The MoleUnit 6
Formula Mass
• Formula mass - (also called gram formula mass, molecular mass, formula weight, gram formula weight, molecular weight, gram molecular weight, molar mass, and molar weight): the mass of one mole of a compound, atom or ion.
So what is a mole???
http://ed.ted.com/lessons/daniel-dulek-how-big-is-a-mole-not-the-animal-the-other-one
Formula mass• Formula mass – the formula mass of any molecule,
formula unit, or ion is the sum of the average atomic masses of all the atoms represented in its formula.
• Molar mass- the molar mass of a substance is equal to the mass in grams of one mole, or 6.02 x 1023 particles of the substance.
• NOTE- These are 2 different terms but both are
calculated the same way. Know these terms, but usually we will refer to the molar mass as just that, or we may use “gfm” (the gram formula mass)
Formula MassExample: Find the formula mass of each of the
following:
arsenic trichloride: potassium sulfide:
Measuring MatterThere are three ways to measure matter: by
counting representative particles (typically molecules or formula units), by mass (in grams), or by volume (in liters for gases). The method used is usually chosen by the ease of each method and the information needed. Once a measurement has been made, it is possible to convert between the units for the other methods.
Measuring Matter
1 mole of a compound = formula mass (in grams)1 mole of an element = 6.02 x 1023 atoms of that
element 1 mole of a compound = 6.02 x 1023 representative particles 1 mole of a gas = 22.4 liters
The mole is the link between grams, the number of representative particles and liters!
For neutral compounds, the representative particle is either the molecule (covalent) or the formula unit (ionic). However, to simplify matters the term molecule is commonly used for both.
Mole Road Map
Mole Practice: One Step Conversions: Remember to show all work using dimensional analysis.
1. How many moles are in 18.0 grams of sugar (C6H12O6)?
Mole Practice: One Step Conversions: Remember to show all work using dimensional analysis.
2. What is the weight in grams of 4.50 moles of barium sulfide?
Mole Practice: One Step Conversions: Remember to show all work using dimensional analysis.
3. How many moles are in 3.90 x 1028
molecules of methane (CH4)?
Mole Practice: Multi Step Conversions:
7.How many formula units are in 198.5 grams of sodium chloride?
Mole Practice: Multi Step Conversions:
9. How many grams are in 3.21 x 1024
formula units of potassium hydroxide?
