SAT Subject Test Chemistry
PART 2
REVIEW OF MAJOR TOPICS
CHAPTER 6
Stoichiometry (Chemical Calculations) and the Mole Concept
MOLE RELATIONSHIPS
Because the mole is used often in chemistry to quantify the number of atoms, molecules, and several other items, it is important to know the relationships that exist and how to move from one to another. The following summarizes a number of these relationships:
TIP
Know how to use these mole relationships. They will be needed to do stoichiometry problems.
When dealing with elements—
Moles of an element × molar mass (atomic) = mass of the element
Mass of an element/molar mass (atomic) = moles of the element
When dealing with compounds—
Moles of a compound × molar mass (molecular) = mass of the compound
Mass of a compound/molar mass (molecular) = moles of the compound
When dealing with the molecules of a compound—
Moles of molecules × 6.02 × 1023 = number of molecules
Number of molecules/6.02 × 1023 = moles of molecules
When dealing with the atoms of elements—
Moles of atoms × 6.02 × 1023 = number of atoms
Number of atoms/6.02 × 1023 = moles of atoms