Transcript 1 mole

CHEMISTRY
Feb 22, 2011
Warm Up
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Find the molar mass of these substances
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Fe3N2
Mg(OH)2
Agenda
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Warm Up
Unit 8 Notes
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Practice Problems
Homework
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Intro to Moles and Stoichiometry
Unit 8 Worksheet 1
Reminder:
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Test Make Up
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Wednesday, Thursday, or Friday ONLY
Are these moles?
What is a mole?
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A unit of measurement
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Since the numbers in chemistry are so small,
we use a “preferred unit of measurement”
(mole) to represent the small number
What are the units of measurement?
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"that equal number" of atoms randomly chosen.
the number of atoms in the atomic weight in g of any
element.
the number of atoms in 16 g of oxygen, in 4 grams of
He, in 32 g of sulfur, etc.
the number of molecules in the molecular weight, in
grams, of any compound.
the number of molecules in 18 g of water, in 40 g of
lithium carbide.
Much later, a mole, that equal number, was found to be
6.022 x 1023(representative particles).
Examples
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1 mole (or abbr. mol) = 12.011 g of Carbon
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1 mol of Carbon = 6.02 x 1023 atoms of C
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1 mol of H2O = 6.02 x 1023 molecules of
water
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1 mol of NaCl = 6.02 x 1023 units of NaCl
Figure 8.1: All these samples of pure elements contain the
same number (a mole) of atoms: 6.022 x 1023 atoms.
Copyright © Houghton Mifflin Company.All rights reserved.
8–5
Moles in mass
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1 mole can equal the atomic weight of an
element.
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1mol of C = 12.011g of C
1 mole can equal the atomic weight of a
compound
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1mol of CO = 12.011g of C + 15.99 g of O
= 28.0 g of CO
Practice Problems
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How many grams of Cu are in 1.20 mol of
Cu?
How many moles are in 70g of Cl?
Moles in compounds
Let’s say you have water aka. H2O
How many moles of Hydrogen atoms(ions) are
in water?
 Ask yourself how many individual atoms of
Hydrogen do you see in water?
 Did you say 2???
 Is that your final answer?
 You are correct! So how many mols of
Oxygen atoms do you see?
Moles in an equation
2 H2 + O2  2H2O
How many moles of Hydrogen molecules are in
the reactants?
*Coefficients serve as the number of moles too!
Therefore, there are 4 mols of Hydrogen gas
NOPE!!!! Fooled you.. 2 mols of Hydrogen gas
Molecules
Atoms
Units
Mole Conversion
Boomerang
Mole Conversions
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Mass to mole or vice versa:
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How many moles are in 24 g of Carbon?
Look at the boomerang:
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Start with the given: 24 g (mass) of C
What do you want in the end? Moles of C
Use the conversion factor given:
1 mole
Atomic mass
24 g of C x 1 mol of C = 2.0 mol of Carbon
12.011 g of C
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White Boards
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Given 200 g of water, how many mols of
water do you have?
How many grams of carbon monoxide are in
1.5 mols of carbon monoxide?
More conversion
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Mole to atoms/molecules/particles or vice versa
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How many atoms are in 2.00 mols of Carbon?
Look at the boomerang:
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Where do you begin? (the given: mols)
What do you need in the end? (atoms: particles)
What’s the conversion factor?
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6.02 x 1023 Atoms of C
1 Mols of C
2.00 mols of C x 6.02 x 1023 atoms of C = 1.20 x 1024 atoms C
1 mol of C
White boards
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How many molecules of oxygen gas are in
3.0 mols of Oxygen gas?
How many mols of Oxygen gas are in
4.67 x 1024 molecules of Oxygen gas?
More conversion
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Mole to volume of gas or vice versa
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What is the volume occupied by 2 mols of hydrogen gas?
Look at the boomerang:
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Where do you begin? (the given: mols)
What do you need in the end? (volume of gas)
What’s the conversion factor?
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22.4 L of H2
1 Mols of H2
2.00 mols of H2 x 22.4 L of H2 = 44.8 L of H2
1 mol of H2
White boards
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Convert 4.38 moles of He to liters
Convert 3.01 L of N to moles
Practice
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Must show work (dimensional analysis)
How many grams are in 1 mol of Mercury?
Given a 1.5 mols of carbon dioxide, how
many molecules of carbon dioxide do you
have?
Homework
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Mole Conversion Worksheet 1