chapter 3 - amount of substance

Question 1

mole

Answer 1

one mole (mol) is the amount of substance that contains as many elemental particles as there are in 12g of carbon-12

Question 2

avogadro’s constant

Answer 2

6.022 x 1023 atoms

Question 3

empirical formulae

Answer 3

the simplest whole number ratio of elements within a substance * assume 100g total mass

Question 4

molecular formulae

Answer 4

shows the exact number of atoms of each element that is present within a substance

Question 5

stoichiometry

Answer 5

can be used to determine the moles/mass of a substance needed/formed during a reaction (mass = Mr mol)

Question 6

water of crystallisation

Answer 6

water contained within the ionic lattice of salt crystals; can be driven off by heating the salt crystals

Question 7

idea gas equation

Answer 7

pressure (Pa) x volume (m3) = moles x R (constant of 8.314) x temperature (K)

Question 8

concentration equation

Answer 8

moles = concentration x volume

Question 9

percentage yield calculation

Answer 9

percentage yield = (actual amount of product in mol / theoretical amount of product in mol) x 100

Question 10

atom economy calculation

Answer 10

atom economy = (Mr of desired product / Mr of all products) x 100