Cơ sở lý thuyết các quá trình hóa học trần thị đà

\
TRAN THI DA
DANG TRAN PHAC

a sa

bhuLfei:

CAC PHAN UNG
HOA HOC

m


TRAN TH| BA - BANG TRAN PHACH

ctf

self u

nnjYifr

ifolGWOAwQC.
( Tdi ban Ian thti nhat )

NHA XUAT BAN GIAO BUC


04 - 2006 / CXB / 159 - 1860/ GD

Ma so: 7K 589T 6

DAI


Ldi m m
Hod hoc ngay nay dang 6 uao tho' i ki phat trien manh me . Cac
uan de li thuyet dupe hoan thien . mo rong ua doi mdi . Cac thanh
tuu trong nghien cdu ua trong san xuat ngay cang da dang , phong
phu . Cac phuong phdp thac nghiem ngay cang tinh ui ua hdu hieu
da lam cho kho tang kien thdc hoa hoc ngay cang do so hon .
Trade boi canh do , ca ngadi hoc , ngadi day ua ngadi nghien cdu
cang phai nam udng cd sd li thuyet cua nhdng bien doi hod hoc ,
trade het 1a cua cac phan dng hod hoc .

Cuon sach nay nham cung cap nhdng kien thdc ue

:

Co so cua Nhiet dong lac hoc hod hoc .
Co so cua Dong hod hoc .
Moi lien he gida thanh phan , cdu tao ua tinh chat cua
chat tan , dung moi ua dung dich , dac biet 1a nhdng hieu
biet moi ue dung moi long uc,i sa sonuat hod .

Li thuyet axit - bazo ua phan dng axit - bazo, dac biet
la uiec phan biet lac axit - bazo trong nadc ua trong dung
moi khac udi nadc . Do axit trong ua ngoai pham ui
thang pH .

Phan dng oxi hod - khd , cO che phan dng , lac

oxi hod - khd . dac biet la nhdng dng dung cua phan dng oxi
hod - khd trong cong nghiep hod chat , trong linh uitc moi
trao' ng ua trong cuoc song thadng ngay .
Cac hoi dung tren dape uiet 6 hai mdc do khac nhau : mdc do
co ban ua mdc do nang cao . Cac muc co ghi dau * la nhdng kien
thdc nang cao , md rong ua di sau udo co sd li thuyet cac phan dng
hod hoc .
Bang uiec ket hop hai yeu cdu co ban ua nang cao , chung toi hi
uong rang cuon sach nay khong nhdng la giao trinh giang day cho
sinh uien cac nganh co hoc mon Hod hoc md con doi udi ca sinh
3


uien cac nam cud' i ua hoc men cao hoc cac trudng Dai hoc ua Cao
ddng thuoc chuyen nganh Hod hoc. Dong thdi cuon sach con la tdi
lieu tham khao cho giao men Trung hoc pho thong , giang men hod
hoc cac trudng Dai hoc , Cao dang ua cac can bo nghien cUu

hod hoc .

Sach gom chin chuctng , dupe phan cong bien soan nhu sau

:

PGS Dang Tran Phach : tie chuang I den chuang V .
PGS Tran Thi Da : tu chuang VI den chuang IX ..

Cuon sach chdc con thieu sot . Cac tac gia chan thanh cam an
nhdng y kien dong gop ua phe binh cua cac dong nghiep ua cac
ban doc.

Cac tac gia

4


MUC LUC
Lai noi dau
Muc luc

3
5

Chtrong 1
NGUY&N LI THCfNIHAT CUA NHIET B0NG LUC HOC
1.1. Mot so khai niem va dinh nghla ccf ban
9
trong nhiet dong life hoc
9
1.1.1. He nhietdong
1.1. 2 .Trang thai cua mot he. Thong so trang thai
10
10
1.1.3. Bien doi cua mot he
10
1.1 . 4. Ham trang thai
1.1.5 Cong va nhiet
10
thijf
li

nhat cua nhiet dong life hoc
1.2. Nguyen
14
1.2.1. Phat bieu nguyen III
15
1.2.2. Ham trang thai noi nang U
18
1.2.3 . Ham trang thai entanpi H
18
1.2.4. Nhiet dung
1.3. Ap dung nguyen li thuf nhat cua nhiet
dong life hoc vao Hoa hoc
22
1.3.1. Hieu irng nhiet cua phan Crng hoa hoc 22
1.3 . 2. Phirong phap tinh hieu Png nhiet
24
1.3. 3. Sir phu thuoc cua hieu irng nhiet vao nhiet
dp va ap suat
41
Bai tap
44

Chirong 2

NGUYEN Lf THLfHAI VA NGUYEN LI THU BA
1

CUA NHIET BONG LIJC HOC
2.1 . Nguyen li thuf hai cua nhiet dong life hoc48
2.1.1. Bong co nhiet

48
2.1. 2. Phatbieu nguyen li II
49
3
Chu
2.1. .
trinh Carnot
50
2.1.4. Bjnh li Carnot
52
2.1.5. Entropi. Chieu hirdng va gidi han cua bien
doi trong he co lap
53
2.1.6 . Tinh bien thien entropi
55
2.2. Nguyen li thuf ba cua nhiet dong life
hoc tinh entropi tuyet doi cua mot chat
58

