Homework #4 Review
particles
moles
1a. How many F2 molecules are in 0.325 moles of F2 ?
0.325 mol F2 x
6.02 x 1023 F2 molecules
1.00 mol F2
=
1.96 x 1023
F2 molecules
b. How many CdF2 formula units are in 0.750 moles of CdF2 ?
6.02 x 1023 CdF2 formula units
0.750 mol CdF2 x
1.00 mol CdF2
=
4.52 x 1023
CdF2 formula units
particles
2a.
Calculate the moles of CO2 in 3.25 x 1023 molecules of CO2.
3.25 x 1023 molecules CO2 x
b.
moles
1 mol CO2
6.02 x 1023 molecules CO2
= 5.40 x 10-1
mol CO2
Calculate the moles of Ag2CO3 in 7.50 x 1024 formula units of Ag2CO3.
7.50 x 1024
formula units Ag2CO3 x
1 mol Ag2CO3
6.02 x 1023 formula units Ag2CO3
= 1.25 x 101
mol Ag2CO3
3. How many grams are contained in 50.0 moles of Br3O8 ?
moles
Br3O8
50.0 mol Br3O8 x
3 x 79.90 + 8 x 16.00 =
367.7 g Br3O8
1 mol Br3O8
grams
367.7 g/mol
= 1.84 x 104 g Br3O8
4. How many moles are contained in 50.0 grams of Fe3(PO4)2 ?
grams
Fe3(PO4)2
moles
3 x 58.85 + 2 x 30.97 + 8 x 16.00 =
50.0 g Fe3(PO4)2 x
1 mol Fe3(PO4)2
357.49 g Fe3(PO4)2
357.49 g/mol
= 0.140 mol Fe3(PO4)2
grams
moles
particles
5a. What is the mass of 6.33 x 1022 molecules of N2O ?
1.00 mol N2O
6.02 x 1023 N2O molecules
6.33 x 1022 N2O molecules x
44.02 g N2O
1.000 mol N2O
x
= 4.63
g N 2O
b. What is the mass of 4.17 x 1021 formula units of Mg(ClO4)2?
4.17 x
1021
Mg(ClO4)2 formula units
x
x
1.00 mol Mg(ClO4)2
6.02 x 1023 Mg(ClO4)2 formula units
223.21 g Mg(ClO4)2 = 1.55
1.000 mol Mg(ClO4)2
g Mg(ClO4)2
6a.
particles
moles
grams
How many molecules are in 3.88 g of ethane (C2H6)?
3.88 g C2H6
x
1.000 mol C2H6
30.08 g C2H6
x
6.02 x 1023 C2H6 molecules
1.00 mol C2H6
= 7.77 x 1022 C2H6 molecules
b.
How many formula units are in 0.152 g of AlCl3?
0.152 g AlCl3
x 1.000 mol AlCl3
133.3 g AlCl3
23
x 6.02 x 10 AlCl3 formula units
1.00 mol AlCl3
= 6.86 x 1020 AlCl3 formula units