Chapter Nine

Question 1

To what standard are masses compared to

Answer 1

The carbon-12 standard in which the given mass is 12

Question 2

Relative molecular mass (Mr)

Answer 2

The sum of the relative atomic masses of the atoms in the molecule

Question 3

Relative formula mass

Answer 3

The sum of the relative atomic masses of the elements in the formula

Question 4

What is the mole (n)

Answer 4

A quantity that allows chemists to measure accurate amounts of extremely small particles

Question 5

Avogrado’s number

Answer 5

• A constant
• 6.022 X 10^23
• NA

Question 6

What is one mol equal to

Answer 6

The same number of particles as there are atoms in exactly 12 grams of carbon-12

Question 7

n =

Answer 7

N / NA
N > number of particles
NA > avogrado’s number

Question 8

N =

Answer 8

n X NA
n > moles
NA > avogrado’s number

Question 9

Molar mass (M)

Answer 9

• The mass in grams of 1 mol of a particular element in a compound
• gmol^-1

Question 10

Symbol of the actual given particles (atoms, ions or molecules)

Answer 10

N

Question 11

Counting by weighing, n =

Answer 11

m / M
m > mass in grams
M > molar mass in gmol^-1

Question 12

Percentage composition

Answer 12

Proportion by mass of different elements in a compound

Question 13

Percentage composition formula

Answer 13

Mass of the element in 1 mol of the compound/molar mass of the compound X 100

Question 14

m is the

Answer 14

Mass in grams