2.2.1. Nguyen li thO ba cua nhiet dong luc hoc 58
2.2.2. Cach tinh entropi tuyet doi cua mot chat 58
2.2.3 . Tinh bien thien entropi trong mot phan ung
60
hoa hoc
2.3. Entropi va xac suat nhiet dong
61
2.4 . Chieu cua nhifng bien doi trong he
62
khong co lap
62

2.4.1. Cac ham trang thai U, H, S, F, G
64
2.4 . 2. Bieu kien tu didn bien cua mot he
2.4.3. Kha nang dien bien cua mot
65
phan irng hoa hoc
72
2.5. Hoa the
:4
2.5.1. Cac dai lupng mol phan
72
73
2.5 . 2. Hoa the
75
2.5.3. Hoa the ciia cac khi
2.5 . 4. Hoa the cua cac chat long
76
Bai tap
79
Chirong 3

CAN BANG PHA
3.1 . Mot so khai niem
3.2 . Bieu kien tong quat ve can blng
trong he d| the
3.3. Quy tic pha
3.4. Can bang pha trong he mot cau tuf
3.4 . 1. Nhurng he thirc ve can bang
trong nhurng sir chuyen pha loai mot
3.4. 2. Gian do pha cua nude

Bai tap

84
85
86
87

88
91
93

Chwong 4

CAN BANG HOA HOC
4.1 < Bieu kien tong quat cua
can bang hoa hoc
4.2. Khao sat d'mh lifcfng ve
can bang hoa hoc
4.2.1. Hang so can bang
4.2. 2. Can bang hoa hoc dong the
4.2.3. Can bang hoa hoc di the

95

96
96
97
103
5

4.3. Quan he gitfa bien thien entanpi ty do
104
va hing so can bing
107
4.4. Sifchuyen dich can bang

4.4 . 1. Anh hudng cua nniet do .
Djnh luat Van t Hopp
'

108

4.4 . 2 . Anh hucfng cua ap suat .
Dinh luat Le chalelier

112
116

Baitap

Chirong 5

CO SO CUA DONG HOA HOC
5.1. Mot so khai niem va dinh nghTa cd ban 120
5.1.1. Phan ung dong the va phan ung dj the 120
120
5.1. 2. Toe do phan ifng
5.2. Cac yeu to anh hircrng
den toe do phan ting

123

5.2.1. Anh hudng cua nong do . Khai niem ve bac
123
phan Ung va phan tir so
5.2. 2 . Anh hudng cua nhiet dp - Nang luong hoat
dong hoa
126
5.3. Sy tich phan cac phirong trinh dong hoc
131
cua cac phan ufng ddn gian
5.3 . 1 . Phan Crng bac khong
132
5.3.2 . Phan Crng bac nhat
133
5.3.3. Phan ling bac hai
135
5.3 . 4 . Phan irng bac n
139
5.4. Phudng phap xac dinh bac phan irng 139
5.4 . 1. Phuong phap dpa vao viec
do chu ki ban huy
139
5.4.2. Phuong phap vi phan
141
5.4 .3. Phuong phap tich phan
141
5.4 . 4 . Phuong phap co lap cua Ostwald
143

5.4.5 . Phuong phap dung toe do dau V
144
5.5. Cac phan img phife tap
145
5.5. 1. Cac phan irng thuan nghjch
145 .
5.5 . 2 . Cac phan irng noi tiep
147
5.5.3. Cac phan irng song song
150
5.6. Cd che phan irng
152
5.6.1. Khai niem ve cdche phan irng
152
5.6 . 2. Dinh luat ve toe do va co che phan irng 153
5.6.3 . Cac chat trung gian co kha nang phan irng .
Nguyen li Bodenstein
156
0

6

5.6 . 4 . Phan irng day chuyen
5.7. Phan irng quang hoa hoc
5.8. Xiic tac
5.8 . 1. Cac dinh nghTa
5.8 . 2. Xiic tac dong the
5.8. 3. Xiic tac dj the
5.8.4. Xuc tac enzim hay xuc tac men
5.9. Thuyet va cham hoat dong

5.10. Thuyet phirc chat hoat dong
Baitap

158
163
167
167
168
173
176
182
184
189

Chirong 6
DUNG DICH
6.1 . Khai niem chung ve dung dich
198
6.1.1. Mot so dinh nghTa
198
203
6.1.2 . Nong do dung dich
6.2. Dung moi long
206
6.2.1. Cau true chat long
206
6.2. 2. Phan loai dung moi
208
6.3 .* Sysonvat hoa
213

6.3.1. Khai niem sonvat hoa
215
6.3.2 . Lyc giura cac phan tir
216
trong dung dich va sy sonvat hoa
6.4 . Dung djeh long
222
6.4 . 1. Anh hudng cua cac yeu to
entanpi va entropi den qua trinh hoa tan
222
6.4 . 2. Dung dich khi - long
224
6.4.3. Dung djeh long - long
227
6.4.4 . Dung djeh ran long
229
231
6.4 .5 . Dinh luat phan bo . Sy chiet
6.5. Dung djeh chufa chat tan khong dien li,
khong bay hdi
232
6.5 .1. Sy giam ap suat hoi bao hoa
cua dung dich
232
6.5. 2. Do tang nhiet do soi va - do giam nhiet do
dong dac cua dung dich
234

