practice with molar mass problems
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Practice with Molar Mass Practice with Molar Mass ProblemsProblems
::Question #1Question #1
How many moles of H2 are in 100 g of H2?
# mol H2 = 100 g H2x 1 mol H2
2.02 g H2
= 49.5 mol H2
Question #2Question #2
300 g of CuSO4 is needed in an experiment. How many moles does this represent?
# mol CuSO4 =
300 g CuSO4 x 1 mol CuSO4
159.61 g CuSO4
= 1.88 mol CuSO4
Question #3Question #3
A chemical reaction requires 23.78 moles of silver chloride. How many grams is this?
# g AgCl =
23.78 mol AgCl x 143.32 g AgCl
1 mol AgCl= 3408 g AgCl
73 g H2O
Question #4Question #4
How many molecules are in 73 grams H2O?
# H2O molecules =
x 1 mol H2O
18.02 g H2O
= 2.4 x 1024 molecules H2O
x 6.02x1023 molecules
1 mol H2O
Question #5Question #5
255 g of calcium phosphate are produced in a chemical reaction. How many moles of calcium phosphate does this represent?
# mol Ca3(PO4)2 =
255 g Ca3(PO4)2 x 1 mol Ca3(PO4)2
310.18 g Ca3(PO4)2
= 0.822 mol Ca3(PO4)2
Question #6Question #6
According to the equation 2H2 + O2 2H2O, how many grams of H2O would be produced if 7.35 mol of O2 is used up? (hint: you will need two conversion factors – 1 from the balanced equation and 1 from a molar mass)
2 mol H2O
1 mol O2
x
# g H2O=
7.35 mol O2 265 g H2O
= 18.01 g H2O
1 mol H2Ox
And you thought Chemistry was And you thought Chemistry was bad with factor-label problems!!??bad with factor-label problems!!??
Complete the following chart (#7 - #13):
Formula Molar mass
(g/mol)
Mass
(g)
Moles
(mol)
FeSO4 500
(NH4)2CO3 2
SnO2 50
Sb2O5 0.25
NaClO4 100
Mg(IO3)2 3.2
CoCl2.H2O 332
Complete the following chart (answers):
2.246332147.8CoCl2.H2O
3.21196.8374.1Mg(IO3)2
0.817100122.4NaClO4
0.2580.9323.6Sb2O5
0.33250150.7SnO2
2192.296.1(NH4)2CO3
3.29500151.9FeSO4
Moles
(mol)
Mass
(g)
Molar mass
(g/mol)
Formula
AssignmentAssignment
14. AgCl = 143.35 g/mol#g = 2 mol x 143.35 g/mol = 286.7 g (2)
15. H2 = 2.016 g/mol
#mol = 100 g x mol/2.016 g = 49.6 mol (2)
16. CuSO4 = 159.62 g/mol
#mol= 300 g x mol/159.62 g =1.879 mol (2)
17. KClO = 90.55 g/mol#mol = 250 g x mol/90.55 g = 2.76 mol (2)
Extra Review Mass-Mole-Molecules: Extra Review Mass-Mole-Molecules: Determine the number of molecules in Determine the number of molecules in 73 g of water73 g of water
73 g H2O
# H2O molecules =
x 1 mol H2O
18.02 g H2O
= 2.4 x 1024 molecules H2O
x 6.02x1023 molecules
1 mol H2O
Try this one:Try this one:
Calculate the mass in grams of iodine required to react completely with 0.50 moles of aluminum.
Al + I2 AlI32 Al + 3 I2 2 AlI3
= 190 g I2
0.50 mol Al x 3 mol I2 2 mol Al
x 253.80 g I2
1 mol I2
0.50 g Al
Try this one:Try this one:
Calculate the mass in grams of iodine required to react completely with 0.50 g of aluminum.
Al + I2 AlI32 Al + 3 I2 2 AlI3
= 7.1 g I2
x 3 mol I2 2 mol Al
x 253.80 g I2
1 mol I2
x 1 mol Al
26.98 g Al
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