Molar Mass and Mole Calculations

The video tutorial covers various mole calculations, including finding the number of molecules in a given number of moles, converting moles to mass using the periodic table, and calculating the molar mass of ions and compounds. It emphasizes setting up proportions to cancel units and switch to desired units, such as grams or molecules. The tutorial also explains the impact of charges on ions and the negligible mass of electrons in these calculations.

What is the first step in setting up a proportion for mole calculations?

• Identify the number of molecules.

• Determine the units you have and want.

• Find the molar mass on the periodic table.

• Calculate the number of atoms.

How many molecules are in 22.5 moles of nitrogen trihydride?

• 1.35 x 10^25 molecules

• 6.02 x 10^23 molecules

• 2.5 x 10^24 molecules

• 3.0 x 10^22 molecules

What is the molar mass of oxygen used in calculations?

• 14.01 grams

• 18.00 grams

• 12.01 grams

• 16.00 grams

When converting moles to grams, what information is essential from the periodic table?

• Molar mass

• Valence electrons

• Atomic number

• Electron configuration

What is the mass of one mole of ammonium ions (NH4+)?

• 22.05 grams

• 18.05 grams

• 20.05 grams

• 16.05 grams

How does the charge of an ion affect its molar mass?

• It doubles the molar mass.

• It halves the molar mass.

• It does not affect the molar mass.

• It adds 1 gram to the molar mass.

What is the mass of 0.86 moles of sulfate (SO4^2-)?

• 75 grams

• 100 grams

• 96 grams

• 83 grams

What is the mass of one atom of vanadium?

• 8.46 x 10^-23 grams

• 1.00 x 10^-22 grams

• 5.00 x 10^-24 grams

• 2.00 x 10^-23 grams

How do you calculate the mass of a compound like Fe2O3?

• Subtract the atomic masses of all elements.

• Add the molar masses of all elements in the compound.

• Multiply the atomic masses of all elements.

• Add the atomic numbers of all elements.

What is the mass of 0.655 moles of iron(III) oxide (Fe2O3)?

• 120 grams

• 95 grams

• 105 grams

• 150 grams