236
6.5.3 . Ap suat thamthau

6.5 . 4. Xac dinh phan tir khoi cua chat tan
238
6.6. Dung dich chat dien li
239
6.6.1. Cac “ tinh chat nong do " cua dung dich
chat dien li
239
6.6 . 2. Sy phan li cua cac chat trong


a -* '

dung dich nude
6.6 . 3 . Do dien li . Hang so dien li
6.6 . 4. Dung dich chat dien ii manh
6.7. Dung dich chat dien li it tan
6.7 . 1.Tich so tan
6.7 . 2 . Tich so tan va sir ket tua
6.7 . 3 . Tich so tan va sir hoa tan
cac keUiia hop chat ion
6.8. Can bdng cua cac ion phirc
6.8 . 1 . Sir hinh thanh cac ion phirc
6.8 . 2 . Su tao phUc va do tan
cua hop chat ion it tan
6.8 . 3. Sutao phuc va sir hoa tan
cac hidroxit luong tinh
Bai tap

241
243

247
248
248
254

256
258
259
263

265
266

Chwong 7

PHAN UNG AXIT - BAZO
7.1. Tinh chat doc dao cua proton
268
7.2. Thuyet axit - bazd Areniuyt
269
7.3. Thuyet axit - bazd cua Bronstet va Lauri
270
7.4. Life axit - bazd Bronstet
275
7.4 . 1 . Tich so ion ciia nude
275
7.4 . 2 . Khai niem ve pH va pK
276
7.4.3 . Xac dinh pH, chat chithj
278

7.4 . 4 . Luc axit
280
7.4 . 5 . Luc bazd
286
6
.
quan
7.4 . Moi
he giura lire ciia axit va lire ciia
bazd lien hop vdi no
289
7.4 . 7 . Nhung yeu to anh hudng
den lire axit va bazo Bronstet
290
7.5. * Tich so ion ciia dung moi proton
295
7.6. Phan biet life axit - bazd Bronstet
trong cac dung moi
296
7.6 . 1 . Trong dung moi nude
296
7.6 . 2 . Trong dung moi khac nude
300
7.6. 3 . Ham axit , pH hieu dung
va pKa quy doi . Sieu axit
304
7.7. Life axit- bazd trong pha khi
312
7.8. Dung dich dem
317

7.8 . 1 . Tinh pH ciia dung dich dem
317
7.8 . 2 . Tac dung ciia dung dich dem
319

7.9. Sir dung moi phan cua muoi
7.9 . 1 . Sir thuy phan cua muoi
7.9 . 2 . Hang so thuy phan va do thuy phan
7.9 . 3 * . Sir dung moi phan cua cac muoi
7.10. Phan ting trung hoa.
Chuan do axit - bazd
7.10.1. Phan irng trung hoa
7.10 . 2. Chuan do axit - bazd
7.11.* Thuyet cac he dung moi
7.12. Thuyet axit - bazd Liuyt
7.12.1 . Axit , baza va phan irng axit - bazd
theo Liuyt
7.12. 2 . * Mot so loai axit Liuyt thudng gap
7.13 . * Phan irng axit va bazd di the
Bai tap

.

'

321
321
325
332

332
332
337
345
349

349
352
359
365

Chwong 8

PHANUNGOXIHOA - KHU
367
8.1. Phan irng oxi hoa - khur
8.1. 1. So oxi hoa va phan irng oxi hoa - khir 367
8.1 . 2 . Phan irng oxi hoa - khir theo
371
cd che chuyen electron
8.1 . 3. Phan irng oxi hoa - khir theo cd che
chuyen nguyen tir
372
8.1.4 . Can bang phudng trinh
phan irng oxi hoa - khir
377
8.2. The dien cut
381
va
1

.
381
8.2. Dien cue the dien cue
384
8.2. 2. Pin Ganvani
8.2 . 3 . Nang luong Gip
va sire dien dong cua pin
387
8.2 . 4. Phudng phap xac dinh the dien cue .
389
The dien cue chuan
8.3. Cfng dung the dien cifc chuan
394
8.3.1 . Luc tudng doi cua cac chat oxi hoa
va chat khir
394
8.3. 2. Dua vao the dien cue chuan
de viet phan irng oxi hoa - khir tu dien bien 396
8.3 . 3. Tinh sUc dien dong cua pin Ganvani va
bien thien nang luong Gip d dieu kien chuan 399
8.3 . 4. Dudoan chieu dien bien
ciia phan irng oxi hoa - khir
401

7


402
8.4. Day dien the cua cac kim loai
8.4 . 1. Cac yeu to anh hudng tdi the dien cue cua

402
cac kim loai
day
cua
dien
hoa
the
va
Day
dong
hoat
hoc
8.4 .2.

