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= = =MOLE THEORY = =Editor: Olivia Hitchcock = **1. The Mole: A Measure of Matter pp. 287-296 ** **Co-Editor: Meaghan Demers-Peel** **Group:** An Nguyen Jack LaBelle Robbie Achin Tyler Robertson Victoria Cleveland Tyler Robertson

**__Measuring Matter 287-289 (An Nguyen)__ **
 * -Chemistry involves quantitative measures
 *  **-** **Measurements can be made by**
 *  **-** ** //__Count__// ** **(5 pencils)**
 * <span style="font-family: Arial,Helvetica,sans-serif;"> **-** ** //__Mass__// ** **(37 kilograms)** [[image:apples.jpg width="135" height="190" align="right"]]
 * <span style="font-family: Arial,Helvetica,sans-serif;"> **-** ** __//Volume//__ ** **(2.2 liters)**
 * <span style="font-family: Arial,Helvetica,sans-serif;">-Some units used to measure indicate a specific number of items
 * <span style="font-family: Arial,Helvetica,sans-serif;">-A pair is 2
 * <span style="font-family: Arial,Helvetica,sans-serif;">-A dozen is 12
 * <span style="font-family: Arial,Helvetica,sans-serif;">-A gross is 144
 * <span style="font-family: Arial,Helvetica,sans-serif;">-One type of item can be measured three different ways. For example:
 * <span style="font-family: Arial,Helvetica,sans-serif;">-Apples can be sold by the count (3 apples for $2.40)
 * <span style="font-family: Arial,Helvetica,sans-serif;">-Apples can be sold by mass ($2.79 for 1 kilogram)
 * <span style="font-family: Arial,Helvetica,sans-serif;">-Apples can be sold by volume ($12 for a bushel)
 * <span style="font-family: Arial,Helvetica,sans-serif;">-Each of the above measurements applies to one dozen, 2.0 kg, or 0.2 of apples
 * <span style="font-family: Arial,Helvetica,sans-serif;"> -You can convert among units of count, mass, and volume using their relationships and dimensional analysi s
 * <span style="background-color: #ffff00; font-family: Tahoma,Geneva,sans-serif; font-size: 120%;">[|Online Converter]

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 * <span style="font-family: Arial,Helvetica,sans-serif;">Problem 10.1 explained by Jordan Bellucci **

<span style="color: #ff0000; font-family: Tahoma,Geneva,sans-serif; font-size: 130%;">__**What Is A Mole? 290 (Robbie Achin)**__


 * <span style="font-family: Arial,Helvetica,sans-serif;">-Chemists use moles for a specified number of particles
 * <span style="font-family: Arial,Helvetica,sans-serif;">-A __//** mole **//__ of a substance is 6.02 x 10^23 representative particles of that substance and is the SI unit for measuring the amount of a substance
 * <span style="font-family: Arial,Helvetica,sans-serif;">-6.02 x 10^23 is called **__// Avogadro’s Number //__**
 * <span style="font-family: Arial,Helvetica,sans-serif;">The number was named after Italian scientist Amedeo Avogadro di Quaregna because he helped clarify the difference between atoms and molecules
 * <span style="font-family: Arial,Helvetica,sans-serif;">-__//** Representative particle **//__ refers to the species present in a substance
 * <span style="font-family: Arial,Helvetica,sans-serif;">The representative particle in most elements is the atom itself
 * <span style="font-family: Arial,Helvetica,sans-serif;">-Elements that exist as diatomic molecules have the molecule as the representative particle
 * <span style="font-family: Arial,Helvetica,sans-serif;">-Moles = representative particle X 1 mole/6.02 X 10^23

**<span style="color: #ff0000; font-family: Tahoma,Geneva,sans-serif;">__Converting Moles to Number of Particles 291-293 (Jack LaBelle)__ **


 * -To determine how many atoms are in a mole of a compound, you need to know how many atoms are in a representative particle of the compound.


 * -For example: carbon dioxide(CO2) consists of one carbon atom and two oxygen atoms.


