Under mass conversions, connections between grams, moles and molecules are established.
The mole is the chemical unit for the amount of a substance and serves as the bridge that connects grams to molecules, atoms, formula units and ions.
Concept #1: Avogadro’s Number, Moles, Molecules & Atoms
The words atoms and ions are used when talking about a single element and the words molecules and formula units are used when talking about more than one element together.
Concept #2: Atoms to Moles to Grams
Example #1: Determine the mass (in grams) found in 7.28 x 1028 nitrogen atoms.
Concept #3: Molecules to Moles to Grams
Example #2: Determine the how many molecules of carbon dioxide, CO2, are found in 75.0 g CO2.
Practice: If the density of water is 1.00 g/mL at 25oC. Calculate the number of water molecules found in 1.50 x 103 µL of water.
Practice: Calculate the number of oxygen atoms found in 783.9 g in copper (II) sulfate pentahydrate, CuSO4 x 5 H2O.
Practice: The density of the sun is 1.41 g/cm3 and its volume is 1.41 x 1027 m3. How many hydrogen molecules are in the sun if we assume all the mass is hydrogen gas?
Practice: A cylindrical copper wire is used for the fences around a house. The copper wire has a diameter of 0.0750 in. How many copper atoms are found in 5.160 cm piece? The density of copper is 8.96 g/cm3. ( V = π x r2 x h )