Formulae Equations 1

Question 1

What is the symbol for amount

of substance?

Answer 1

n

Question 2

What is the unit used to
measure amount of
substance?

Answer 2

Mole

Question 3

What does the Avogadro

constant represent?

Answer 3

The number of atoms per mole of the

carbon-12 isotope

Question 4

How to calculate the mass of 1

mole of the element?

Answer 4

Mass of 1 mole = relative atomic mass in

grams

Question 5

How to calculate moles when
mass and molar mass are
given?

Answer 5

Moles (mol) = mass (g) / molar mass (g mol -1)

Question 6

What is an empirical formula?

Answer 6

Simplest whole number ratio of atoms of

each element present in a compound

Question 7

How to calculate empirical

formula?

Answer 7

● Divide the amount of each element by its molar
mass
● Divide the answers by the smallest value obtained
● If there is a decimal, divide by a suitable number
to make it into a whole number

Question 8

State Avogadro’s law

Answer 8

Under the same temperature and
pressure, one mole of any gas would
occupy the same volume.

Question 9

How much volume does a gas
occupy, at room temperature
and pressure?

Answer 9

24 dm3

or 24000 cm3

Question 10

Define molar gas volume

Answer 10

The volume per mole of gas molecules

Question 11

Why do different gas particles

occupy the same volume?

Answer 11

The gas particles are very spread out,
hence individual differences has no
effect.

Question 12

How to calculate moles when

gas volume is given?

Answer 12

Moles (mol) = volume (dm3) / 24
Or
Moles (mol) = volume (cm3) / 24000

Question 13

What are the ideal ways in

which gases behave? (5)

Answer 13

● They are in continuous motion
● No intermolecular forces experienced
● Exert pressure when they collide with each other or
container
● No kinetic energy is lost in the collisions
● When temperature increases, kinetic energy of gases also
increase