 * - Since a mole of CO2 has Avogadro’s number of CO2 molecules, it consists of three times Avogadro’s number of atoms because of the three atoms


 * in CO2.


 * -The formula for the number of atoms in a mole of a compound is:


 * - representative particles = moles x (6.02x10^23 representative particles) / 1 mole


 * -after you get the representative particles, you have to multiply the number by the number of atoms in each molecule
 * -Avogadro’s number is so big that if there was Avogadro’s number of animal moles which are about 15 cm long, then it would stretch from Earth to the nearest star more than two million times.

media type="youtube" key="3HOZPb9Idak" height="344" width="425" **<span style="font-family: Tahoma,Geneva,sans-serif;">Problem 10.2 explained by Jordan Bellucci **

<span style="font-family: Tahoma,Geneva,sans-serif;">media type="youtube" key="BGYJuCIIAF8" height="344" width="425" **<span style="font-family: Tahoma,Geneva,sans-serif;">Problem 10.3 explained by Jordan Bellucci **

<span style="background-color: #ffffff; color: #000000; font-family: Arial,Helvetica,sans-serif; font-size: 120%;">** __The Mass of a Mole of an Element 293-294 (Tyler Robertson)__ **


 * -table 10.2 shows that the average carbon atom with and atomic mass of 12 amu is 12 times heavier than an average hydrogen atom with an atomic mass of 1.0 amu


 * -any number of carbon atoms is 12 times heavier than the same number of hydrogen atom [[image:scan0004.jpg width="584" height="354" align="right"]] s; the mass ratio of 12 carbon atoms to 1 hydrogen atoms remains the same no matter what unit is used to express the masses


 * -chemists have converted the relative scale of massws of the elements in amu to a relative scale of masses in grams


 * -The atomic mass of an element expressed in grams is the mass of a mole of the element


 * Ex.- carbon's molar mass is 12.0 grams and atomic hydrogen's molar mass is 1.0


 * -the mass of an element is its molar mass


 * -the molar masses of any two elements must contain the same number of atoms


 * -the molar mass of any element contains 1 mol or 6.02 X <span style="font-family: 'Calibri','sans-serif'; font-size: 11pt; line-height: 115%;">1023 atoms of that element

<span style="color: #ff0300; font-family: Tahoma,Geneva,sans-serif; font-size: 130%;">__**<span style="font-family: Tahoma,Geneva,sans-serif;">The Mass of a Mole in a Compound 295-296 (Victoria Cleveland) **__


 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">-To find the mass of a mole of a compound, you must know the formula of the compound.
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">Ex: The formula of sulfur trioxide is SO3, so a molecule of SO3 is made of one sulfur and three oxygen atoms.
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">-You can find the mass of a molecule by adding the atomic masses of the atoms making up the molecules.
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">Ex: From the periodic table the atomic mass of sulfur is 32.1 amu. The mass of three atoms of oxygen is 3 times 16.0 amu (the mass of one oxygen atom) = 48 amu. So the molecular mass of SO3 is 32.1 amu + 48.0 amu = 80.1 amu.
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">-To find the molar mass you then substitute the unit grams for atomic mass units. The molar mass of a compound is the mass in grams of 1 mol of that compound.
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">Ex: 1 mol of SO3 has a mass of 80.1 g. This is the mass of 6.02 x 1023 molecules of SO3.
 * <span style="font-family: Tahoma,Geneva,sans-serif;">**<span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">-To find the molar mass of a compound, find the number of grams of each element in one mole of the compound. Then add the masses of the elements in that compound. **

<span style="background-color: #ffffff; font-family: Tahoma,Geneva,sans-serif; font-size: 130%;">[|Practice Worksheets]
media type="youtube" key="XvYCuB9JhVs" height="344" width="425" <span style="font-family: Arial,Helvetica,sans-serif;">**<span style="font-family: Arial,Helvetica,sans-serif;">Problem 10.4 explained by Jordan Bellucci **

