Understanding the Concepts
Balance each of the following by adding coefficients:
Balance each of the following by adding coefficients:
If red spheres represent oxygen atoms and blue spheres represent nitrogen atoms
a. Write the formula for each of the reactants and products.
b. Write a balanced equation for the reaction.
If blue spheres represent nitrogen atoms and purple spheres represent iodine,
a. Write the formula for each of the reactants and products.
b. Write a balanced equation for the reaction.
If green spheres represent chlorine atoms, yellow-green spheres represent fluorine atoms, and white spheres
represent hydrogen atoms,
a. Write the formula for each of the reactants and products.
b. Write a balanced equation for the reaction.
If green spheres represent chlorine atoms and red spheres represent oxygen atoms
a. Write the formula for each of the reactants and products.
b. Write a balanced equation for the reaction.
If blue spheres represent nitrogen atoms and purple spheres represent iodine atoms
a. Write the formula for each of the reactants and products.
b. Write a balanced equation for the reaction.
Practice Problems
1. Balance the following chemical reaction:
P4(s) + O2(g)  P4O10(s)
a.
b.
c.
d.
P4(s) + O10(g)  P4O10(s)
2P4(s) + 4O2(g)  2P4O10(s)
P4(s) + 5O2(g)  P4O10(s)
P4(s) + 4O2(g)  P4O10(s)
2. Balance the following chemical reaction:
∆
C4H8(g) + O2(g) → CO2(g) + H2O(g)
∆
a. C4H8(g) + 3O2(g) → 4CO2(g) + 4H2O(g)
∆
b. C4H8(g) + 6O2(g) → 4CO2(g) + 4H2O(g)
∆
c. 2C4H8(g) + 6O2(g) → 4CO2(g) + 6H2O(g)
∆
d. 2C4H8(g) + 3O2(g) → 3CO2(g) + 3H2O(g)
Section 7.2 – Types of Reactions
Goal: Identify a reaction as a combination, decomposition, single replacement, double replacement, or
combustion reaction.
Summary
Understanding the Concepts
Identify each of the following as: combination, decomposition, single replacement, double replacement, or
combustion. (If it helps, use the equations you wrote for Understanding the Concepts for section 7.1. These are
the same reactions.)
Section 7.5 – Molar Mass and Calculations
Goal: Calculate the molar mass for a substance given its chemical formula; use molar mass to convert between
grams and moles.
Summary:
Calculating Molar Mass:
The molar mass of a compound is the sum of the molar mass of each element in it chemical formula multiplied
by it subscript in the formula. The molar masses of individual elements are found on the periodic table as the
atomic mass (the decimal number under the symbol).
Example:
Pinene, C10H16, which is found in pine tree sap and essential oils, has anti-inflammatory properties. Calculate
the molar mass for pinene.
Answer:
Using Molar Mass as a Conversion Factor
• The molar mass of an element is its mass in grams per mole equal numerically to its atomic mass.
• The molar mass of a compound is its mass in grams per mole equal numerically to the sum of the masses
of its elements.
• Molar mass is used as a conversion factor to convert between the moles and grams of a substance.
Example:
The frame of a bicycle contains 6500 g of aluminum. How many moles of aluminum are in the bicycle frame?
Answer:
\
Understanding the Concepts:
Using the models of the molecules (black = C, white = H, yellow =S, green = Cl) determine each of the
following for models of the compounds.
a. molecular formula
b. molar mass
c. number of moles in 10.0 g
Using the models of the molecules (black = C, white = H, yellow = S, Red = O) determine each of the
following for the models of the compounds
a. molecular formula
b. molar mass
c. number of moles in 10.0 g
Practice Problems:
29. Calculate the molar mass of the following:
a. FeSO4 _______ g/mol
b. C7H5NO3S _______ g/mol
c. (NH4)2CO3 _______ g/mol
d. O2 _______ g/mol
e. Fe(ClO4)3 _______ g/mol
30. Calculate the mass in grams for 1.50 moles K
a. 11.2 g
b. 39.1 g
c. 26.1 g
d. 58.6 g
e. 28.5 g
31. Calculate the mass in grams of 2.5 moles of C.
a. 24.0 g
b. 30.0 g
c. 4.80 g
d. 15.0 g
e. 16.2 g
32. Calculate the number of grams in 5.00 moles of C2H6O.
a. 212 g
b. 29.0 g
c. 460 g
d. 230 g
e. 46.1 g
33. Calculate the number of grams in 0.488 mole of C3 H6O3.
a. 29.0 g
b. 90.1 g
c. 44.0 g
d. 57.3 g
e. 185 g
Answer:
Calculation of theoretical yield:
Calculation of percent yield:
Understanding the Concepts
If green spheres represent chlorine atoms, yellow-green spheres represent fluorine atoms, and white spheres represent
hydrogen atoms, (7.1, 7.8)
a. Write a balanced equation for the reaction.
b. Identify the limiting reactant.
If blue spheres represent nitrogen atoms and white spheres represent hydrogen atoms, (7.1, 7.8)
a. Write a balanced equation.
b. Identify the diagram that shows the products.