cac kim loai
8.4.3. Sir dung day dien the
8.4 . 4 . Hoat dong hoa hoc cua phi kim
8.5. Anh hirdng cua nong do den
the dien cifc va sure dien dong cua pin
8.5.1. Phuong trinh Necstc
8.5. 2 . Hieu irng cua sir thay doi nong do
8.5 .3. Hieu irng cua sir tao thanh hop chat

405
407
411
412
412
413
it tan

415
416
420

8.5 . 4. Hieu ling cua sir tao phOc
8.5.5. Hieu ung cua moi trudng
8.6. Sire dien dong va chieu cua
421
phan irng oxi hoa - khir
8.6.1. Sire dien dong chuan cua pin va
hbng sd can bang cua phan irng oxi hoa - khir 421
8.6.2 . Sue dien dong cua pin va chieu cua phan
423
irng oxi hoa - khir
426
8.6.3.* Yeu to dong hoc
8.7 . * Sir ben oxi hoa - khirtrong nirdc
428
8.7.1. Xay dung mien ben nhiet dong cua nude
428
431
8.7 . 2 . Sir dung midn ben ciia nude
8.7 .3 . Anh hudng cua qua the
8.8 . * CacgiandodtJkienthe
8.8 . 1. Gian do Latimer

432
432
433

8.8.2. Ling dung cua gian do Latimer
8.8.4. Sir dung gian do Frost
8.8.5 . Gian dd Frost co dieukien
8.9.* Khuynh hirdng ben cua cac
trang thai oxi hoa ciia kim loai
8.9.1. Cac kim loai hp d
8.9.2. Cac kim loai nhom IB, IIB va
cac kim loai hp p
8.9 .3 . Cac kim loai hp lantan
8.9 . 4 . Cac kim loai hp actini
Baitap

435
442
445

8

446
446

447
448
449
451

Chuong 9

MOT SO VAN BE LfNG DUNG

CUA PHAN LfNG OXI HOA - KHU
9.1. Pin trong cuoc song
9.1.1. Pin so cap (pin khong nap dien lai)
9.1. 2 . Pin cap hai
(pin tai nap, con goi la acquy)
9.1.3 . Pin nhien lieu
9.1.4.* Nhung phacthao mdi
9.1. 5. Pin nong do
9.2. Dien phan
9.2.1. Cau tao va hoat dong
ciia binh dien phan
9.2. 2. The phong dien. Qua the
9.2.3 . Tien doan san pham dien phan
9.2.4. Cac dinh luat ve su dien phan

1

9.2.5 . Lfng dung cua sir dien phan
9.3.’ Tach cac dern chat tir hop chat
9.3 . 1. Nhiet dong hoc ciia qua trinh khir
oxit kim loai
9.3 .2. Khir quang oxit bang chat khir
9.3 .3. Su khir quang oxit
bang phuong phap dien phan
9.3.4. Tach cac nguyen to bang
phuong phap oxi hoa
9.4 . Sir an mon kim loai va hcfp kim
9.4 .1. Khai niem vd su an mon kim loai
9.4.2.* Gian do Pourbaix
9.4.3 . * Nude thien nhien

9.4.4 . * Su an mon sat
9.4 .5 . Chong an mon sat
Bai tap
Tai lieu tham khao

453
453
455
458
459
461
462

464
467
470
476
477
478
478
483

487
489
492
492
493
496
498
499

501
503


Chang 1

^

MUITEXMJ'nnfxa r era mnfirimxG utfc nyc
Nhiet dong lire hoc la khoa hoc dupe hinh thanh vao gitia the ki 19. Ngay nay , nhiet
dong lire hoc bao gom : nhiet dong lire hoc vat If , nhiet ddng lire hoc k!thuat va nhiet dong
lire hoc hoa hoc.
Nhiet dong lire hoc hoa hoc la khoa hoc ting dung nhflng nguyen If cua nhiet dong lire hoc
vat If vao viec nghien ctiu cac hien tupng hoa hoc. Day la noi dung cua cac chuong I, II, IH va IV.

1.1. M0T SO KHAINIEM VA DINH NGIflA CO BAN TRONG NHIET DONG LUC HOC
1.1 . 1 .HE NHIET DONG

He nhiet dong , dupe goi tat la he, la ph £n cua Vu tru g6m mot so rat Ion tidu phan cau
tao ( nguyen tti, phan tti hay ion )"*dang dupe nghien ctiu va dupe phan each vdi phan con lai
cua Vu tru - nidi trucrng ngodi - bang mot ranh gitii thuc hay ao.
He mo la he co the trao doi vtii moi trucrng ngoai ca chat Mn nang lupng.
Thf du : Khi dun soi mot sieu nude thi nhiet dupe truyen tti ben ngoai vao he, con he
thi mat chat ra ben ngoai dudi dang hoi nude.
He kin la he chi trao doi nang lupng vdi moi trucrng ngoai.
Thi du : Khi cho xtit tac dung vdi axit sunfuric trong mot binh kin :
> Na2S04 + 2H20
he khong mat chat , nhung he da cung cap nang lupng cho moi truting ngoai vi phan ting
toa nhiet .
He co lap la he khong trao doi ca chat lan nang lupng vdi moi trucrng ngoai.

