Unit 7: Chemical Quantities

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Unit 7 Chemical Quantities

• 2-Step Conversions

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After today, you will be able to

• Perform two-step conversions using molar mass and
  representative particles (atoms, molecules, and
  formula units)

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We have already learned

• How to convert moles into particles and vice
  versa by using the conversion factor
• 1 mole 6.02x1023 particles

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• How to convert moles into grams and vice versa by
  using the conversion factor
• 1 mole atomic mass
• in grams

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These two conversion factors can now be combined

• Particles ? Moles ? Grams
• Grams ? Moles ? Particles

6.02x1023
molar mass
6.02x1023
molar mass
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• Example What is the mass of 1.79x1024 formula
  units of K3PO4?

K 1.79x1024 F.U. K3PO4
3 K 3(39.10) 1 P 1(30.97) 4 O 4(16.00)

117.30
U ? g K3PO4
30.97
64.00
212.27
1.79x1024 F.U. K3PO4
1 mol K3PO4 .
212.27 g K3PO4
x
x

6.02x1023 F.U. K3PO4
1 mol K3PO4 .
1
631 g K3PO4