Question

ꜱᴏʟᴠᴇ ᴛʜɪꜱ Qᴜᴇꜱᴛɪᴏɴ ☺☺​

Answer 1

Question :

Calculate the molecular masses (or molecular weights) of the following compounds.

(a) Copper sulphate crystals , CuSO₄.5H₂O

(b) (NH₄)₂SO₄ (Ammonium sulphate)

Given :

• Copper sulphate crystals , CuSO₄.5H₂O
• (Ammonium sulphate) (NH₄)₂SO₄

To find :

• The molecular mass of the given substances

Knowledge required :

Sum of the masses of all the individual atoms in a compound is known as Molecular weight (or) Molecular mass .

Solution :

(I) CuSO₄.5H₂O (Copper sulphate crystals)

Molecular mass of CuSO₄.5H₂O = Atomic mass of 'Cu' + Atomic mass of 'S' + 4(Atomic mass of 'O' )+ 5[ 2(Atomic mass of 'H' ) + Atomic mass of oxygen ]

➦ Molecular weight of CuSO₄.5H₂O = 64 + 32 + 4(16) + 5[ 2(1) + 16 ] amu

➦ Molecular weight of CuSO₄.5H₂O = 160 + 5(18) amu

➦ Molecular mass of CuSO₄.5H₂O = 160 + 90 = 250 amu

Hence , The molecular weight of CuSO₄.5H₂O = 250 amu

$\rule{300}{1}$

(II) (NH₄)₂SO₄ (Ammonium Sulphate)

Molecular weight of (NH₄)₂SO₄ = 2[ Atomic weight of 'N'] + 2[4(Atomic weight of 'H')] + Atomic weight of 'S' + 4(Atomic weight of 'O')

➦ Molecular Weight of (NH₄)₂SO₄ = 2(14) + 2[4(1)] + 32+ 4(16) amu

➦Molecular weight of (NH₄)₂SO₄ = 28 + 8 + 32 + 64 amu

➦ Molecular weight of (NH₄)₂SO₄ = 36 + 32 + 64 amu

➦ Molecular weight of (NH₄)₂SO₄ = 132 amu

Hence , The Molecular weight of (NH₄)₂SO₄ is 132 amu

$\rule{300}{1}$

Answer 2

first question solution ⬇️

->the molecular mass of CuSo4 × 5H20

=63×5+32+(16×4)+5(1×2+16)

=159×5 +90 =249.5 a.m.u

second question solution ⬇️

the molecular mass of (NH4)2SO4

=2(14+1×4)+32+(16×4)

=2×18+32+64

=36+32+65=132 a.m.u