2NaOH + H2S04

1
Thf du : Mot binh Dewar chtia cac cha't phan ting dupe day kfn va bao phu bang mot ldp
each nhiet that day de cho chat va nang lupng khong dupe trao doi vdi moi trucrng ngoai .
Neu trong he khong co mat phan each giua phan nay va phan khac, ma qua do tfnh
chat vT mo cua he thay doi dot bien thi he dupe goi la dong the . Trong truting hpp ngupc lai,

he la di the.

Thf du : Mot coc nude la mot he dong the’, mot coc nude co chtia them vai
da la mot he di the.

l

mau nude

Mot loai binh each nhiet.

9


Toan bo phan dong the cua mot he, ma b do thanh phan hoa hoc va tinh chat vat If tai
moi diem deu dong nhat dupe goi la mot pha .
He di the trong thi du b tren la he hai pha.
1.1. 2. TRANG THAI CUA

MOT HE. THONG SO TRANG THAI

Trang thai cua mot he nhiet dong dupe xac dinh bbi mot tap hop cac tri so cua cac dai

lupng vT mo co the do duoc nhu the tfch, nhiet do, ap suat , khoi lupng . . . Cac dai lupng nay
dupe goi la cac thong so trang thai hay car thong so nhiet dong .
Ngubi ta chia cac thong so trang thai lam hai loai :

Cac thong so nfdng do nhu : nhiet do, ap suat, nong do, chiet suat , ti khoi , do nhbt . . .
Chung khong phu thuoc vao luong chat cua he .
Cac thong so khnech do ( variable extensive ) nhu the tlch , khoi lupng . . . Chung ti le vbi
lupng chat cua he .
Trang thai cua he ma b do cac thong so cubng do tai moi chb cua he dong dbu va co
gia tri xac dinh dupe goi la trang thai can bang .
1.1 .3. BIEN DO! CUA MOT HE

Mot he nhiet dong bien doi khi trang thai cua he thay doi. Di £ u nay tuong ung vbi su
bien thien cua mot hay nhieu thong so trang thai . Bien dbi dupe xac djnh neu trang thai dau
va trang thai cuoi dupe biet ro. Dubng bien dbi chi dupe xac dinh khi trang thai dau , trang
thai cuoi va tat ca cac trang thai trung gian ma he da trai qua ddu dupe biet.
Mot bien dbi dupe goi la /; bkhi trang thai dau va trang thai cubi cua he khac nhau .
Mot bien dbi dupe goi la kin khi trang thai dau va trang thai cubi cua he giong nhau .
Bien dbi kin con dupe goi la chit trinh.
Mot bien dbi dupe goi la thnan nghich neu nhung trang thai trung gian ma he trai qua
dupe xem nhu trang thai can bang . Co the’ xac dinh don gian tinh thuan nghich cua mot
bien dbi bang each xet xem bien dbi ngupc lai co the xay ra dupe hay khong, khi chi thay
dbi chut ft tri so cua mot hay nhieu thong so trang thai .
Bien dbi dupe goi la doan nhiet neu no dibn ra trong dibu kien he khong trao dbi nhiet
vbi moi trubng ngoai .
Khi bien doi dupe thuc hien trong dibu kien ap suat khong dbi, no dupe goi la bien doi
dang dp , con trong dibu kien the tfch khong dbi - bien doi dang tich .
1.1 .4. HAM TRANG THAI

oucwg bibn doi a

1.1.4.1. Dinh nghla
Mot ham F cua cac thong so trang thai x , y
se la mot ham trang thai neu gia tri cua no, dbi
vbi mot trang thai cua he, chi phu thuoc vao cac
10

F2 (X2

&uan g bien a6i t>

h)


thong so trang thai va hoan toan khong phu thuoc vao cac bien doi ma he da trai qua trirdc do.

F2 co cung trj so doi voi cac qua trinh a hay b.

1.1.4.2. Nhung tinh chat toan hoc cua mot ham trang thai

Trong mot bien ddi vo cung nho, do bien thien dF cua mot ham trang thai F( x ,y ) cua
cac thong so doc lap x va y la mot vi phan toan phan :
•

J


dF =

.

(fjydX

dF

]

( 1.1 )

yJx dy

5

laadao
dao ham rieng phan cua F doi voi x ( y khong doi ).

Nhung ti'nh chat dac trung cua mot vi phan toan phan dF la :

Srr

^ ^
th & iH

yf dF( x y ^ = F

2 ( x 2 > Y 2 )l

’

~

F[tfang thai 1 (x y

^ J

^

( 1.2)

Tri so cua tich phan chi phu thuoc trang thai dau va trang thai cuoi.

Khi he thuc hien mot chu trinh, thi :

frrfIo!hiil d F( x’

F FIranS thai 1 ] - Fftrang thai 1 ] = 0

( 1.3)

Tinh chat cuoi cung :

v J

dy dx

^

dx Sy

J

l .1.4.3. Mot so thi du ve ham trang thai

J ) The' nang la mot ham trang thai
Xet he gom mot vat co khoi luqng
m . Trang thai 1 dupe xac dinh bdi tri so
h| cua thong so trang thai h ( hinh 1.1 ).
The nang cua he E [

=

Khoi m

9

T"

,

mgh + k , k la

mot hang so, g la gia toe trong luc.

