Organik va fizikaviy kimyo kafedrasi

1- masala. Quyidagi moddalarning nisbiy molekulyar massalarini hisoblang: Ca(OH)₂, Na₂SO₄, Ba(NO₃)₂, H₃PO₄.

Yechish. Moddalarning nisbiy molekulyar massalarini hisoblaymiz:

Mr(Ca(OH)₂) =Ar(Ca)+2Ar(O)+2Ar(H) =40 + 2x16 + 2x1 =40 + 32 + 2=74 m.a.b.

Mr(Na₂SO₄)=2Ar(Na)+Ar(S)+4Ar(O)=2x23+ 32 + 4x16=46 + 32 + 64=142 m.a.b.

Mr(Ba(NO₃)₂)=Ar(Ba)+2Ar(N)+6Ar(O)=137+2x14+6x16=137+28+ 96=261m.a.b.

Mr(H₃PO₄)= 3Ar(H) + Ar(P) + 4Ar(O) = 3x1 + 31 + 4x16 = 3 + 31 + 64 = 98

2 – masala. 49 g sulfat kislota necha molni tashkil qilishini hisoblang.

Yechish. 1- usul. Moddaning nisbiy molekulyar massasini hisoblaymiz:

Mr(H₂SO₄)= 2Ar(H) + Ar(S) + 4Ar(O) = 2x1 + 32 + 4x16 = 2 + 32 + 64 = 98 m.a.b.

tenglamadan foydalanib 49 g sulfat kislota necha molni tashkil qilishini hisoblaymiz: mol

2 – usul. Masalani proporsiya usulida ham yechish mumkin.

Dastlab sulfat kislotaning nisbiy molekulyar massasini hisoblaymiz:

Mr(H₂SO₄)= 2Ar(H) + Ar(S) + 4Ar(O) = 2x1 + 32 + 4x16 =

2 + 32 + 64 = 98 m.a.b.

98 g H₂SO₄ ———— 1 mol

49 g H₂SO₄ ———— x mol x=49g∙1mol/98g = 0,5 mol.

3 – masala. Gramm – mol massasi 80 g bo’lgan CuO ning 0,3 mol miqdori qancha gramm bo’ladi?

Dastlab sulfat kislotaning nisbiy molekulyar massasini hisoblaymiz:

Mr(CuO)= Ar(Cu) + Ar(O) = 64 + 16 = 80 m.a.b. yoki gramm/mol

tenglamadan foydalanib mis oksidining massasini (m) hisoblaymiz:

m= н ∙ M = 0,3 mol ∙ 80 g/mol =24 gramm.

4 - masala. Natriy atomining o’rtacha mutlaq (absolyut) masasini hisoblang.

Yechish. m _(Na) = 22,990 • 1,66057 • 10^-24 = 38,177 • 10^-24 g.