists who studied matter. -2 sides to alchemy: -Alchemists were the ones who developed the tools that are still used in chemistry today: beakers, flasks, tongs, funnels, and the mortar and pestal. -They did not provide logical explanations for the changes in matter, but that is how chemistry developed.
 * Practical Side: focused on techniques for working with metals, glass and dyes.
 * Mystical Side: focused on perfection. For example, because gold was considered a "perfect metal," they searched for ways to make other metals such as lead into gold.

http://www.youtube.com/watch?v=P7XX0DxUAHk
 * __Video: What Is Alchemy?__**

An Experimental Approach to Science -In the 1500s, alchemy started to die down and people began studying chemistry instead. -The Royal Society of London for the Promotion of Natural Knowledge was formed in Britain and it encouraged scientists to base their conclusions on the natural world on experimental evidence rather than philosophy. -Antoine-Lauren Lavoisier:
 * a chemist who helped to transform chemistry into the science of measurement that it is today.
 * also settled the debate questioning how chemicals burn by proving that oxygen was required for a material to burn
 * his wife helped his work by making drawings of his experiments and translating them from English
 * was targeted during the French Revolution and was beheaded in 1794

= **Collaboration and Communication** =


 * Collaboration is very important
 * When scientists collaborate, it increases the likelihood of a successful outcome

Ex: An industry may give a university funding for pure research in an area of interest to the industry. Scientists at the university get the equipment and the time required to do research. In exchange, the scientists provide ideas and expertise. The industry may profit from its investment by marketing applications based on the research.
 * Collaboration **
 * Scientists collaborate for different reasons
 * it's often necessary to bring together people from different disciplines
 * Each scientist brings (1) different knowledge and (2) a different approach to a problem
 * Talking with another scientist may provide insights
 * There may be a practical reason for collaboration
 * Not always a smooth process
 * Conflicts may arise about:
 * 1) Use of resources
 * 2) Amount of work
 * 3) Who is to receive credit
 * 4) When and what to publish
 * Likely work in the laboratory
 * Communication **
 * The way that scientists communicate has changed
 * Scientists used to exchange ideas via letters (Shocking, right?)
 * Formed societies to discuss the latest work of their members
 * Scientists used journals to keep up with new discoveries
 * Today many scientists work as a team
 * They communicate:
 * 1) Face to face
 * 2) By e-mail
 * 3) By phone
 * 4) At international conferences
 * Still publish their results in scientific journals -> most reliable source of information about new discoveries
 * Only published after being reviewed by experts
 * Reviewers may (1) find errors or (2) challenge the result
 * Good for science, because poorly funded experiments aren't usually published
 * Internet = major source of information (as is evident)
 * Anyone can access the information
 * But anyone can also post without having the information reviewed
 * You must consider the source when using the Internet
 * Same advice applies to newspapers, magazines, and television news
 * If the reporter specializes in science, the report may be more accurat
 * The Scientific Method **



 - logical, systematic approach to solution of scientific problem  - steps:  1. Observations  2. Testing Hypotheses  3. Developing Theories
 * science = "ordinary people doing ordinary things"
 * scientific method

 - similar to common sense  - observing is when your senses get information  - observation leads to questions  - hypothesis is a proposed explanation for an observation  - it has to be changed if the data doesn't fit the hypothesis  - experiments test hypotheses  *variables are factors that change in an experiment <span style="color: black; font-family: Arial,sans-serif; font-size: 10pt;"> * manipulated/independent variable is the variable that is changed during the experiment <span style="color: black; font-family: Arial,sans-serif; font-size: 10pt;"> * responding/dependent variable is the variable that is observed in the experiment <span style="color: black; font-family: Arial,sans-serif; font-size: 10pt;"> *during an experiment, if you keep other factors from changing, you can compare the changes in responding and manipulated variables <span style="color: black; font-family: Arial,sans-serif; font-size: 10pt;"> *in order for an experiment to be acceptable, the same results must always occur, no matter who performs the experiment or how many times it is performed, so scientists should publish their procedures along
 * **<span style="color: blue; font-family: Arial,sans-serif; font-size: 15pt;">Making Observations **
 * **<span style="color: blue; font-family: Arial,sans-serif; font-size: 15pt;">Testing Hypotheses **