6

dp cao h 2, the nang cua h £ la mgh 2 + k.
Hien nhien hieu cac the nang E2 - Ej =

= mg ( h2 -. hj ) khong phu thuoc vao

each chuyfin he ( 2a va 2b) t £r do cao h|

Trang thai
dau

Trang thai
cuoi 2 a

Trang thai
cuoi 2b

Hinh 1.1

xuong do cao ho.
11


2 ) Tich PV cua mot khoi khi li tuong la mot ham trang thai . 6 trang thai (Mu khd'i khi
dupe dac trung bdi cac tri so Pj , Vj . Sau mot loat bid'n d6i , khoi khf d vao trang thai can

bang cuoi ciing dupe dac trung bdi cac tri so P2 va V 2 . Du cho dudng bien doi co nhu the

nao thi hieu P2V2 - PjVj vSn chi la mdt.
1.1 . 5 . CONG VA NHIET
1.1.5.1. Cong la mot trong cac dang truydn nang luong tur he lam cdng den he nhan
cdng . Nang luong cua he lam cdng thi giam , con nang luong cua he nhan cdng thi tang . Hai
thi du sau day minh hoa cho dieu nay .
1 . Khi nang mdt vat co khoi luong m len mot dd cao h so vdi mat dat ta da tac dung
vao vat mot cdng W :
W = mgh

g- gia toe trong luc

Ket qua la nang luong (the nang ) cua he tang mdt luong la :
AE = mgh
'

2 . Neu ta lam cho mot vat tu do co khdi luong m chuyen ddng theo phuong x vdi mdt
gia td'c co' dinh a, trong sudt quang dudng x2 - Xj thi cdng tac dung len vat la :
W = ma( x 2-Xj )

Vi x2 - X|=

v2 + v .

— Lt

va v2 - Vj

= at

trong dd, v , , v2 la td'c do cua vat d cac diem x 1 x 2 nen :
?

v- - v .

W = ma(x2-xl ) = m. -2 —

?=
—

—
Edn
£

--Lj-± t = V

.

+ v,

mv,

.

mv

2

-

EM

Nhu vay, khi tac dung cdng W vao he ta da lam tang nang luong (ddng nang ) cua no.

Ket luan : Cdng la mot dai luong dac trung cho mite do trao doi nang luong thong qua
chuyen dong co huefng cua he .

Trong he don vj SI, cdng dupe tinh bang Jun (J ). Theo quy ude hidn hanh, cdng dupe
tinh la duong ne'u no do moi trudng xung quanh tac dung vao hd, trong trudhg hop ngupc
lai cdng co da'u am .

12


Tri so cua c6ng phu thuoc vao tinh chat cua qua trinh bien doi . Chung ta so sanh c6ng
dupe thuc hien trong qua trinh chuyen trang thai cua mot he khi theo hai con dudng a,b
khac nhau ( hinh 1.2).
P

P

Pi

Pi

P2

P2

-

W = P2AV

VI

V2

V

(a)

,

V2

V

'

V

( b)

Hinh 1.2. Cong duoc thuc hien phu thuoc vao dudng bien doi

C> trudng hop (a ), trude het ta dot nong he d ap suat Pj de lam cho the tich tang tCr V

,

den V 2, sau do la giam ap suat tur Pj den P2 bang each lam lanh he nhung giu nguyen the
tich . C) tracing hap ( b) c6 ng viec dupe tien hanh theo chieu ngupc lai. Cong dupe thuc hien
trong m6 i trucmg hop bang dien tich dudi duemg bieu didn su chuyen hd tu trang thai ddu
sang trang thai cuoi. Gia tri cua chung khac nhau rat nhidu.
Nhu vay, cong khong phai la ham trang thai ma la ham so cua qua trinh hay hum qua trinh.

Baitqpl .l

1. Khi cho axit sunfuric loang tac dung voi natri cacbonat ran thi cong dupe thuc hien
la duong hay am .

2. Neu lupng natri cacbonat la 0,1 mol, lupng axit dupe dung du, didu kien thi nghiem
la 1 bar va 273 K thi cong do bang bao nhieu ?
Ldi gidi

1. Khi H2S04 loang tac dung vdi Na2C03 ran thi khi C02 dupe phong thich vao mPi
trudng ngoai . He da lam cong va cong dupe coi la am .
2. Na2C03 + H2S04(dlI)

> Na2S04 + C02t + H20

Lupng C02 dupe giai phong la 0,1 mol d dieu kien 1 bar va 273 K.
Vay cong dupe thuc hien la :
W = - 0,1RT = - 0,1.8,314.273 = - 227 J

13


1.1.5.2. Nhiet

Giong nhir cong , nhiet cung khong phai la mot dang nang lupng. Neu cung cap cho he
mot nhiet lirpng ( bAng each lam nong he ) nhung giCr cho the’ tich cua he khong doi thi nhiet
do ciia he se tang len Chuy6n dong h6n loan cua cac phan tir se manh len . Khi do, theo
thuyet dong hoc phan tu nang lupng (d day la noi nang) cua he tang. Nhiet ma he nhan
dupe cang ldn thi nang lupng cua he tang cang nhi £ u .
,

Vay , giong nhu cong, nhiet cung la mot dai lupng dac trung cho muc do trao doi nang
lupng . Su khac nhau la d cho trong trudng hop nay su trao doi nang lupng dupe thuc hien
thong qua chuyen dong hdn loan cua cac phan tu.

