Understanding Molecular and Formula Mass

The video tutorial explains the concepts of molecular mass and formula mass, highlighting that while their calculations are similar, their applications differ. Molecular mass is used for normal molecules, while formula mass is used for ionic compounds. The tutorial provides examples using water (H2O) for molecular mass and sodium chloride (NaCl) for formula mass. It also introduces the concept of gram molecular mass and gram formula mass, which are the respective masses expressed in grams.

What is the main difference in the use of molecular mass and formula mass?

• Molecular mass is used for ionic compounds, while formula mass is for molecules.

• Molecular mass is always larger than formula mass.

• Molecular mass is used for molecules, while formula mass is for ionic compounds.

• Both are used interchangeably for any compound.

How is the molecular mass of water (H2O) calculated?

• By dividing the atomic mass of oxygen by hydrogen.

• By adding the atomic masses of hydrogen and oxygen.

• By multiplying the atomic masses of hydrogen and oxygen.

• By subtracting the atomic mass of oxygen from hydrogen.

What does the term 'gram molecular mass' refer to?

• The molecular mass expressed in kilograms.

• The molecular mass expressed in grams.

• The formula mass expressed in grams.

• The formula mass expressed in kilograms.

For which type of compounds is the formula mass specifically used?

• Metallic compounds

• Organic compounds

• Ionic compounds

• Covalent compounds

Why are formula masses used for ionic compounds?

• Because they exist as ions in a crystal lattice.

• Because they are lighter than covalent compounds.

• Because they have discrete molecules.

• Because they are heavier than covalent compounds.

How is the formula mass of NaCl calculated?

• By dividing the atomic mass of sodium by chlorine.

• By adding the atomic masses of sodium and chlorine.

• By multiplying the atomic masses of sodium and chlorine.

• By subtracting the atomic mass of chlorine from sodium.

What is the atomic mass of sodium used in calculating the formula mass of NaCl?

• 16

• 35.5

• 23

• 58.5

What is the atomic mass of chlorine used in calculating the formula mass of NaCl?

• 35.5

• 23

• 58.5

• 16

What is the total formula mass of NaCl?

• 16

• 23

• 35.5

• 58.5

How is the gram formula mass of a compound expressed?

• In milligrams

• In liters

• In grams

• In kilograms