Conceptual Chemistry : Conceptual Chemistry Measuring Matter
Objectives : Objectives Define the mole and Avogadro’s Number.
Convert between moles and number of particles.
Matter : Matter All matter is made of particles
Atoms
Molecules
Diatomic elements
Molecular compounds
Ions
Cations
Anions
Formula units of Ionic compounds
The Mole : The Mole Particles in matter are very small
Too small to see
Too small for a microscope
Counting particles is not possible
Chemists use the mole to count particles
The Mole : The Mole The mole is a unit for measuring the amount of a substance
Mole is abbreviated mol
One mole is 6.02 x 1023 particles
The Mole : The Mole Look at the objects on the lab bench.
How are these groups of objects similar?
Paper clips
m & m’s
Atomic models
Pencils
Beakers
Books
Tape dispensers
Bottles
How many? : How many?
12 of each item : 12 of each item
Another name for 12 items? : Another name for 12 items?
One dozen items = 12 items : One dozen items = 12 items
Everyone knows a dozen is 12 : Everyone knows a dozen is 12
The item doesn’t matter : The item doesn’t matter
1 dozen = 12 items : 1 dozen = 12 items
2 dozen = 24 items : 2 dozen = 24 items
The Mole : The Mole Look at the objects on the teacher’s desk.
How are these groups of objects similar?
12 Paper clips
12 m & m’s
12 Atomic models
12 Pencils
12 Beakers
12 Books
12 Tape dispensers
12 Bottles
The Mole : The Mole You could say we have a dozen of each object.
1 dozen Paper clips
1 dozen m & m’s
1 dozen Atomic models
1 dozen Pencils
1 dozen Beakers
1 dozen Books
1 dozen Tape dispensers
1 dozen Bottles
The Mole : The Mole A dozen of any object would contain 12 of the objects.
A mole is similar to a dozen
The number of objects in a mole is a much larger number.
Number in a mole. : Number in a mole. The number is
602
Number in a mole. : Number in a mole. The number is
602 000
Number in a mole. : Number in a mole. The number is
602 000 000
Number in a mole. : Number in a mole. The number is
602 000 000 000
Number in a mole. : Number in a mole. The number is
602 000 000 000 000
Number in a mole. : Number in a mole. The number is
602 000 000 000 000 000
Number in a mole. : Number in a mole. The number is
602 000 000 000 000 000 000
Number in a mole. : Number in a mole. The number is
602 000 000 000 000 000 000 000
Number in a mole. : Number in a mole. The number is
602 000 000 000 000 000 000 000
We will write it as 6.02 x 1023
The Mole : The Mole A second name for the number 6.02 x 1023 is Avogadro’s number.
Avogadro was a chemist who studied atoms and molecules and was among the first to explain the difference between atoms and molecules.
Mole-Particle Conversions : Mole-Particle Conversions If you have 6.02 x 1023 particles, you have 1.00 moles of particles.
If you have 9.03 x 1023 particles, you have 1.50 moles of particles.
If you have 3.01 x 1023 particles, you have 0.500 moles of particles.
Sample Problem : Sample Problem How many atoms are in 2.00 mol of argon?
Sample Problem : Sample Problem How many atoms are in 2.00 mol of argon? Use the factor label method to solve this problem.
Sample Problem : Sample Problem How many atoms are in 2.00 mol of argon? Use the factor label method to solve this problem.
It will help you decide when to multiply or divide.
Sample Problem : Sample Problem How many atoms are in 2.00 mol of argon? Write the number from the problem in the space where you are going to show your work.
Sample Problem : Sample Problem How many atoms are in 2.00 mol of argon? Write the number from the problem in the space where you are going to show your work.
Sample Problem : Sample Problem How many atoms are in 2.00 mol of argon? Remember, the process is always written as multiplication.
Sample Problem : Sample Problem How many atoms are in 2.00 mol of argon? And, you always multiply by a fraction.
Sample Problem : Sample Problem How many atoms are in 2.00 mol of argon? The bottom of the fraction has a unit that matches the unit of the given amount from the problem.
Sample Problem : Sample Problem How many atoms are in 2.00 mol of argon? The top of the fraction has a unit that matches the unit in the question in the problem.
Sample Problem : Sample Problem How many atoms are in 2.00 mol of argon? Now, put the numbers in that make the top and bottom equal.
Sample Problem : Sample Problem How many atoms are in 2.00 mol of argon? Cross out the matching units.
Sample Problem : Sample Problem How many atoms are in 2.00 mol of argon? Finally, use the calculator
Sample Problem : Sample Problem How many atoms are in 2.00 mol of argon? Put the given number into the calculator.
Sample Problem : Sample Problem How many atoms are in 2.00 mol of argon? Multiply by the number on the top and divide by the number on the bottom. Read your calculator’s manual for instructions on putting this number into your calculator!
Sample Problem : Sample Problem How many atoms are in 2.00 mol of argon? Write the answer.
Sample Problem : Sample Problem How many moles are in 4.35 x 1024 molecules of carbon dioxide? Try this one.
Sample Problem : Sample Problem How many moles are in 4.35 x 1024 molecules of carbon dioxide? Start with the number from the problem.
Sample Problem : Sample Problem How many moles are in 4.35 x 1024 molecules of carbon dioxide? Set up the units of the conversion factor.
Sample Problem : Sample Problem How many moles are in 4.35 x 1024 molecules of carbon dioxide? Fill in the numbers to make the values of top and bottom equal.
Sample Problem : Sample Problem How many moles are in 4.35 x 1024 molecules of carbon dioxide? Cancel the units.
Sample Problem : Sample Problem How many moles are in 4.35 x 1024 molecules of carbon dioxide? Calculate the answer.
Sample Problem : Sample Problem How many formula units are in 3.15 mol of sodium oxide? Notice this asks for formula units since sodium oxide is ionic.
Sample Problem : Sample Problem How many formula units are in 3.15 mol of sodium oxide? Number from problem
Sample Problem : Sample Problem How many formula units are in 3.15 mol of sodium oxide? Put in the factor.
Sample Problem : Sample Problem How many formula units are in 3.15 mol of sodium oxide? Put in the factor.
Sample Problem : Sample Problem How many formula units are in 3.15 mol of sodium oxide? Calculate the answer.