'

Nhiet cung khong phai la ham trang thai , J .P.Joule la ngudi dau tien da cluing minh
dupe rang : BAng each dung nhiet hoac cong co the’ dAn den cung mot su thay doi trang
thai . Di 6 u nay co nghla la lupng nhiet dupe dung lam thay doi trang thai cua mot he phu
thupc vao tfnh chat ciia bien doi . Neu bien doi xay ra theo con dudng ma d do chi co cong
dupe dung thi nhiet dupe dung bAng khong , con neu bien doi xay ra theo con dudng ma d
do chi co nhiet dupe dung , thi dl nhien nhiet dupe dung khac khong .
Nhu vay , giong nhu cong, nhiet dupe dung phu thupc vao con dudng bien doi giua cac
trang thai . Nhiet khong phai la ham trang thai, no la ham qua trinh .

Trong he don vi SI, nhiet dupe do bAng Jun . Vi If do lich sir ngudi ta vAn con dung don
vi calo. Mot calo bAng 4, 184 Jun .
Theo quy ude , nhiet co gia tri duong khi he thu nhiet va co gia tri Am khi he toa nhiet.

1.2. NGUYEN LI THU NHAT CUA NHIET

DONG LUC HOC

Nguyen li thu nhat ciia Nhiet dong luc hoc ( goi tAt la nguyen It I ) hay con dupe goi la
nguyen H bao toan nAng lupng khAng dinh tmh bat diet ciia nang lupng . Nguyen li dupe rut
ra tir viec tong ket kinh nghiein ciia loai ngudi va khong chung minh dupe bAng con dudng
li thuyet . Tuy nhien , no dupe thira nhan khong phai chi vi ban than no khong mau thuAn vdi
thuc nghiem , mil con vi moi lie qua dupe rut ra tir do dAu phu hop vdi thuc nghiem .
1.2. 1 . PHAT BIEU NGUYEN LI I

Nguyen li I dupe phat bi6 u dudi nhi6 u dang khac nhau . Cac dang nay deu tuong duong
va ta co the tir dang nay suy ra nhung dang khac mot each hoan toan chat che . Sau day la
mot dang ciia nguyen li.

Nha Vat If hoc Anil .

14


Khi mot he kin tlu/c hien mot chit tn'nh , tong dui so nin cue cong W va nhiet Q mu he
truo doi vo'i moi tnfdng ngoui hung khong .

I(Qi + w, ) = o

( 1.5)

Hien nhien la tong noi b tren khong the khac khong. Vi neu tong nay khac khong thi
cfing co nghla la ta co the thu dupe nang lupng th hir vo hoac bien nang lirong thanh hu vo,
va dieu nay hoan toan mau thuSn voi thuc te.

Plurcmg trinu ( 1.5) cho thay riing, khi he thirc hien mot chu trinh, neu nhan cong no se
nhubng nhiet, con neu nhan nhiet no se sinh cong. Neu goi mot dong co hoat dong tufin
hoan sinh cong ma khong can nhan nhiet la dong co vlnh cuu loai I thi co the khang dinh
" khong the co dong co vTnh ciht loai / ". Day cung la mot each phat bieu cua nguyen IfI.
1.2. 2. MAM TRANG THAI NOl NANG U
Dura trdn nguyen If I, chung ta chung minh rang co ton tai mot hum noi nang .

Gia sir mot he km thuc hien mot bien doi AB theo hai con duong 1, 2 roi sau do lai
quay vd trang thai ban dau theo duong 3 (hinh 1.3 ). Nang luong ma he trao doi voi moi
trubng ngoai trong moi trubng hpp la :

,

,

W2

+ Q2

W + Q

I

Ap dung lan luot nguyen If I vao
cac chu trinh 1 -3 va 2-3 ta dupe :

,

w + Q, + W 3 + Q3 = 0

Thong so trang thai 1

Hinh 1.3

w2 + Q2 + w3 + Q3 = 0
Suy ra :

,

,

'

W + Q = W 2 + Q2 = . .. = const = ( W + Q)

J

Const - chu viet tdt cua chu constant ( Anh) hay chu constante (Phap) co nghla la hing so.

15


Nhu vay , gia tri cua tong W + Q doi vdi mot bien doi bat kl cua he km khong phu
thuoc vao duPng bien doi ma chi phu thuoc vao diem di va diem den. No bieu thi dp bien
thien cua mpt ham cua cac thPng s6 trang thai cua he. Ham trang thai nay dupe goi la
noi nang U cua he .

