# 11.2 molar mass moles grams by lanyuehua

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• pg 1
```									• Molar Mass = mass in grams of one mole
– Units grams/mole
• For elements, molar mass = atomic mass

H              C               O Mg
1.0           12.0            16.0           24.3
• Why aren’t all atomic masses whole numbers?
– Remember that atomic masses are averages of all the
isotopes
• Molecular mass = protons + neutrons = amu
(amu = atomic mass units)
• Hydrogen atom has 1 proton = 1 amu

• Oxygen atom has 8 protons and 8 neutrons =
16 amu
Calculate the molar mass
• HCl      (think H1Cl1)
1* 1.0 + 1* 35.5 = 36.5 g/mol
• Al2O3
2 * 27.0 + 3 * 16.0 = 102 g/mol
• C25H52
25 * 12.0 + 52 * 1.0 = 352 g/mol
• C6H12O6
6 * 12.0 + 12 * 1.0 + 6 * 16.0 = 180 g/mol
• Mg(ClO3)2
1* 24.3 + 2 * 35.5 + 6 * 16.0 = 191.3 g/mol
Calculate the molar mass

• K3PO4         • (NH4)3PO4
212.3 g/mol     149 g/mol

• Ca3(PO4)2     • BaSO4
310.3 g/mol     233.4 g/mol

• H2SO4         • (NH4)3Fe(CN)6
98.1 g/mol      265.8 g/mol
Find the Molar Mass
• BeF2             • Al(OH)3
47 g/mol           78 g/mol

• K 3P             • Ca(NO3)2
148.3 g/mol        164.1 g/mol

• (NH4)2O          • LiNO3
52 g/mol           68.9 g/mol
Now we can use molar mass to
convert between moles and grams
÷

Mass     Molar Mass
Moles
(grams)

x
• How many grams are in 2 moles of carbon?

• How many moles are in 27 grams of water?
• How many grams are in 0.75 moles of aluminum
hydroxide?

• How many moles are in 475 grams of bromine?
Complete in your notes showing your work!

• Determine the molar mass   • Calculate the moles
–   K3PO4                    – 234 g NaCl
–   Ca3(PO4)2                – 572 g MgCl2
–   HCl                      – 23 g C6H12O6
–   H2O
–   BaSO4                  • Calculate the mass
–   3.45 mol K
–   1.75 mol CO2
–   5.2 mol KNO3
–   4.48 mol Ca3(PO4)2

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