Relative Atomic and Molecular Masses

This video tutorial explains how to calculate relative molecular mass and relative formula mass. It begins with an introduction to the concepts, followed by detailed steps to calculate the relative molecular mass using examples like dichloroethane and diethylamine. The video also covers the calculation of relative formula mass for ionic compounds, using magnesium hydroxide as an example. By the end, viewers should be able to perform these calculations independently.

What is the primary difference between molecular and empirical formulas?

• Molecular formulas show the simplest ratio of elements.

• Molecular formulas are used for covalent compounds, while empirical formulas are used for ionic compounds.

• Empirical formulas show the actual number of atoms in a molecule.

• Empirical formulas are used for covalent compounds, while molecular formulas are used for ionic compounds.

Which of the following is true about relative molecular mass?

• It is the mass of a molecule compared to 1/12 of the mass of a carbon-12 atom.

• It is the mass of a molecule compared to the mass of a nitrogen atom.

• It is the mass of a molecule compared to the mass of a hydrogen atom.

• It is the mass of a molecule compared to the mass of an oxygen atom.

How do you calculate the relative molecular mass of dichloroethane?

• Divide the atomic masses of all atoms in the molecule.

• Multiply the atomic masses of all atoms in the molecule.

• Add the atomic masses of all atoms in the molecule.

• Subtract the atomic masses of all atoms in the molecule.

What is the relative molecular mass of diethylamine?

• 73.0

• 99.0

• 58.3

• 24.3

Which element in diethylamine has the highest relative atomic mass?

• Carbon

• Hydrogen

• Nitrogen

• Oxygen

What is the key difference in calculating relative formula mass compared to relative molecular mass?

• Relative formula mass uses the molecular formula.

• Relative formula mass uses the empirical formula.

• Relative formula mass uses the atomic formula.

• Relative formula mass uses the isotopic formula.

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

• Organic compounds

• Metallic compounds

• Ionic compounds

• Covalent compounds

What is the relative formula mass of magnesium hydroxide?

• 58.3

• 73.0

• 99.0

• 24.3

Which element in magnesium hydroxide has the highest relative atomic mass?

• Magnesium

• Hydrogen

• Oxygen

• Chlorine

How many oxygen atoms are present in the empirical formula of magnesium hydroxide?

• Four

• Three

• Two

• One