<span style="color: #0000ff; font-family: Arial,Helvetica,sans-serif; font-size: 150%;">2. Mole Relationships pp. 297-304
<span style="font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">**<span style="font-family: Arial,Helvetica,sans-serif;">Co-editor: Sarah Fishbach ** <span style="font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">**<span style="font-family: Tahoma,Geneva,sans-serif;">Group: **<span style="font-family: Tahoma,Geneva,sans-serif;">Matt Creeden <span style="font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">Mike Bickford <span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">Chris Adams <span style="font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">Kayle Galleta <span style="font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">Nate Patch Alex Boucher

==<span style="color: #ff0000; font-family: Tahoma,Geneva,sans-serif; font-size: 120%; font-weight: normal;">__**<span style="font-family: Arial,Helvetica,sans-serif;">The Mole-Mass Relationship 297-299 (Matt Creeden) **__ ==

<span style="font-family: Arial,Helvetica,sans-serif;">The **molar mass** of any substance is the mass in grams of one mole of that substance

<span style="font-family: Arial,Helvetica,sans-serif;">Use the molar mass of an element or compound to convert between the mass of a substance and the moles of a substance. The conversion factor is 1mol=molar mass

<span style="font-family: Arial,Helvetica,sans-serif;">mass(grams)=#of moles X mass(g)/1 mole <span style="font-family: Arial,Helvetica,sans-serif;">ex. mass of NaCl=3.00mol X 58.5g/1mol=176g

<span style="font-family: Arial,Helvetica,sans-serif;">THE SAME FORMULA CAN BE USED IN REVERSE

<span style="font-family: Arial,Helvetica,sans-serif;">moles=mass(grams) X 1mole/mass(grams) <span style="font-family: Arial,Helvetica,sans-serif;">ex. moles of Na2SO4= 10.0g X 1mol/142.1g=7.04X10^-2 mol

<span style="font-family: Tahoma,Geneva,sans-serif;">[|This Website May Be Helpfull]

<span style="font-family: Tahoma,Geneva,sans-serif;">media type="youtube" key="NGhG3klONTg" height="344" width="425" <span style="font-family: Tahoma,Geneva,sans-serif;">**Problem 10.5 explained by Jordan Bellucci**

<span style="color: #000000; font-family: Tahoma,Geneva,sans-serif; font-size: 16pt;">media type="youtube" key="T1ucDlCxnCc" height="344" width="425" <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; font-size: 16pt; letter-spacing: 0px;">** Problem 10.6 explained by Kerrin Gallagher **

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 150%;">** __The Mole-Volume Relationship 300-302 (Mike Bickford)__ **

· <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Volumes of one mole of different solid and liquid substances aren't the same o <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">ex) Volumes of one mole of glucose and one mole of paradichlorobenzene are much larger than the volume of one mole of water · <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Volumes of moles of gases (measured under the same physical conditions) are more predictable  o **<span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Avogadro's hypothesis: **<span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">states that equal volumes of gases at the same temperature and pressure contain equal numbers of particles  o <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Particles that make up different gases are different sizes  o <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Particles in gases are far apart and therefore a collection of relatively large particles doesn't require much more space than the same number of relatively small particles § <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Volume of a gas varies with a change in temperature and/or pressure o <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Volume of a gas is usually measured at a **standard temperature and pressure (STP)** § <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Temperature of 0oC and pressure of 101.3 kPa, or 1 atmosphere (atm) § <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">At **STP**, 1 mol or 6.02 x 1023 representative particles, of any gas occupies a volume of 22.4 L · <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">22.4 L is known as the **molar volume** of a gas · <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Calculating Volume at **STP** o **<span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Molar Volume **<span style="font-family: 'Times New Roman','serif'; font-size: 12pt;"> is used to convert a known number of moles of the gas at **STP** o <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Use the conversion factor: <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">**volume of gas = moles of gas x 22.4L/1 mol** § **<span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">ex) **<span style="font-family: 'Times New Roman','serif'; font-size: 12pt;"> volume of O2 = 0.375 mol x 22.4 L/1 mol = 8.40 L o <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">To calculate the number of moles of gas using the volume of a gas at **STP**, use the same relationship: 22.4 L = 1 mol  o **<span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">ex) **<span style="font-family: 'Times New Roman','serif'; font-size: 12pt;"> To calculate the number of moles of hydrogen in an experiment in which you collect 0.200 liter of hydrogen gas at **STP**: <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">moles = 0.200 L x 1 mol H2/22.4 L = 8.93 x 10-3 mol H2 · <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Calculating Molar Mass from Density o <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Different gases have different densities, usually measured in grams per liter (g/L) and at a specific temperature o <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">The density of a gas at **STP** can be used to calculate the molar mass of the ga <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">[|Check here for futher information about calculating the density and molar mass of gases] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 80%; letter-spacing: 0px;">**Info by John G.**
 * <span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">**molar mass = density at STP x molar volume at STP**
 * grams/mole = grams/L = 22.4 L/1 mole

