Metallurgiya asoslari

MASALALAR YEHCIMLARIDAN NAMUNALAR
1-misol. 300 K va 30562,5 Pa bosimda 7.1*10^-3 kg neon gazi berk idishda saqlanadi. Neon ga/.ini ideal gaz deb. uni benigan huroratda 103975 Pa gacha siqilsa. gazning termodinamik potensiallari (AF, AG, AS, AU, AH) qanday o'zgaradi?
Berilgan:
t = 27⁰C; T = 273+27=300K; m=7,1*10^-3kg
Mne = 0,0282 kg; bundan

P₁ = 30562,5 Pa; P₂ = 103975 Pa; R = 8,314 kJ/(mol*K)

Noma’lun: F=?. G=?, S=?, U=?, H=?
Yechish.1) G = n * RT • ln P₂/P₁ dan Gibbs energiyasi hisoblanadi.
G = 0,25*2,303*8,314*300 In = 1435*ln 3,4020
G = 1435*0,5318 = 763,5 kJ/ mol
2) T- const, izotermik jarayon entropiyasi S = n*R In P₂/P₁ for­mula asosida hisoblanadi:
. 103975
S = 0,25*8,314*2,303 In • = 4,7860 In 3,4020 =
= 4,7860*0,5318 = 2,4452 kJ/mol.
T=const, izotermik jarayonda sistemaning entalpiya o'zgarish qiy­mati Gibbs energiyzisi qiymatidan aniqlanadi:
G = H - T S dan H = G +T S bo'ladi
H = 763,5 + 300-2,4452 * 1496,06 kJ/mol
T=const va V = const bo'lganda sistema ichki energiyasining o'zgarish qiymati uning bajargan ish qiymatiga teng bo'ladi.
U * A bo’lgani uchun U = - 2107, 867 J/mol.
T = const bo'lganda sistemaning Gelmgols energiyasining qiymati
F = U — T S yoki G = F + P V formulalardan hisoblanadi, aga
F = U - T S asosida ishlansa;
F = -2107,867 – 300*2,4452 = - 2841,427 J/mol kelib chiqadi.
2-misol. reaksiya uchun
izobar potensial G⁰ ning standart o'zganshini hisoblang. Bunda jadval qiymatlari H₂₉₈va S₂₉₈ dan foydalaniladi.
Yechish: Ma’lumotnomadan reaksiyada qatnashuvchi moddalarning entalpiya va entropiya standart qiymatlari topiladi. Standart sharoit uchun:
G⁰ = H₀-T S⁰
H⁰_reaks = 2 H²CO₂ - H⁰ H₂O_(s) - H⁰C₂H₂ =
= 2 (-393,51) -285,84 – 226,75 = - 1299,61 kJ/mol,
S⁰_reaks. = 2S⁰CO₂ + S⁰H20_(s) – S⁰C₂H₂ – 2,5 S⁰O₂ =
= 2*213,6 + 69,96 - 200,8 - 2,5*205,03 = -216,21 J/ mol*K
yoki
S⁰ = -0,2162kJ/(mol*K)
G⁰₂₉₈ = -1299,61 (-0,2162*298) = -1235,19 kJ/mol.
3-misol. Agar 1000 K haroratda G° C₆H₆ = 402,2 kJ/mol va G⁰ C₂H₄ = 114 kJ/ mol ga teng bo‘lsa, C₆H₁₂ 3C₂H₄ reaksiya shu haroratda qaysi tomonga boradi?