Question

# Calculate the molar mass with proper steps of:

a)caustic soda
b)caustic Potash
c)baking soda
d)limestone
e)alum

Answer 1

a) Caustic  Soda.

Formula = NaOH

Atomic  mass of  elements:-

Na = 23

O  = 16

H = 1

Molar  mass  of  NaOH = 23 + 16 + 1 = 40 g/mol

Standard  Molar  mass = 39.997 g/mol

b) Caustic Potash:-

Formula  = KOH

Atomic  mass  of  elements;-

K = 39

O = 16

H  = 1

Molar  mass  of  KOH = 39 + 16 + 1 = 56 g/mol

Standard Molar  mass = 56.1056 g/mol

c) Baking  Soda:-

Formula = NaHCO₃

Atomic  mass  of  elements:-

Na = 23

H = 1

C = 12

O₃ = 16×3 = 48

Molar  mass  of NaHCO₃ = 23 + 1 + 12 + 48 = 84 g/mol

Standard molar  mass = 84.007 g/mol

d) Limestone

Formula  = CaCO₃

Atomic  mass  of  elements:-

Ca = 40

C = 12

O₃ = 48

Molar  mass  of  CaCO₃ = 40 + 12 + 48 = 100 g/mol

Standard molar  mass = 100.0869 g/mol

e) Alum (Potash Alum)

Formula = K₂SO₄.Al₂(SO₄)₃.24H₂O

Atomic  mass  of  elements:-

K₂ = 39×2 = 78

SO₄ = 32 + 16×4 = 96

Al₂ = 27×2 = 54

(SO₄)₃ = 96×3 = 288

24H₂O = 24 × 18 = 432

Molar mass  of  K₂SO₄.Al₂(SO₄)₃.24H₂O = 78+96+54+288+432

                                                                  = 948 g/mol