<span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">media type="youtube" key="dGE3WMIBl78" height="344" width="425" <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">**Problem 10.7 explained by Kerrin Gallagher**

<span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">media type="youtube" key="-fH5eHg4gXQ" height="344" width="425" <span style="font-family: Arial,Helvetica,sans-serif; font-size: 140%; letter-spacing: 0px;">**Problem 10.8 explained by Kerrin Gallagher**

<span style="color: #ff0000; font-family: Tahoma,Geneva,sans-serif; font-size: 140%; letter-spacing: 0px;">** __The MOLE-VOLUME Relationship (again) 300-302 (Chris Adams)__ **
 * <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">Avogadro's Hypothesis- equal volumes of gases at the same pressure and temperature contain equal numbers of particles
 * <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">The particles that make up differnt gases are not the same size
 * <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">Particles in gases are far apart and therefore a collection of relatively large particles doesn't require much more space than the same number of relatively small particles
 * <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">Standard Temperature and Pressure (STP)- a temperature of 0 degrees celsius, and a constant pressure of 1 atmosphere.
 * <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">at STP, 1 mol (6,02x10^23 representative particles) of any gas occupies 22.4L
 * <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">22.4L is the molar volume
 * <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">Calculating the volume at STP- volume of gas= moles of gas x (22.4L/1 mol)
 * <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">Calculating the moles at STP- moles= volume of gas x (1 mol/22.4L)
 * <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">Different gases have different densities
 * <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">Density of a gas is measured at grams per liter
 * <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">Calculating molar mass from density- molar mass= density at STPxmolar volume at STP,
 * __ Nathan Patch The Mole Road Map pg. 303 __**
 * __ Nathan Patch The Mole Road Map pg. 303 __**

<span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">**__[|The Mole Road Map]__** A mole can be in terms of particles, mass, and volume of gases. This figure above summarizes these relation ships and illustrates the importance of the mole. The mole is the center of the chemical calculations. To convert 2 units you must use the mole. The form of conversion depends on what you know and what you want to know. gram/mole=(grams/L)x(22.4L/1 mol)

<span style="color: #ff0000; font-family: Tahoma,Geneva,sans-serif; font-size: 140%; letter-spacing: 0px;">** __MOLE-VOLUME Relationship and Molar Mass- Basics, resources, and practice. Alex Boucher.__ **

<span style="color: #ff0000; font-family: Tahoma,Geneva,sans-serif; font-size: 140%; letter-spacing: 0px;">** Molar mass **** and Mole calculation basics. ** <span style="color: #ff0000; font-family: Tahoma,Geneva,sans-serif; font-size: 140%; letter-spacing: 0px;"> media type="youtube" key="mDM_2BR5LnU" height="344" width="425"

** Molar Volume Basics **
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All credit to videos goes to their owners. ~

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Molar Conversion Basics

<span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 120%;">Molar Mass Calculator!

