Question

what is the molecular weight of
a.H2SO4
b.H3PO4
c.KMnO4
d.K2Cr2O7
e.H2C2O4.2H2O​

Answer 1

Answer:

a.The molar mass of hydrogen is 1

Molar mass of sulphur (S) is 32

Molar mass of oxygen (O) is 16

Now ,

2(1)+32+4(16) = 98

Molar mass of sulphuric acid i.e. H ₂SO₄ is 98.

b. Molecular mass (u) of Phosphoric Acid (H ₃PO₄) = 3 x  mass of H atoms + mass of phosphorous atom + 4 x mass of oxygen atom

 =3+31+64=98u

c.Molecular Mass of KMnO₄ = Atomic mass of potassium + atomic mass of manganese + 4 (atomic mass of oxygen)

= 1(39u) + 1(55u) + 4(16u) = 39u + 55u + 64u = 158u

d. Potassium Dichromate -- K₂Cr₂O₇

  Atomic mass of K=39u

Atomic mass of Cr=52u

Atomic mass of O=16u

Molecular mass of K₂Cr₂O₇ is the sum of all the atomic masses of the elements present in the compound.

=2x39+2x52+7x16

=78+104+112

=294u

e. The molar mass of oxalic acid dihydrate (H₂C₂O₄.₂H₂O)

H₂C₂O₄ = 2 + (2 * 12) + (4 * 16)

₂H₂O = 2 * 18

Molar mass = sum of the above=126