Mole _2_.ppt by changcheng2

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									  Chemistry
      5072
Avogadro’s Constant
                         Mass of 1 atom
• What is the mass of 1 proton?
     1.67 X 10-24g
 o What is the mass of 1 neutron?

      1.67 X 10-24g
 o   What is the mass of one Hydrogen atom?

      1.67 X 10-24g
     Because hydrogen atom has only one proton
               Mass of 1 atom ctd…
• What is the mass of 1 carbon atom?
     12 X 1.67 X 10-24g
 o   What is the mass of 1 sodium atom?

      23 X 1.67 X 10-24g
                                         Molar mass
           4                            32
           2   He                       16   S

          24                             12
          12   Mg                         6   C

Let’s take the mass number as the mass in gram, how many atoms
are there? (i.e. how many atoms are there in 4g of He?)
           Avogadro’s constant
• Well, you know that given the mass
  number in grams, there are 6 X 1023
  atoms/particles.
• 6 X 1023 is a constant number and this is
  termed as Avogadro’s constant.
• 4g of He, 32g of S, 24g of Mg and 12g of
  C contain 6 X 1023 particles. The mass
  which gives 6 X 1023 particles is termed
  as Molar mass!
                                 Mole
• One mole of any substance contains 6 X
  1023 of particles.
• Therefore, molar mass of Na is
  23g/mol.
• How about molar mass of:
  a)Zn
  b)Si
  c)Ar
  d)Ca
                                           Analogy



     Mass of 1 orange = mass of 1 apple = 10g
                 Mass of basket = 0g

If the basket can contains 2 apples and 2 oranges,
                                                     40g
        what is the mass of the basket now?



If one container can take in 10 baskets,
what is the mass of the container?                   400g
                     Analogy ctd…




      Mass of 1 orange = mass of 1 apple = 10g
                    Mass of basket = 0g

If the basket can contains 5 apples and 5 oranges,
                                                     100g
        what is the mass of the basket now?

 If one container can take in 10 baskets,            1000g
 what is the mass of the container?
                                                          Analogy
      proton                                                           neutron


nucleus




               Mass of 1 orange = mass of 1 apple = 10g                  Mass
                           Mass of basket = 0g                           number

                  If the basket can contains 2 apples and 2 oranges,
                          what is the mass of the basket now?              40g

                    mole                  Avogadro’s constant

                    If 1 container can take in 10 baskets,                    Molar
                    what is the mass of the container?                        mass
                                                                       400g
                                      Mole
• 1 mole of any substance contains 6 X 1023
  particles.
• How many particles are there in 2 moles of
  Na?
  1.2 X 1024 particles of Na
o How many particles are there in 3 moles of
  C?
  1.8 X 1024 particles of C
o How many particles are there in 0.25 of Ti?
  1.5 X 1023 particles of Ti
                             Mole ctd…
• If there are 4 X 1023 particles of Mg, how
  many moles of Mg are there?
  4 X 1023 particles = 0.667 moles (3 sf)
  6 X 1023 particles
• If there are 1.5 X 1022 particles of He, how
  many moles of He are there?
  1.5 X 1022 particles = 0.0250 moles (3 sf)
   6 X 1023 particles
         Number of
          particles

X (6X1023)          ÷
                    (6X1023)




             Mole

								
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