<span style="color: #0000ff; font-family: Arial,Helvetica,sans-serif; font-size: 150%; letter-spacing: 0px;">3. % Composition & Formulars pp. 305-312
<span style="font-family: Tahoma,Geneva,sans-serif; font-size: 90%; font-weight: normal; letter-spacing: 0px;">**Co Editor- Maxwell Dunbar** <span style="font-family: Tahoma,Geneva,sans-serif; font-size: 90%; font-weight: normal; letter-spacing: 0px;">**Group**: Chad Benoit (sample math problems) <span style="font-family: Tahoma,Geneva,sans-serif; font-size: 90%; font-weight: normal; letter-spacing: 0px;">Caroline Steiner <span style="font-family: Tahoma,Geneva,sans-serif; font-size: 90%; font-weight: normal; letter-spacing: 0px;">Olivia Cortellini <span style="font-family: Tahoma,Geneva,sans-serif; font-size: 90%; font-weight: normal; letter-spacing: 0px;">Emily Tormey <span style="font-family: Tahoma,Geneva,sans-serif; font-size: 90%; letter-spacing: 0px;">Brendan O'Neil

==<span style="color: #ff0000; font-family: Tahoma,Geneva,sans-serif; font-size: 120%;">__<span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">The Percent Composition of a Compound 305-308 (Caroline Steiner) __ == <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">**Percent Compositio****n**- the percent by mass of each element in a compound <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">-Consists of a percent value for each different element in the compound <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">*The percent by mass of an element in a compound is the number of grams of the element divided by the mass in grams of the compound multiplied by 100% <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">Percent Composition from Mass Data: <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">-Use analytical procedures to determine the relative masses of each element in the compound and calculate the percent composition. <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">Percent Composition from the Chemical Formula: <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">-You can calculate the percent composition if the chemical formula is known <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">-Subscripts are used to calculate the mass of each element in a mole of that compound <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">-Sum of these masses is the molar mass. <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">-Using the individual masses of the elements and the molar masses you can calculate the percent by mass of each element in one mole of the compound. <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">-Divide the mass of each element by the molar mass and multiply the result by 100%.

<span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">Mass of element in 1 mol compound <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">% mass= - X 100% <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">Molar mass of a compound

<span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">Percent Composition as a Conversion Factor <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">-Use percent composition to calculate the number of grams in a specific mass of a compound <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">-Multiply the mass of the compound by a conversion factor based on the percent composition of the element.

media type="youtube" key="xEZq7B-4kJw" height="344" width="425"
 * Problem 10.9 explained by Kerrin Gallagher**

//<span style="color: #008000; font-family: Arial,Helvetica,sans-serif; font-style: normal; letter-spacing: 0px;">**When a 13.60g sample of a compound containing only magnesium and oxygen is decomposed, 5.40g of oxygen is obtained. What is the percent composition of this compound?** // <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">1) //<span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">what is known? // <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;"> - mass of the compound (13.60 g), mass of oxygen (5.40 g) //<span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">what needs to be found? // <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">- mass of magnesium, percent magnesium (Mg), percent oxygen(O) <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">2) //<span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">Solve for the unknowns: // <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">mass of Mg = 13.60 g - 5.40 g <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">mass of Mg = 8.20 g <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">% Mg= (mass of Mg)/(mass of compound) x 100% <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">% Mg= (8.20 g)/(13.60 g) x 100% **<span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">% Mg= 60.3% ** <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">% O= (mass of O)/(mass of compound) x 100% <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">% O= (5.40 g)/(13.60 g) x 100% **<span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">%O= 39.7% ** <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">3) //<span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">Check your answer // <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">: 60.3% + 39.7% = 100% <span style="color: #000000; font-family: arial,helvetica,sans-serif; font-size: 24px; letter-spacing: 0px; line-height: 35px;">** [|Practice Problems and Further Explanation] **
 * sample problem:** //<span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">**how to calculate % composition from mass data (Chad Benoit)** //

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 * Problem 10.10 explained by Kerrin Gallagher**

