General Chemistry Principles, Patterns, and Applications, 2011

23.
a. 27.6 mg C and 1.98 mg H
b. 5.2 mg O
c. 15%
d. C 7 H 6 O
e. C 7 H 6 O
25. hydrocyanic acid, HCN
27. To two decimal places, the values are:
a. 273.23 amu
b. 69.62 amu
c. 157.01 amu
d. 82.14 amu
e. 98.00 amu
f. 45.08 amu
29. Urea
[1] Do not assume that the “missing” mass is always due to oxygen. It could be any other element.
[2] Other elements, such as metals, can be determined by other methods.
3.3 Chemical Equations
L E A R N I N G O B JE C T I V E S
1. To describe a chemical reaction.
2. To calculate the quantities of compounds produced or consumed in a chemical reaction.
As shown in Figure 3.7 "An Ammonium Dichromate Volcano: Change during a Chemical Reaction", applying a small
amount of heat to a pile of orange ammonium dichromate powder results in a vigorous reaction known as the
ammonium dichromate volcano. Heat, light, and gas are produced as a large pile of fluffy green chromium(III) oxide
forms. We can describe this reaction with a chemical equation, an expression that gives the identities and quantities
of the substances in a chemical reaction. Chemical formulas and other symbols are used to indicate the starting
material(s), orreactant(s), which by convention are written on the left side of the equation, and the final
compound(s), or product(s), which are written on the right. An arrow points from the reactant to the products:
Saylor URL: http://www.saylor.org/books
Saylor.org
222