<span style="color: black; font-family: Arial,sans-serif; font-size: 10pt;"> - a hypothesis can be turned into a theory after being tested repeatedly <span style="color: black; font-family: Arial,sans-serif; font-size: 10pt;"> - a theory is a well-tested explanation for a broad set of observations <span style="color: black; font-family: Arial,sans-serif; font-size: 10pt;"> - examples of theories: <span style="color: black; font-family: Arial,sans-serif; font-size: 10pt;"> *in chemistry, one theory about the fundamental structure of matter helps form mental pictures of matter <span style="color: black; font-family: Arial,sans-serif; font-size: 10pt;"> *another theory helps predict the behavior of matter <span style="color: black; font-family: Arial,sans-serif; font-size: 10pt;"> - theories can never be proved, there is always the possibility that a theory can be changed <span style="color: black; font-family: Arial,sans-serif; font-size: 10pt;"> - a scientific law is a concise statement which summarizes results of many observations and experiments <span style="color: black; font-family: Arial,sans-serif; font-size: 10pt;"> - laws can't explain the relationships they described, that requires a theory
 * **<span style="color: blue; font-family: Arial,sans-serif; font-size: 15pt;">Developing Theories **
 * **<span style="color: blue; font-family: Arial,sans-serif; font-size: 15pt;">Scientific Laws **
 * <span style="color: lime; font-family: Arial,sans-serif;">Examples: **
 * <span style="color: aqua; font-family: Arial,sans-serif; font-size: 10pt;">Scientific Method: **
 * <span style="color: black; font-family: Arial,sans-serif; font-size: 10pt;">You notice a flashlight is not working, which leads to the question, why doesn't the flashlight work? --->**Making Observations**
 * <span style="color: black; font-family: Arial,sans-serif; font-size: 10pt;">You guess the batteries to the flashlight are dead ---> **Hypothesis**
 * <span style="color: black; font-family: Arial,sans-serif; font-size: 10pt;">You put new batteries in the flashlight ---> **Testing Hypothesis**
 * <span style="color: black; font-family: Arial,sans-serif; font-size: 10pt;">The flashlight is still broken ---> **Testing Hypothesis (a new hypothesis is needed)**
 * <span style="color: black; font-family: Arial,sans-serif; font-size: 10pt;">You guess the light bulb is burned out ---> **Forming a new hypothesis**
 * <span style="color: black; font-family: Arial,sans-serif; font-size: 10pt;">You change the bulb ---> **Testing Hypothesis**
 * <span style="color: aqua; font-family: Arial,sans-serif;">Scientific Laws: **
 * <span style="color: black; font-family: Arial,sans-serif; font-size: 10pt;">relationship between volume of gas and its temperature, the volume increases as the temperature increases (Scientific Law, it can't explain the relationship)

Co-Editor: Kyle Mahoney Contributor: Lauren Berube **Problem Solving in Chemistry**
 * 4 Problem Solving in Chemistry** Pages 28-32

‍Skills Used in Solving Problems



 * Problem solving skills are useful in everyday life.

- There are many tools that can be helpful in the process of problem solving. There are data tables, graphs, and many other types of visuals that can be very useful.

- Similar skills are used in solving Chemistry word problems as problem solving in everyday life, like shopping or cooking.

//__Effective Problem Solving always involves developing a plan and then implementing that plan.__//

‍Solving Numeric Problems
There is a three- step problem solving strategy for solving problems, especially math problems, in Chemistry. The steps in this strategy are analyze, calculate, and evaluate.

<span style="color: #008000; font-family: Arial,Helvetica,sans-serif; font-size: 110%;">Analyze: - The part of analyzing is to figure out where you are starting from, or identify what parts of the problem are already known and what is unknown. - Then, you must make a plan as to how you will arrive at the answer. Drawing a diagram or a table may be helpful for this step.

Calculate: - After you have finished planning, you should use the plan you have come up with to start doing the calculations. - This step may require converting measurements or rearranging equations.

Evaluate: - Lastly, after you have calculated your answer, you should look back and see if it makes sense. - Check to mak sure the answer has correct labels and correct number of significant figures. <span style="color: #ff0000; font-family: Arial,Helvetica,sans-serif; font-size: 200%;">Solving Conceptual Problems - The steps for solving a conceptual problem are analyze and solve.
 * The three step problem solving approach is modified for conceptual problems.
 * Do the problem on page 30 since these problems need a diagram usually.**

= **3.1 Measurements and Their Uncertainty** Pages 63-72 = Coeditor: Hannah Mullen (69-72) Contributor:Sami Massoud (63-65) Contributor:Melanie Brondyk (66-68)

** Using and Expressing Measurements **
A **measurement** is a quantity that has both a number and a unit.

-Measurements are used in everyday life, such as your height or the speed you drive at.