<span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">1) //<span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">what is known? - // <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">mass of C in 1 mol C₃H₈ (36.0 g), mass of H in 1 mol C₃H₈ (8.0g), molar mass of C₃H₈ (44.0 g/mol) //<span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">what needs to be found? - // <span style="font-family: Arial,Helvetica,sans-serif; font-weight: normal; letter-spacing: 0px;">percent carbon (C), percent hydrogen (H) <span style="font-family: Arial,Helvetica,sans-serif; font-weight: normal; letter-spacing: 0px;">2) //Solve for the unknowns:// <span style="font-family: Arial,Helvetica,sans-serif; font-weight: normal; letter-spacing: 0px;">% C= (mass of C)/(mass of propane) x 100% <span style="font-family: Arial,Helvetica,sans-serif; font-weight: normal; letter-spacing: 0px;">% C= (36.0 g)/(44.0g) x 100% <span style="font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">**% C= 81.8%** <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">% H= (mass of H)/(mass of propane) <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">% H= (8.0 g)/(44.0 g) x 100% **% H = 18%** 3) //Check your answer:// <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">The answers 18% and 81.8% add up to 100% when expressed to 2 significant figures. <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">18% + 82% = 100%
 * sample problem//://** **//how to calculate % composition from a formula (Chad Benoit)//**
 * //<span style="color: #05b305; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">Propane (C₃H₈), the fuel commonly used in gas grills, is one of the compounds obtained from petroleum. Calculate the percent composition of propane. //**

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<span style="font-family: Helvetica,Geneva,sans-serif; line-height: normal;">2) //Solve for the unknowns//: <span style="font-family: Tahoma,Geneva,sans-serif; line-height: 17px;">Percent is equal to the # of parts in 100 parts, so using % composition it is known that... ======

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<span style="font-family: Helvetica,Geneva,sans-serif; line-height: normal;">3) //Check your answer//: <span style="font-family: Tahoma,Geneva,sans-serif; line-height: 17px;">The answers should both add up to the mass of the substance (in this case to 2 sig figs) ======

<span style="color: #ff0000; font-family: Tahoma,Geneva,sans-serif; font-size: 120%;">__Empirical Formulas 309-310 (Emily Tormey)__
<span style="font-family: Tahoma,Geneva,sans-serif; font-weight: normal; letter-spacing: 0px;">*** a basic ration that gives the lowest whole-number of the atoms of the elements in a compound** <span style="font-family: Tahoma,Geneva,sans-serif; font-weight: normal; letter-spacing: 0px;">-An empirical formula uses the data <span style="font-family: Tahoma,Geneva,sans-serif; font-size: 12px;">from the percent composition of a synthesized compound to determine the basic ratio of elements found in the compound <span style="font-family: Tahoma,Geneva,sans-serif; font-weight: normal; letter-spacing: 0px;">-The empirical formula shows the kind of and lowest relative count of atoms or moles of atoms in molecules <span style="font-family: Tahoma,Geneva,sans-serif; font-weight: normal; letter-spacing: 0px;">-It is not always consistent with the molecular formula <span style="font-family: Tahoma,Geneva,sans-serif; font-weight: normal; letter-spacing: 0px;">**-ex: empirical formula of hydrogen peroxide is HO, the molecular formula is <span style="font-family: Tahoma,Geneva,sans-serif; font-size: 12px;">H2O2 ** <span style="font-family: Tahoma,Geneva,sans-serif; font-weight: normal; letter-spacing: 0px;">**-Some times the empirical and molecular formulas are the same** <span style="font-family: Tahoma,Geneva,sans-serif; font-weight: normal; letter-spacing: 0px;">**-ex: carbon dioxide's empirical formula is CO2 and the molecular formula is CO2** <span style="font-family: Tahoma,Geneva,sans-serif; font-weight: normal; letter-spacing: 0px;">-This is because that is the most basic ratio to form a carbon dioxide molecule

