Transcript
The Mole
http://www.hannibal.cnyric.org/teacherwebs/scianfarano/chemistry/moles_and_stoichiometry_notes.htm
http://www2.waterforduhs.k12.wi.us/staffweb/smith/Nancy/chemistry/MOLE%20%20DAY%20%20PROJECTS%202006.htm
Counting Units
1 pair of objects = 2 objects
1 dozen objects = 12 objects
1 gross of objects = 144 objects
1 ream of objects = 500 objects
2.010 x 10-23 g/atom is a very small amount.
Scientists cannot measure small quantities like this in the lab. Scientists want (NEED!) to be able to work with a useable quantity such as 10 grams or 50 grams.
Is there a convenient way to measure larger quantities of atoms?
But the atomic mass on the chart is in AMU, not grams! We do not have an AMU balance!
Then let’s convert the number on the periodic chart from AMU to grams!Which number Does that??
A MOLE (mol) is just a word representing a quantity.
What does dozen mean? Yep, it means 12. But 12 what?
12 steers 12 dinosaurs
12 flags
1 pair of objects = 2 objects
1 dozen objects = 12 objects
1 gross of objects = 144 objects
1 ream of paper = 500 sheets
1 mole of objects = 6.022 x 1023 objects
1 mole of apples = 6.02 x 1023 apples
1 mole of diamonds = 6.02 x 1023 diamonds
1 mole of baseballs = 6.02 x 1023 baseballs
1 mole of carbon atoms = 6.02 x 1023 carbon atoms
Just like the word dozen can stand for 12 things, the mole stands for
6.02 x 1023 things.
Things, however, are limited to
Atoms Molecules Ions
You have finally arrived at the MOLE: The mole is nothing more than the basic counting unit in chemistry for atoms, molecules and other very small particles.
You can now start applying this new knowledge in many different ways!
http://www.nclark.net/MolesMoleculesWorksheet.pdf
This is easy! We just learned that 1 mole of an element is equal to the atomic mass listed on the periodic table.
1 mole of Cu atoms has a mass of 63.5 grams.
What Is The Mass Of 1 Mole Of Cu Atoms?
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Remember, 1 atom of Cu has a mass of 63.5 amu. 1 mole of Cu atoms has a mass of 63.5 grams!
How many atoms of Cu are present in 200 g of Cu?
You have to expand your mind a bit on this one. Is there a directconversion between numbers of atoms and grams of an element?
NO!
Well, what do we know that will help us, then?
• We know there are 6.02 X 1023 atoms in a mole of something.
• We know 63.5 g of Cu is equal to one mole of Cu atoms.
How can we use these two facts to help us solve the problem?
How many atoms of Cu are present in 200 g of Cu?
1. Find out how many moles is equal to 200 g Cu.2. Find out how many atoms there are in this many moles.
1. Molar mass Cu = 63.5 g/mol Use this as a proportion!
63.5 g Cu 200 g Cu------------ = ------------- x = 3.15 moles Cu1 mole x mole
2. There are 6.02 X 1023 atoms of Cu in a mole of Cu.
6.02 X 1023 atoms Cu x atoms Cu--------------------------- = ------------------- x = 1.9 X 1024 atoms 1 mole Cu 3.15 moles Cu of Cu
How many atoms of Cu are present in 200 g of Cu?
1mole Cu 6.02 x 1023 atoms Cu200 g Cu x ------------- x -------------------------- =
63.5 g Cu 1 mole Cu
A much shorter way…Dimensional Analysis!
x = 1.9 X 1024 atoms of Cu
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Stuff to Do With the Mole
What is the mass of 1 mole of Cu atoms?
How many moles of Cu atoms are there in 75 g
of Cu?
How many atoms of Cu are present in
200 g of Cu?
What is the mass of 1 mole of Cu(NO3)2?
How many moles of Cu(NO3)2 are there in 150 g of Cu(NO3)2?
Moles and VolumeWe can also determine a mole by using volume , although this would pertain only to gases.
Under standard conditions (STP) of pressure and temperature, which is defined as 1 atm and 0oC, one mole of any gas would occupy 22.4 liters. This is called a molar volume.
1. How many moles of carbon dioxide, at STP, would be present in 5.6 liters of the gas?
2. What is the volume of 0.35 mol of oxygen gas at STP?
A. 32 L
B. 64 L
C. 7.8 L
D. 16 L
How many liters of oxygen will be produced if 61 grams of potassium chlorate (KClO3) is decomposed?
KClO3 => KCl + O2
http://www.sparknotes.com/testprep/books/sat2/chemistry/chapter7section3.rhtml
Solid lithium hydroxide is used in space vehicles to remove exhaled carbon dioxide from the air; it reacts with carbon dioxide to form solid lithium carbonate and liquid water. What mass of gaseous carbon dioxide will be consumed in a reaction with 1.00 kg of lithium hydroxide?
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