mole concept

Question 1

define relative atomic mass

Answer 1

average mass of one atom of an element relative to 1/12 the mass of an atom of carbon-12

Question 2

name the standard atom

Answer 2

• carbon-12
• it is used as a basis of comparison for all other atomic mass measurements

Question 3

expression of atomic mass

Answer 3

• expressed in decimal form to 3 significant figures
• average out the stable isotopes of the element

Question 4

define relative molecular mass

Answer 4

average mass of one molecule to of that substance relative to 1/2 the mass of an atom of carbon-12

Question 5

expression of molecular mass

Answer 5

• add together the relative atomic masses (Ar) of the atoms in the formula
• the relative molecular mass is known as Mr

Question 6

common molecular masses

Answer 6

• water (H₂O): 18
• carbon dioxide (CO₂): 44
• carbon monoxide (CO): 28
• methanol (CH₃OH): 32
• ethanoic acid (CH₃COOH): 60