Chemistry Regents
Mr. Markic
Page 1 of 6
Chapter 10 - Chemical Quantities
Gram Formula Mass
 Unit of molar mass is ________________
 Often called ________________
 Use ________________from the Periodic Table
 Sum of the atomic masses for all atoms in a compound
Sample Problem
• What is the molar mass of hydrogen peroxide (H2O2)?
Practice Problems
• What is the mass of Sodium Hydrogen Carbonate?
•
What is the molar mass of MgSO4 • 7H2O
The Mole: A Measurement of Matter
• Measurements are taken by one of the three methods: by ________, by ___________, and by
____________________.
Converting Moles to Number of Particles
 A mole of a substance contains Avogadro’s number of particles, or ______________________
Sample Problem
• Propane is a gas used for cooking and heating. How many atoms are in 2.12 mol propane
(C3H8)?
Practice Problems
• How many atoms are in 1.14 mol SO3?
•
How many moles are in 4.65 x 1024 molecules of NO2?
Chemistry Regents
Mr. Markic
Page 2 of 6
Mole – Mass Relationship (_______________)
• Use the molar mass of an element or a compound to convert between the mass of a substance
and the moles of a substance
Sample Problem
• What is the mass of 9.45 mol of Al2O3?
Practice Problems
• Find the mass in grams of 4.52 x 10-3 mol C20H42
•
Calculate the mass, in grams, of 2.50 mol of Iron (II) hydroxide.
•
How many moles of Fe2O3 are contained in 92.2 grams?
•
Calculate the number of moles in 75.0 g of dinitrogen trioxide.
•
Find the number of moles in 0.370 g of boron.
Chemistry Regents
Mr. Markic
Page 3 of 6
The Mole-Volume Relationship
• At STP (________________________________________________), 1 mol or 6.02 x 1023
representative particles, of any gas occupies a volume of ________________L
•
________________ = ________________
•
Standard Pressure = ________________, ________________
•
Standard Temperature = ________________
Sample Problem
• Sulfur dioxide (SO2) is a gas produced by burning of coal. It is an air pollutant and one of the
causes of acid rain. Determine the volume, in liters, of 0.60 mol SO2 gas at STP.
Practice Problems
• What is the volume of these gases at STP?
a) 3.20 x 10-3 mol CO2
•
At STP, what volume do these gases occupy?
a) 1.25 mol He
b) 3.70 mol N2
b) 0.335 mol C2H6
Calculating Molar Mass from Density
• Density of a gas is measured in (________________)
Sample Problem
The density of a gaseous compound containing carbon and oxygen is found to be 1.964 g/L at STP.
What is the molar mass of the compound?
Practice Problems
A gaseous compound composed of sulfur and oxygen, which is linked to the formation of acid rain,
has a density of 3.58 g/L at STP. What is the molar mass of this gas?
Chemistry Regents
Mr. Markic
Page 4 of 6
What is the density of krypton gas at STP?
Percent Composition of a Compound
• The relative amounts of the elements in a compound
• Found in ________________
Sample Problem
• Propane (C3H8), the fuel commonly used in gas grills, is one of the compounds obtained from
petroleum. Calculate the percent composition of propane.
Practice Problems
• A compound is formed when 9.03 g Mg combines completely with 3.48 g N. What is the percent
composition of this compound?
•
When a 14.2 g sample of mercury (II) oxide is decomposed into its elements by heating, 13.2 g Hg
is obtained. What is the percent composition of the compound?
Sample Problem
• When a 13.60 g sample of a compound containing only magnesium and oxygen is
decomposed, 5.40 g of oxygen is obtained. What is the percent composition of this
compound?
Practice Problems
• Calculate the percent composition of these compounds:
a) Ethane (C2H6)
b) Sodium Hydrogen Sulfate (NaHSO4)
Chemistry Regents
Mr. Markic
Page 5 of 6
Calculate the percent nitrogen in these common fertilizers
a) NH3
b) NH4NO3
Determining the Empirical Formula of a Compound
• The empirical formula of a compound shows the ______________ whole-number __________of
the atoms in the compound
Sample Problem
• A compound is analyzed found to contain 25.9% nitrogen and 74.1% oxygen. What is the
empirical formula of this compound?
Practice Problems
• Calculate the empirical formula of each compound:
a) 94.1% O, 5.9% H
b) 67.6% Hg, 10.8 % S, 21.6% O
•
1,6-diaminohexane is used to make nylon. What is the empirical formula of this compound if it is
62.1% C, 13.8% H, 24.1% N?
Finding the Molecular Formula of a Compound
• The molecular formula of a compound is either the same as its experimentally determined empirical
formula, or it is a simple whole-number multiple of its empirical formula
Sample Problem
• Calculate the molecular formula of a compound whose molar mass is 60.0 g/mol and empirical
formula is CH4N.
Chemistry Regents
Mr. Markic
Page 6 of 6
Practice Problems
• Find the molecular formula of ethylene glycol (CH3O), which is used as antifreeze. The molar mass
is 62 g/mol
•
Which pair of molecules has the same empirical formula?
a) C2H4O2, C6H12O6
b) NaCrO4, Na2Cr2O7
Writing and Using Mole Ratios
• Mole – Mole Calculations
• Constructing mole ratios from balanced chemical equations
Sample Problem
N2 + 3H2 → 2NH3
How many moles of ammonia are produced when 0.60 mol of nitrogen reacts with hydrogen?
Practice Problems
4Al + 3O2 → 2Al2O3
•
How may moles of aluminum are needed to form 3.7 mol of Al2O3
•
How many moles of oxygen are required to react completely with 14.8 mol Al?
•
How many moles of Al2O3 are formed when 0.78 mol O2 reacts with aluminum?
5C + 2SO2 → CS2 + 4CO
•
How many moles of CS2 form when 2.7 mol of C reacts?
•
How many moles of carbon are needed to react with 5.44 mol SO 2?