Mole concept and stoichiometry

Question 1

define the term relative atomic mass / weighted average of the isotopic masses.
Note: always quoted to 1 dp

no units

Answer 1

Relative Atomic Mass (Ar) of an element is the average mass of 1 atom of the element relative to 1/12th of 1 atom of 12C

Question 2

define the term isotopic mass

no units 1dp

Answer 2

Relative Isotopic Mass is the mass of 1 atom of the isotope relative to 1/12th the mass of 1 atom of 12C.

Question 3

define the term molecular mass

no units 1dp

For ionic compounds, use relative formula mass

Answer 3

Relative molecular mass (Mr) of a substance is the average mass of 1 molecule of the substance relative to 1/12th the mass of 1 atom of 12C

Question 4

Define relative formula mass

no units, 1dp

Answer 4

Relative formula mass (Mr) of a substanve is the average mass of 1 formula unit of the substance relative to 1/12th the mass of 1 atom of 12C

Question 5

Define the term mole in Avogradro constant

Answer 5

One mole of a substance contains exactly 6.02 x 10^23 (Avogadro costant) elementary entities

Question 6

units for molar mass

Relative molecular mass no units

Answer 6

gmol^-1

Question 7

Define emperical formula

Answer 7

Emperical formula is the simplest whole number ratio of the elements present in 1 molecule or formula unit of the compund

Question 8

define the term molecular formula

Answer 8

Molecular formula is the actual number of each of the different atoms present in the molecule