Chapter 7: Mole concept and stoichiometry

Question 1

Define relative atomic mass

Answer 1

The relative atomic mass (Ar) of an element is the average mass of one atom of that element relative to 1/12 the mass of an atom of carbon-12.

Question 2

Define relative molecular mass

Answer 2

The relative molecular mass (Mr) of a molecular substance is the average mass of one molecule of that substance relative to 1/12 the mass of an atom of carbon-12.

Question 3

Define relative formula mass

Answer 3

The relative formula mass (Mr) of an ionic compound is the average mass of one unit of that relative compound relative to 1/12 the mass of an atom of carbon-12.

Question 4

Define molar mass

Answer 4

One mole of any substance has a mass equal to its relative atomic mass (Ar), relative molecular mass or relative formula mass (Mr) in grams. This mass is the molar mass of the substance.

Question 5

Define one mole

Answer 5

One mole of any substance (s,l,g) will always contain 6.02 x 10^23 particles of the substance. The particles can be atoms, molecules, ions and even sub-atomic molecules such as electrons.

Question 6

What is the unit for molar mass

Answer 6

g/mol

Question 7

What is empirical formula

Answer 7

The simplest ratio of elements in a compound is called its empirical formula.