//__Measurements are fundamental to the experimental scientists. For that reason, it is important to be able to make measurements and to decide whether a measurement is correct.__//

-The units in the International System of Measurements are typically used by scientists.

-Used to write very large or very small numbers so that they are easier to work with. -When using scientific notaion, a given number is written as the product of two numbers: a coefficient and 10 raised to a power.
 * Scientific notation**

Here is an example of using scientific notation:

200,000,000,000 = 2 x 10^11 2 is the coefficient in this number. The decimal moves 11 places to the left, making the exponent 11.

Here is a link to a video explaining scientific notation: []

//For more practice on scientific notation, see page R56 of Appendix C in the chem textbook.//


 * Accuracy, Precision, and Measure **


 * Accuracy and Precision **

**Accuracy** is a measurement of how close a measurement comes to the actual or true value of whatever is measured.
 * Precision ** is a measure of how close a series of measurements are to one another.

-To evaluate the accuracy of a measurement, the measured value must be compared to the correct value.

-To evaluate the accuracy of a measurement, the measured value must be compared to the correct value.

The dart that landed on the bullseye is an example of accuracy.

This dart missed the bullseye, representing poor accuracy.

-To evaluate the precision of a measurement, you must compare the values of two or more repeated measurements.

These darts represent good precision because all of the darts landed near each other

These darts represent poor precision because they did not land near each other.

** Determining Error **

**Error is the difference between the accepted value and the experimental value of a measurement. It can be positive or negative.** **Accepted Value** is the correct value based on reliable references. **Experimental value** is the value measured in the lab.

//Error = experimental value - accepted value//


 * Percent error** is the absolute value of the error divided by the accepted value, multipied by 100%.

This video gives examples of how to calculate error and percent error. [] (Melanie Brondyk)
 * Pg. 66-68**

Significant Figures in Measurements
-With a scale, it is possible to estimate the weight of an object to the nearest hundredth of a pound -Make sure to not the position of the pointer between calibration marks when doing so.

Example:
A weight that is between 2.4 lb and 2.5 lb can equal 2.46 by estimating between the two calibration marks. -2 and 4 are certain and the 6 is uncertain and estimated.

Significant Figures:
Include all of the digits that are known, plus a last digit that is estimated. In the example shown, 2.46 is the significant digits. -Calculated answers help determine what the number of significant figures will be used in the calculations.

Rules to help determine if the digit is significant:
1.) Every other number but zero is significant. If the value ends with a zero it is insignificant. 2.) Zeros that are in between two significant numbers are significant. 3.) The zeros that are in front of the left of the decimal place are insignificant. (ex. 0.0071, the zero that is before the decimal place is insignificant, but the two zeros before the 7 and 1 are significant.) A tool to help use placeholders is by using scientific notation. 4.) Zeros at the end of a number of to the right of a decimal place before a value are always significant. 5.) To make zeros significant in the number, use scientific notation. They show the magnitude of the number. 6.) Exact quantities do not affect the process of rounding an answer to the correct number of significant figures.

Significant Figures in Calculations
- A calculated value must be rounded.

Rounding:
- First, decide how many significant figures there should be in the answer. (Depends on the given measurements and the process to receive the answer) - Next, round to the digits starting from the left to the right. If the digit to the right is less than 5, it is dropped and the value stays the same, but if it is equal to or more than 5, the value of the place to the left of that number is increased by 1.

Significant Figures in Calculations (Rounding example)
-If the digit following the last significant digit is less than 5, you do not round up. -If the digit following the last significant digit is 5 or more, you round up. Ex: 5.63 2 (where 3 is the last significant digit) because 2 is less than 5, you do not round up. The rounded answer is 5.63. 5.63 8 (where 3 is the last significant digit) because 8 is greater than 5, you do round up. The rounded answer is 5.64.

-Scientific Notation can be used when rounding. Ex: 314.72 1 meters (when 2 is the last significant digit) because 1 is less than 5, you do not round up. The rounded answer is 314.72 meters. This is 3.1472 X 10^2 (10 to the second power) meters in Scientific Notation.

