Chapter 1.2 - Stoichiometric Relationships - The mole concept

Question 1

What is a Mole?

Answer 1

a fixed number of particles and refers to the amount, n, of substance

Question 2

Avogadro’s constant (Na)

Answer 2

6.02 x 10^23

Question 3

Molar mass

Answer 3

mass of 1 mole of a substance (g mol-1)

Question 4

Mole calculations - Avogadros constant, number of particles and moles

Answer 4

number of particles ÷ avogadros constant -> moles
moles x avogadros constant -> number of particles

Question 5

Mole calculations - moles, mass and molar mass

Answer 5

moles x molar mass -> mass
mass ÷ molar mass -> moles

Question 6

Isotopes

Answer 6

Atoms of the same element which have same number of protons

Question 7

Relative abundance

Answer 7

Measure of percentage of isotopes present in element

Question 8

Relative atomic mass (Ar)

Answer 8

weighted average of the atomic masses of its isotopes and their relative abundances
Relative because compared to 1 atom of carbon-12 (12C) which is 12 units

Question 9

Relative molecular mass (Mr)

Answer 9

Combining individuals Ar values of atoms in molecule or formula unit

Question 10

Empirical formula

Answer 10

simplest whole number ratio of atoms or amount (in mol) of each element present in a compound

Question 11

Molecular Formula

Answer 11

the actual number of atoms or amount (in mol) of elements in one structural unit or one mole of the compound