//<span style="color: #008000; font-family: Arial,Helvetica,sans-serif; font-style: normal; letter-spacing: 0px;">A compound is analyzed and found to contain 25.9% nitrogen and 74.1% oxygen. What is the empirical formula of this compound? // //<span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">what needs to be found? - //<span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">Empirical Formula <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">2<span style="font-family: Tahoma,Geneva,sans-serif;">) //Solve for the unknowns:// <span style="color: #000000; font-family: Tahoma,Geneva,sans-serif; letter-spacing: 0px;">Percent is equal to # of parts in 100 parts so 100 g of compound contains 25.9 g N, and 74.1 g O. <span style="color: #000000; font-family: Tahoma,Geneva,sans-serif; letter-spacing: 0px;">25.9 <span style="font-family: Tahoma,Geneva,sans-serif;"><span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px; text-decoration: line-through;">g N <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;"> x (1 mol N)/(14.0 <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px; text-decoration: line-through;">g N <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">) = 1.85 mol N  <span style="font-family: Tahoma,Geneva,sans-serif;"><span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">74.1 <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px; text-decoration: line-through;">g O <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;"> x (1 mol O)/(16.0 <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px; text-decoration: line-through;">g O <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">) = 4.63 mol O  <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">Must be in whole number ratios. <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">(1.85 mol N)/(1.85) = 1 mol N <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">(4.63 mol O)/(1.85) = 2.50 mol O <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">Still Must be in whole number ratios (multiply by smallest whole number). <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">1 mol N x 2 = 2 mol N <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">2.5 mol O x 2 = 5 mol O <span style="font-family: Tahoma,Geneva,sans-serif; letter-spacing: 0px;">**<span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">Empirical Formula is N₂O₅ ** <span style="font-family: Tahoma,Geneva,sans-serif; letter-spacing: 0px;">**<span style="color: #000000; font-family: Arial,Helvetica,sans-serif; font-weight: normal; letter-spacing: 0px;">3) //Check your answer:// ** <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">Subscripts should be whole numbers, and if you do percent composition from this formula it should equal % composition in the original question.
 * sample problem:** //<span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">**Determining the Empirical Formula of a Compound (Chad Benoit)** //
 * <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;"> 1) <span style="color: #ff0000; font-family: Helvetica,helvetica,sans-serif; font-weight: normal;"> //<span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">what is known? - // <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">percent of nitrogen (25.9%), percent of oxygen (74.1%)  **

