Avogadro s number
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Avogadro’s Number. 6.02x10 23. mole = (mol) 602000000000000000000000. Mole. A mole is just a number like… Pair = 2Trio = 3 Dozen = 12Baker’s dozen = 13 Gross = 144Score= 20 Century=100Ream=500. How BIG is a mole?. There are ~ 6.6 billion people on Earth

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Avogadro’s Number

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Avogadro s number

Avogadro’s Number

6.02x1023


Avogadro s number

mole = (mol) 602000000000000000000000

Mole

  • A mole is just a number like…

    Pair = 2Trio = 3

    Dozen = 12Baker’s dozen = 13

    Gross = 144Score= 20

    Century=100Ream=500


How big is a mole

How BIG is a mole?

There are ~ 6.6 billion people on Earth

How many Earths would it take to equal the population

of 1 mole?

9.12 x 1013


Avogadro s number

  • If you spent $800 billion dollars a day how many years would it take to spend a MOLEion dollars?

2.06 x 109 years


Avogadro s number

  • If you had a mole of cats . . .

    They would create a sphere

    larger than

    Earth!


Avogadro s number

  • If you had a mole of H2O could you swim in it?

    NO! 

    Water molecules are so small

    that a mole of H2O = 18ml


Avogadro s number

  • In chemistry we don’t work with individual atoms or molecules because they are too small to be weighed or measured

  • We have to work with LOTS of atoms in order to measure them

    THAT’s WHERE THE

    MOLE COMES IN!


How small are atoms

How small are atoms?

  • There are more atoms in one gram of salt than grains of sand on all the beaches

    of all the oceans in all

    the world.


Gram atomic mass

of the

in

Gram ATOMic Mass

  • mass is in grams of 1 mole of atoms of an element

  • In other words……

    1 mol C atoms = 6.02 x 10 23 C atoms = 12g C


Practice remember 1 mole 6 02x10 23 atoms or molecules g from the periodic table

PracticeRemember . . .1 mole = 6.02x1023atoms or molecules =______ g from the periodic table


Stoich iometry of chemical formulas

Stoichiometry of Chemical Formulas


Gram formula mass gram molecular mass molar mass

of the

in

Gram Formula MassGram Molecular Mass Molar Mass

  • mass in grams of 1 mole of a substance

  • In other words . . . Add it all up!

    1 mole of NaCl = 58g = 6.02x1023 particles of NaCl

    1 mole of H2O = 18g = 6.02x1023 molecules of H20


Avogadro s number

Now…..

  • Use the gram formula mass and the gram atomic mass to determine

    • how many moles or atoms of an element are found in some mass of a substance

    • how much mass that element contributes to the mass of the entire substance

      Use factor label & follow the units!


Stoich iometry of chemical formulas1

Stoichiometry of Chemical Formulas

  • If you have 1 molecule of (NH4)2SO4

    • How many atoms of N are there?

    • How many atoms of H?

      SO…..

  • If you have 1 mole of of (NH4)2SO4

    • How many moles of N are there?

    • How many moles of H?


Avogadro s number

PracticeRemember . . .1 mole = 6.02x1023atoms or molecules =______ gfm from the pt


Molar volume

Gases ONLY

@STP

Molar Volume

  • 1 mole of ANYgas

    O2 (g)

    NH3 (g)

    He (g)

    contains 6.02 x 1023 molecules and

    occupies a volume of 22.4L


Avogadro s number

  • STP

    standardtemperature & pressure

    0oC or 273K

101.3kPa or 1 atm


Remember

Remember . . .

  • Gases also have mass

    1 mole of O2(g) = 32g

    1 mole of NH3(g) = 17g

     we can calculate Density!


D m v

D = m/v

  • A sample of oxygen contains 3 moles of particles at STP what is its density?

  • 2 steps

    • Convert moles to mass AND volume

    • Calculate density

  • If mass or volume is given, use it and convert the other……. THEN calculate D!


Avogadro s number

Remember . . .

1 mole = 6.02x1023atoms or molecules =gfm = 22.4L (g)


Stoich iometry of chemical equations

“it’s a simple matter

of weight ratios . . .”

Stoichiometry of Chemical Equations

  • The study of quantitative relationships that can be derived from chemical equations.


Stoichiometry cookies

Stoichiometry cookies

  • If you look at chemical equations as recipes it may be easier to understand that

    • changing the amount of a reactant will change the amount of the product IN THE SAME RATIO!


Examining molar relationships in balanced equations

Examining Molar Relationships in Balanced Equations

6CO2 + 12 H2O + 2804kJ  6O2 + C6H12O6 +6H20

Balanced equations

  • Law of conservation of mass / matter

    • ATOMS are not createdor destroyed during a chemical reaction, they are only rearranged to form new substances.

    • # atoms on reactant side = # atoms on product side

  • Law of conservation of E

    • E on the reactant side = E on the product side


Mole mole relationships

Mole - Mole Relationships

Practice


The end

The End


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