Addition and Subtraction
-When adding or subtracting 2 calculations, the answer should be rounded to the least number of decimal places of the two. Ex: 20.54 meters + 13.2 meters.The answer to this is 33.74 meters. because the lowest number of decimal places of the two added calculations is one, the answer must be rounded to one decimal place. 4 is less than 5, so the answer rounds to 33.7 meters.

Multiplication and Division
-When rounding, the decimal place does not matter. -The answer must be rounded to the same number of significant figures as those of the multiplied/divided number with the least number of significant figures. Ex: 7.55 meters x 0.34 meters. The answer to this is 2.567 meters squared. Because 0.34 meters only has two significant figures, that is the amount the answer should be rounded to. 6 is greater than 5, so 2.567 rounds to 2.6 meters squared. Thus the answer has two significant figures.

Co-Editor: John Bailey Pages 76-79 Contributor: Sean Lydon Pages 73-75 = ** __3.2 The International System of Units__ ** = = **Measuring with SI Units** = The standards of measurement used in science are those of the metric system. The metric system is simple and easy to use because it based on multiples of 10, making it easy to convert from one unit to another. It was established in France in 1795. The International System of Units, or SI is a revised version of the metric system and was adopted by international agreement in 1960. All measured quantities can be recorded in SI units, but non-SI units﻿ are sometimes used for convenience.
 * 6 The International System of Units** Pages 73-79
 * Key Concept: The 5 SI base Units commonly used by chemists are the meter, the kilogram, the kelvin, the second, and the mole. **
 * SI Base Units **
 * Quantity || SI Base Unit || Symbol ||
 * Length || meter || m ||
 * Mass || kilogram || kg ||
 * Temperature || kelvin || K ||
 * Time || second || s ||
 * Amount of substance || mole || mol ||
 * Luminous intensity || candela || cd ||
 * Electric Current || ampere || A ||

= ** Units and Quantities﻿ ** ﻿﻿= Before you make a measurement, you must know the units that correspond to the quantity you are trying to measure. = **Units of Length** = In SI, the basic unit of length is the meter. However, for very large and very small lengths, it might be easier to use a unit of length with a prefix. For smaller units you might use the millimeter, which is about the length of a hyphen (-). For larger units you might use the kilometer, which measures about the length of 5 city blocks. = **Units of V﻿olume** = The space occupied by any sample of matter is called its volume. Volume = length x width x height. The SI unit of volume is the cubic meter (m to the 3rd power). The liter is a more convenient unit of volume for everyday use. It is the volume of a cube that is 10 centimeters along each edge, which is 1000 cm cubed or 1 cubic decimeter (dm to the 3rd power). Because 1 L is equal 1000 milliliters (mL) and also 1000 cm cubed, 1 mL and 1 cm cubed are the same volume and can be used interchangeably. Many devices are used to measure liquid volumes, including graduated cylinders, pipets, burets, volumetric flasks, and syringes. The volume of any gas, solid, or liquid will change with temperature, with the change being greater with gases. As a result, accurate volume-measuring devices are calibrated at a given temperature, usually 20 degrees Celsius (room temperature). Refer to pages 73-75 in the textbook for more information on each section. Co-Editor: Maddie Harmon Contributor: Marie Wachter
 * Commonly Used Metric Prefixes**
 * Prefix || Meaning || Factor ||
 * mega (M) || 1 million times bigger || 10 to the 6th power ||
 * kilo (k) || 1000 times bigger || 10 to the 3rd power ||
 * deci (d) || 10 times smaller || 10 to the -1st power ||
 * centi (c) || 100 times smaller || 10 to the -2nd power ||
 * milli (m) || 1000 times smaller || 10 to the -3rd power ||
 * micro (//u//) || 1 million times smaller || 10 to the -6th power ||
 * nano (n) || 1000 million times smaller || 10 to the -9th power ||
 * pico (p) || 1 trillion times smaller || 10 to the -12th power ||
 * Key Concept: Common metric units of length include the centimeter, meter, and kilometer.**
 * Metric Units of Length**
 * Unit || Relationship || Example ||
 * kilometer (km) || 1000 m || about 5 city blocks ||
 * meter (m) || base unit || height of doorknob from floor ||
 * decimeter (dm) || .1 m || diameter of large orange ||
 * centimeter (cm) || .01 m || width of shirt button ||
 * millimeter (mm) || .001 m || thickness of dime ||
 * micrometer (//u//m) || .000001 m || diameter of bacterial cell ||
 * nanometer (nm) || .000000001 m || thickness of RNA molecule ||
 * Key Concept: Common metric units of volume include the liter, millileter, cubic centimeter, and microliter.**
 * Metric Units of Volume**
 * Unit || Relationship || Example ||
 * Liter (L) || base unit || quart of milk ||
 * Milliliter (mL) || .001 L || 20 drops of water ||
 * Cubic centimeter (cm cubed) || .001 L || cube of sugar ||
 * Microliter (//u//L) || .000001 L || crystal of table salt ||
 * ****#7 Conversion Problems** Pages 80-87
 * ****#7 Conversion Problems** Pages 80-87
 * ****#7 Conversion Problems** Pages 80-87

