1-masala: Massasi 10,8 gr bo’lgan metal namunasida alyuminiy moddasining qanday miqdori bor? Yechish

Mol.Modda miqdori.
Molyar massa-bu modda massasining modda miqdoriga bo’lgan nisbatidir.
M= _{ }; m—massa, (gr) n-miqdor(mol), M-molyar massa (gr\mol)
1-masala: Massasi 10,8 gr bo’lgan metal namunasida alyuminiy moddasining qanday miqdori bor?
Yechish: M(Al)=27 gr\mol ekanligini bilamiz, bu masalani ishlashda ushbu formuladan foydalanib hisoblaymiz:
n (Al) = _{ } n=10,8\27=0,4 mol.
Demak,0,4 mol miqdorni tashkil etadi.
2-masala:Massasi 50,8 gr bo’lgan molekulyar yodda qancha struktura birlik bor?
Yechish: yodning molyar massasi J₂ 254gr\mol eknligini hisobga olib, formuladan foydalanib hisoblaymiz.
n(J₂) = _{ } n J₂=50,8\254=0,2 mol
N(J₂) = n(J₂)N_A N_J2=0,2·6,02·10²³=1,2·10²³
Demak, modda miqdori 0,2 mol, molekulalar soni esa 1,2·10²³ ga teng.
3-masala: 0,25 mol miqdordagi moddaning massasi 26,5 gr bo’lsa uning molyar massasini hisoblang?
Yechish:
formuladan foydalanib topamiz:

Demak, molyar massasi 106 gr\mol.
4-masala: 28,2 gr K₂O dan qancha massa potash olish mumkin.
Yechish: reaksiya tenglamasini yozamiz.
K₂O+CO₂=K₂CO₃
Hisoblaymiz: 28,2 x
94 138 x= 41,4 gr
Demak, 41,4 gr potash olish mumkin.
5-masala.3 mol H₄P₂O₇ va 5 mola H₂Cr₂O₇ tarkibidagi element atomlarining massa nisbatini hisoblanag?
Yechish : 3 mol pirofosfat kislotadagi atomlar sonini topib olamiz
3 mol —— x 5 mol —— x
H₄P₂O₇ H₂Cr₂O₇
1 mol —— 13 ta 1 mol —— 11 ta
x = 39 ta atom bor x = 55 ta atom bor
masala sharitiga binoan formulada ishtirok etgan atomlar sonini topib oldik endi ularning nisbatini hisoblaymiz.Bu uchun eng kichik sondan foydalanamiz.
39: 55
39 : 39
1 : 1,4
Demak javob 1:1,4 nisbatda bo’lar ekan.