[|Empirical Formula Calculator and further explanation]
 * info by John G.**

<span style="color: #ff0000; font-family: Tahoma,Geneva,sans-serif; font-size: 120%;">__Molecular Formulas 311-312 (Brendan O'Neil)__
==<span style="color: #000000; font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: 115%;">The molecular formula of a compound is either the same as its experimentally determined empirical formula, or it is a simple whole-number multiple of its empirical formula. == ==<span style="color: #000000; font-family: Tahoma,Geneva,sans-serif; font-size: 120%;"> · <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: 115%;">Once you have determined the empirical formula of your synthesized compound, you can determine its molecular formula, but you must know the compound’s molar mass == ==<span style="color: #000000; font-family: Tahoma,Geneva,sans-serif; font-size: 120%;"> o <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: 115%;">A chemist uses an instrument called a mass spectrometer to determine molar mass == ==<span style="color: #000000; font-family: Tahoma,Geneva,sans-serif; font-size: 120%;"> o <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: 115%;">The compound is broken into charged fragments, or ions, that travel through a magnetic field. == ==<span style="color: #000000; font-family: Tahoma,Geneva,sans-serif; font-size: 120%;"> o <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: 115%;">The magnetic field deflects the particles from their straight-line paths, and the amount of deflection experienced by the particles determines the mass of the compound. == ==<span style="color: #000000; font-family: Tahoma,Geneva,sans-serif; font-size: 120%;"> · <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: 115%;">From the empirical formula, you can calculate the empirical formula mass. == <span style="font-family: Tahoma,Geneva,sans-serif; letter-spacing: 0px;">**<span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">sample problem: //<span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">Finding the Molecular Formula of a Compound (Chad Benoit) //** <span style="font-family: Tahoma,Geneva,sans-serif; letter-spacing: 0px;">**<span style="color: #008000; font-family: Arial,Helvetica,sans-serif;">Calculate the molecular formula of a compound whose molar mass is 60.0 g/mol and empirical formula is CH₄N. ** <span style="font-family: Tahoma,Geneva,sans-serif;"><span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">1) //<span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">What is known? - // <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">empirical formula (CH₄N), molar mass (60.0 g/mol) <span style="font-family: Tahoma,Geneva,sans-serif;"> //<span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">What needs to be found? - // molecular formula <span style="font-family: Tahoma,Geneva,sans-serif;">2) //Solve for the unknowns:// <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; letter-spacing: 0px;">3) //Check your answer:// <span style="color: #000000; font-family: Arial,Helvetica,sans-serif;">The molecular formula should have the same molar mass as the compound.
 * <span style="font-family: Tahoma,Geneva,sans-serif;">calculate empirical formula mass
 * <span style="font-family: Tahoma,Geneva,sans-serif;">divide molar mass by the empirical formula mass (efm) to get whole number
 * <span style="font-family: Tahoma,Geneva,sans-serif;">multiply the formula subscripts by this value
 * <span style="color: #000000; font-family: Tahoma,Geneva,sans-serif; letter-spacing: 0px;">Empirical Formula || <span style="color: #000000; font-family: Tahoma,Geneva,sans-serif; letter-spacing: 0px;">efm || <span style="color: #000000; font-family: Tahoma,Geneva,sans-serif; letter-spacing: 0px;">Molar mass/ efm || <span style="color: #000000; font-family: Tahoma,Geneva,sans-serif; letter-spacing: 0px;">**Molecular Formula** ||
 * <span style="color: #000000; font-family: Tahoma,Geneva,sans-serif; letter-spacing: 0px;">CH₄N || <span style="color: #000000; font-family: Tahoma,Geneva,sans-serif; letter-spacing: 0px;">30.0 || <span style="color: #000000; font-family: Tahoma,Geneva,sans-serif; letter-spacing: 0px;">60.0/30.0 = 2 || <span style="color: #000000; font-family: Tahoma,Geneva,sans-serif; letter-spacing: 0px;">**C₂H₈N₂** ||

=<span style="color: #ff0300; font-family: Tahoma,Geneva,sans-serif; font-size: 120%;">__Key Points From Section 3 (Olivia Cortellini)__ =
 * 1) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">Percent composition is the percent by mass of each element in a compound and can be found by dividing the mass of the element by the mass of the compound and multiplying it by 100%. It can be calculated with information taken from mass data or a chemical formula.
 * 2) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">An empirical formula is the basic ratio of elements contained in a compound. It may or may not be the same as a molecular formula, but it always shows the smallest whole-number ratio of atoms in a compound.
 * 3) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 110%;">A molecular formula shows the kinds and numbers of atoms present in a molecule of a compound. It is always either the same as the compounds empirical formula, or a whole-number multiple of its empirical formula.


 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 130%;">Need extra help with this section? Take a look at these links! **

[|Quiz on Empirical and Molecular Formulas]
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The Mole: A Measurement of Matter (Mary Katherine Runey)

Measuring Matter 1) Count (example: 3 pieces of paper) 2) Mass (example: I weigh 110 lbs.) 3) Volume (example: 1 liter of soda)
 * We live in a quantitative world- numbers are a part of our lives!
 * We often measure the amount of something by three different meathods

What is a Mole?
 * Just as a dozen is a unit of 12 things; Chemists use a unit that is a specified number of particles-mole (mol)
 * a mole of a substance is 6.02 X 10^23 representative particles of that substance and is the SI unit for measuring the amount of a substance
 * 6.02 X 10^23 is also known as Avogadro's number- An Italian scientist who clarified the difference between atoms and molecules
 * Representative Particles- The species present in a substance: atoms, molecules, etc.