Co-Editor: Korey Dufault Pages 88-91 Contributor: Kyle St. Pierre Pages 91-93
 * 8 Density** Pages 88-93

=<span style="color: #000080; font-family: Arial,Helvetica,sans-serif; font-size: 270%;">**Density** =

Determining Density:


 * ** ﻿Density ** is the ratio of the mass of an object to its volume.
 * **Density =** ﻿﻿mass/volume



Equations


 * Example:** A 10.0cm3 piece of lead, for example has a mass of 114 g. What, then, is the density of lead? You can calculate it by substituting the mass and volume into the equation above.


 * Answer:** 114 g/10.0cm^3= 11.4 g/cm^3. Note that when mass is measured in grams, and volume in cubic centimeters, density has units of grams per cubic centimeter (g/cm^3).
 * Density is an intensive property that depends only on the composition of a substance, not on the size of the sample.
 * Figure 3.13 on page 89 compares the density of three substances. The volumes vary because the substances have different densities.
 * With a mixture, density can vary because the composition of a mixture can vary.



Density and Temperature:
 * Experiments have shown that the volume of most substances increases as the temperature increases.
 * Mass stays the same despite the temperature and volume changes.
 * If the volume changes with temperature (while the mass remains constant), then the density must also change with temperature.
 * The density of a substance generally decreases as its temperature increases.



A copper penny has a mass of 3.1g and a volume of 0.35cm^3. What is the density of copper? || mass = 3.1g density = ?g/cm^3 volume = 0.35 cm^3 Use the known values and the following definition of chemsity. Density = mass/volume || The equation is already set up to solve for the unknown. Substitute the known values for the mass and volume, and calculate the density. Density = mass/volume = 3.1g/0.35cm^3 = 8.8571g/cm^3 =8.9g/cm^3 (rounded to two significant figures) || A piece of copper with a volume of about 0.3cm^3 of copper had a mass of about 3 grams. Thus, about three times that the volume of copper, 1cm^3, should have a mass three times larger, about 9 grams. This estimate agrees with the calculated result. ||
 * ~ Sample Problem ||
 * Calculating Density
 * Analyze // List the knowns and unknown //
 * Known Unknown **
 * Calculate // Solve for the unknown //
 * Evaluate // Does the result make sense? //

What is the volume of a pure silver coin that has a mass of 14g? The density of silver (Ag) is 10.5g/cm^3 || mass of coin = 14g volume of coin = ?cm^3 Density of silver = 10.5g/cm^3 You can solve the problem by using the 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 the volume and mass. 1cm^3 Ag = 10.5g Ag Based on this relationship, you can write the following conversion factor. 1cm^3 Ag / 10.5g Ag Notice that the unknown unit is the denominator and the unknown unit is in the numerator || Multiply the mass of the coin by the conversion factor to yield an answer in cm^3 14g Ag X 1cm^3 Ag / 10.5g Ag = 1.3cm^3 Ag || Because the mass of 10.5g of silver has a volume of 1cm^3, it makes sense that 14.0g of silver should have a volume slightly larger than 1cm^3. The answer has two significant figures because the given mass has two significant figures ||
 * ~ Sample Problem 2 ||
 * Using Density to Calculate Volume
 * Analyze //List the known and the unknown//
 * Known Unknown**
 * Calculate // Solve for the unknown //
 * Evaluate // Does the result make sense? //

Here is a video to help practice:

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[|More Practice Worksheets]

**Analytical Chemist:**


 * Analytical Chemist focus on making quantitive measurements.
 * Spend time making measurements and calculations to solve laboratory and math based research problems.
 * This job requires creativity.
 * Many new fields are now hiring analytical chemists.
 * This job requires extensive education, including advanced chemical training, molecular biology, and computer operation.