Percentage Composition (Write On Paper If Needed)

Question 1

Where can you find equations in a test/exam?

Answer 1

The front of the data book.

Question 2

How to calculate % by mass?

Answer 2

% by mass= mass of element x100
GFM

M x100/GFM
(Big number into the small number)

Question 3

Where do you find atomic mass in a test/exam?

Answer 3

Atomic mass is found on page 7 of data book.

Question 4

How do you find the mass in a % equation?

Answer 4

The mass is always the first number of the GFM E.g. Na= 2x23= 46 m=46

Question 5

What is the % of sodium sulphate Na2SO4
(Write on paper if needed)

Answer 5

What is the % of sodium sulphate Na2SO4

M=46

GFM=
Na= 2x23= 46
S= 1x32=32
O= 4x16=64
=142

M x100
GFM

46 x100
142
=32%

Question 6

What is the % of magnesium in magnesium nitrate Mg(NO3)2
(Write on paper if needed)

Answer 6

What is the % of magnesium in magnesium nitrate Mg(NO3)2

M= 24.5

GFM=
Mg= 1x24.5= 24.5
N= 2x14= 28
O= 6x16= 96
=148.5

M x100
GFM

24.5 x100
148.5
=17%