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U3-LM2B-WS Molar Mass and Conversions Name:_____KEY_______
1. The molar mass of chlorine is:
2 x 35.45 g/mol Cl = 70.9 0 g/mol Cl 2 (Remember that chlorine exists as a diatomic molecule in nature)
2. The molar mass of carbon dioxide is:
12.01 g/mol C + (2 x 16.00 g/mol O) = 44.01 g/mol CO 2
3. The molar mass of aluminum carbonate, Al 2 (CO 3 ) 3 , is:
(2 x 26.98 g/mol Al) + (3 x 12.01 g/mol C) + (9 x 16 g/mol O) = 234.0 g/mol Al 2 (CO 3 ) 3
4. The molar mass of ascorbic acid (Vitamin C), C 6 H 8 O 6 is:
(6 x 12.01 g/mol C) + (8 x 1.01 g/mol H) + (6 x 16 g/mol H) = 176.14 g/mol C 6 H 8 O 6
5. A 4.0g/mol represents the molar mass of the element _______________.
6. A 2.0 g/mol represents the molar mass of the element _______________.
7. A 40.0 g sample of sodium is ____________ moles of sodium and ___________
atoms of sodium.
40.0 g Na 1 mol Na = 1.74 moles Na 22.99 g Na 1.74 moles Na 6.022 x 10^23 atoms Na = 1.05 x 10^24 atoms Na 1 mol Na
8. One mole of elemental diatomic chlorine is _____________ grams of chlorine
and contains ____________________atoms of chlorine.
1 mol Cl 2 70.9 g Cl = 70.9 g Cl 1 mol Cl 2 1 mol Cl 2 2 mol Cl 6.022 x 10^23 atoms Cl = 1.20 x 10^24 atoms Cl 1 mol Cl 2 1 mol Cl
helium
hydrogen
1.74 1.05 x 10
24
1.20 x 10^24
9. If 2 moles of magnetite, Fe 3 O 4 , are needed, one needs to weigh ____________
grams of the substance. This amount corresponds to _______________ formula
units and it contains __________ ions of iron and ____________ions of oxygen.
2 mol Fe 3 O 4 6.022 x 10^23 formula units Fe 3 O 4 = 1.20 x 10^24 formula units Fe 3 O 4 1 mol Fe 3 O 4 1.20 x 10^24 formula units Fe 3 O 4 3 ions Fe = 3.61 x 10^24 ions Fe 1formula unit Fe 3 O 4 1.20 x 10^24 formula units Fe 3 O 4 4 ions O = 4.82 x 10^24 ions O 1 formula unit Fe 3 O 4
10. A sample that is 36.0 grams of water represents _________ moles of water. It
contains _____________ grams of hydrogen and ______________ grams of
oxygen. It also contains ____________ moles of H atom and _________moles of
O atoms. This sample also represents _____________ molecules of water,
___________ atoms of hydrogen and _______________ atoms of oxygen.
36.0 g H 2 O 1 mol H 2 O = 2 mol H 2 O 18 g H 2 O 2 mol H 2 O 2 mol H = 4 mol H 1 g H = 4 g H 1 mol H 2 O 1 mol H 2 mol H 2 O 1 mol O = 2 mol O 16 g H = 32 g H 1 mol H 2 O 1 mol H 2 mol H 2 O 6.022 x 10^23 molecules H 2 O = 1.20 x 10^24 molecules H 2 O 1 mol H 2 O 2 mol H 2 O 1 mol O 6.022 x 10^23 atoms O = 1.20 x 10^24 atoms O 1 mol H 2 O 2 mol H 2 O 6.022 x 10^23 molecules H 2 O = 1.20 x 10^24 molecules H 2 O 1 mol H 2 O
11. a-Calculate the mass in grams of 2.5 moles of calcium.
2.5 mol Ca 40.08 g Ca = 1.0 x 10^2 g Ca 1 mol Ca
b-How many atoms are there is 20.0 grams of calcium?
