Name _________________________________________________
Period ___________________
Chapter 10: Chemical Quantities
Kaspriskie
HW#4:MOLE CONVERSIONS:
Once the molar mass of a compound is calculated, it can be used for mole conversions in the same way as
atomic mass, using the conversion factors: 1 mole = molar mass in grams
Convert 24.5g of carbon tetrafluoride to moles
STEP 1: Write the formula of carbon tetrafluoride which is covalent: CF4
STEP 2: Find the molar mass of CF4:
(1 x 12.01g/mol C) + (4 x 19 g/mol F) = 88.01 g/mol CF4
STEP 3: Use the molar mass as the conversion factor for dimensional analysis:
(round to two non-zero decimal places)
24.5g Cr(CN)3
1 mol CF4= 0.28 mol CF4
88.01 g CF4
Practice
1. Find the mass of 4.50 moles of diphosphorus pentoxide.
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2. How many moles is 250.0g of copper (II) sulfate?
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The smallest particle of a molecular compound is called a molecule. The smallest unit of an ionic crystal is
called a formula unit. Molar mass can be used to convert between molecules and formula units using the
conversion factors below.
1 mole = 6.02 x 1023 molecules (for molecular/covalent compounds)
1 mole = 6.02 x 1023 formula units (for ionic compounds)
3. How many formula units are in 110g of aluminum nitrate?
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HW#5:
MOLE CONVERSIONS
1. Write the formula for each compound below. Then determine its molar mass.
FORMULA
MOLAR MASS
calcium sulfate
aluminum cyanide
phosphorus triiodide
2. Use the molar masses you found in question 1 to make the following conversions:
a. Find the mass of 1.25moles of calcium sulfate.
b. Find the mass of 25 moles of oxygen.
c. How many molecules is 12.50g of phosphorus triiodide
d. Find how many atoms are in 10.0g of helium.
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