Question

(b) Calculate percentage composition of various
elements in NaOH.
(At. Wt. of Na = 23, 0 = 16, H = 1)
(5)
Dof:
b.1
hat: h​

Answer 1

Explanation:

NaOH

Sodium Hydroxide

Na = 23 amu

OH = 16 + 1 = 17 amu

NaOH = Mass of sodium + mass of hydroxide

NaOH = 23 amu + 17 amu

NaOH = 40 amu

to calculate sodium percentage

mass of sodium / molecular mass × 100

{ 23 / 40 } × 100

cancel 100 and 40

you will get 10 and 4

{ 23 / 4 } × 10

cancel 10 and 4

you will get 5 and 2

{ 23 / 2 } × 5

115 / 2

57.5 %

percentage composition of oxygen

mass of oxygen / molecular mass × 100

{ 16 / 40 } × 100

{ 16 / 4 } × 10

{ 16 / 2 } × 5

80 / 2

40 %

percentage composition of hydrogen

mass of hydrogen / molecular mass × 100

{ 1 / 40 } × 100

{ 1 / 4 } × 10

{ 1 / 2 } × 5

2.5 %

57.5 % of Sodium (Na)

40 % of Oxygen (O)

2.5 % of Hydrogen (H)

TOTAL = 57.5% + 40% + 2.5% = 100%