20.0 g Ca 1 mol Ca 6.022 x 10^23 atoms Ca = 3.00 x 10^23 atoms Ca 40.08 g Ca 1 mol Ca
two
3.61 x 10^24 4.82 x 10^24
1.20 x 10^24
2.41 x 10^24 1.20 x 10^24
b- How many moles of H atoms and how many atoms of H does the above sample
contain?
5.6 mol CH 3 COOH 4 mol H = 22.4 mol H 1 mol CH 3 COOH 22.4 mol H 6.022x10^23 atom H = 1.35 x 10^25 atoms H 1 mol H
c-What is the mass of acetic acid that contains 4.0 g of hydrogen?
4.0 g H 1 mol H 1 mol CH 3 COOH 60.06 g CH 3 COOH = 60.06 g CH 3 COOH 1 g H 4 mol H 1 mol CH 3 COOH
d-What is mass of acetic acid that contains 32.0 g of oxygen?
32.0 g O 1 mol O 1 mol CH 3 COOH 60.06 g CH 3 COOH = 60.06 g CH 3 COOH 16 g O 2 mol O 1 mol CH 3 COOH
e-What mass of acetic acid contains 48.0 grams of carbon?
48.0 g C 1 mol C 1 mol CH 3 COOH 60.06 g CH 3 COOH = 120.12 g CH 3 COOH 12 g C 2 mol C 1 mol CH 3 COOH
14. There are 737 g of sodium chloride in a can of salt.
a-How many moles of sodium chloride does the can of salt contain?
737 g NaCl 1 mol NaCl = 12.6 mol NaCl 58 .44 g NaCl
b-How many formula units of salt does the can of salt contain?
12.6 mol NaCl 6.022 x 10^23 formula unit NaCl = 7.59 x 10^24 formula unit NaCl 1 mol NaCl
c-Calculate the mass in grams of one formula unit of sodium chloride.
1 formula unit NaCl 1 mol NaCl 58.44 g NaCl= 9.7 x 10-^23 g NaCl 6.022 x 10^23 formula unit NaCl 1 mol NaCl
d-How many ions of sodium does the can of salt contain?
12.6 mol NaCl 1 mol Na+^ 6.022 x 10^23 ions Na+^ = 7.59 x 10^24 ions Na+ 1 mol NaCl 1 mol Na+
e-How many moles of chloride ions does the can contain?
12.6 mol NaCl 1 mol Cl-^ = 12.6 mol Cl- 1 mol NaCl
f-How many grams of sodium does the can of salt contain?
12.6 mol NaCl 1 mol Na
22.99 g Na
= 289.67 g Na
1 mol NaCl 1 mol Na+
15. a-How many moles of ammonium sulfate are in 32.0 g of ammonium sulfate?
32.0 g (NH 4 ) 2 SO 4 1 mol (NH 4 ) 2 SO 4 = .242 mol (NH 4 ) 2 SO 4 132.17 g (NH 4 ) 2 SO 4
b-How many formula units of ammonium sulfate are there in 32.0 g of
ammonium sulfate?
32.0 g (NH 4 ) 2 SO 4 1 mol NH 4 ) 2 SO 4 6.022 x 10^23 formula units (NH 4 ) 2 SO 4 = 1.46 f.u.s (NH 4 ) 2 SO 4 132.17 g (NH 4 ) 2 SO 4 1 mol (NH 4 ) 2 SO 4
c-How many atoms of H are found in 32.0 g of ammonium sulfate?
32.0 g (NH 4 ) 2 SO 4 1 mol NH 4 ) 2 SO 4 8 mols H 6.022 x 10^23 atoms H = 1.17 X 10^24 atoms H 132.17 g (NH 4 ) 2 SO 4 1 mol (NH 4 ) 2 SO 4 1 mol H
d-How many grams of hydrogen are found in 32.0 g of ammonium sulfate?
32.0 g (NH 4 ) 2 SO 4 1 mol NH 4 ) 2 SO 4 8 mols H 1.01 g H = 1.94 g H 132.17 g (NH 4 ) 2 SO 4 1 mol (NH 4 ) 2 SO 4 1 mol H
