Chemistry Reference
In-Depth Information
3.
The smallest complete unit of water you could have is one
_______________.
4.
The smallest complete unit of table salt you could have is one
________________.
Find the formula mass of the following ionic compounds:
5.
CaI
2
_____________________
6. LiOH _____________________
7.
Cu(NO
3
)
2
_________________ 8. (NH
4
)
2
S ___________________
Find the molecular mass of each of the following molecular compounds:
9.
CO _______________________
10. NO
2
______________________
Lesson 5-6: Using Coefficients With Formulas
Up to this point in Chapter 5, we have been concerned with individual
formula units or molecules. In this lesson we will discuss how we represent
multiple formula units and molecules, in preparation for working with en-
tire chemical equations. You have probably had some experience working
with chemical equations before, possibly in a biology class, so this may not
be entirely new to you. What may be new to you is the level of understand-
ing that you will be expected to demonstrate, in a variety of ways, now that
you are studying chemistry.
When we want to represent multiple molecules or multiple formula
units, we simply write a large coefficient number before our chemical for-
mula. Let's illustrate this by looking at the formula for photosynthesis, which
you may remember from biology.
C
6
H
12
O
6
+ 6O
2
6CO
2
+ 6H
2
O
glucose + oxygen
carbon dioxide + water
You will notice that the first molecular formula, which represents glu-
cose, is not preceded by a coefficient. When this is the case, we understand
there to be only one molecule or formula unit involved in the balanced
chemical equation. There is a coefficient of “6” preceding each of the other
chemical formulas, indicating the six molecules of each of the other sub-
stances are involved in the chemical reaction. In summary, the reaction
shows us that one molecule of glucose will react with six molecules of di-
atomic oxygen, to form six molecules of carbon dioxide and six molecules
of water.