UB ~ UA = (W + Q)
hay

AU = W + Q

^

(1.6)

Noi nang U cua mot he bao g6m : dpng nang cua chuyen dong tjnh tien va quay cua
cac phan tu, nang lupng dao dong npi phan td cua cac nguyen tir va cac nhom nguyen tu,
nang ltrpng cua cac electron, nang ltrpng hat nhan nguyPn tir .. . Tom lai, do la tat ca cac
dang nang ltrpng , trir the nang do vi tri cua he trong khong gian quy dinh va dpng nang cua
chuyen dong toan hp.

Khong the xac dinh dupe tri so tuyet doi cua noi nang mot he khi no a vao mot trang
thai nao do, ma chi xac dinh dupe dp biPn thien cua no khi he chuyen tir trang thai nay sang

trang thai khac.

Cac he thtfc (1.5 ) va (1.6) la cac bieu thde toan hoc cua nguyen If I.
Trong ba dai lupng a he thde (1.6) chi co bien thien noi nang AU la dupe xac dinh boi
trang thai dau va trang thai cuPi cua he va khong phu thuoc vao duPng bien doi. Hai dai
lupng con lai -nhiet va cPng- khong co tinh chat ay. MPi dai lupng phu thuoc rieng re vao
each thuc hien biPn doi, mac dii tdng cua chung thi khong .

Neu su bien d6i cua he la vo cimg nho thi bieu thde toan hoc cua nguyen li I co dang :
dU

= 8W + 8Q

(1.7)

C) day, dU la vi phan toan phan cua npi nang cua hp, 8W va 8Q la nhung lupng nhiet va
cong vo ciing nho.
He thde (1.7) la bieu thurc vi phan cua nguyen li I. Trong he thirc nay, 8W la cPng

chong lai cac luc ben ngoai, bao gom cong chPng ap suat ngoai hay cong gian nP - PngdV
va cong chPng cac luc dien, luc tir ... goi chung la cong co ich 8W .

8W = -PngdV + 8W’
Trong Nhiet dong luc hoc, nguPi ta thuong chi xet nhung he khong chiu tac dung cua
dien truong , tir truPng . . ., khi do 8W chi la cong gian no va bieu thde vi phdn cua nguyen li
I co dang :
16


dU

= 6Q - PngdV

( 1.8)

Sau day la mdt s6 trudng hop dac biet can phai chu y .
1 . Bien doi doqn nhiet

Trong bien doi doan nhiet Q = 0. Bieu thdc toan hoc cua nguy6n li I co dang : AU = W

Dac biet vdi chu trinh : AU = W = 0
Mot Mn nua chung ta lai thay : mdt he chay theo chu trinh khdng trao ddi nhiet vdi ben
ngoai khong the sinh cdng.

2 . Bien doi dang tich
Trong bien doi dang tich AV= 0. Do do, nd'u 5W chi la cdng gian nd thi 8W = -PngdV = 0
va ta co :
dU = 8Q

AU =

J
=

(1-9)

8Q = QV

V const

Nhu vay, Qv bang do bien thien cua mot ham trang thai ( AU ) va khong phu thuoc vao
diicmg bien doi . Can chu y rang, Qv khdng phai la mdt ham trang thai nhung co the giu vai
tro cua ham trang thai trong dieu kien nay.

3. Gian nor vao chan khong
Qua trinh gian nd cua khl vao chan khdng didn ra ra't nhanh nen co th coi la doan
nhiet, Q = 0. Ap suat cua chan khdng bang khdng ndn he khdng sinh cdng, W = 0. Do do :

^

AU = 0
Khi gian nd vao chan khdng , noi nang cua he khong thay dSi.

4 . He thuc hien chu trinh
Khi he thuc hien chu trinh AU = Uj-U! = 0. Do do W + Q = 0. Nhu vay , khi he nhan
nhiet , thi no se sinh cdng va tro thanh dong co nhiet.
5 . He co lap

Khi mot he nhiet ddng la cd lap, no khdng th£ trao ddi nang luong vdi mdi trudng
ngoai W = 0 va Q = 0. Vay AU = 0. Noi nang cua mot he cd lap la khdng doi.
2-CSLT...

17


6 . Noi nang cua mot khi H tuang
NguPi ta da chung minh dupe ring noi nang cua khi li tirdng chi phu thupc vao nhiet dp :

Uk„= U (T)
Do do, trong mot bien doi dang nhipt cua khi li tuang, khong kem theo phan ting hoa

hoc, bien ddi noi nang AU blng khdng.

1.2.3. HAM TRANG THAI ENTANPI H
Xet mpt he khong co the thuc hipn cong co ich.
dU = 5Q - PngdV

Trong qua trinh dang ap, khi Png = Phg = P, ta co :
dU = 5 Qp - PdV

.

Vi dP = 0, nen PdV = PdV + VdP = d(PV)

va

5QP = dU + d(PV) = d( U + PV)

Dailuong

H = U + PV

(1.10)

dupe goi la entanpi cua hp. H la mpt ham trang thai vi U va PV deu la ham trang thai.

DPi vPi khi li tuong thi PV = nRT, do do :
H = U + nRT = H(T)

(1.11)

Nhu vay:

5QP = dH
va

QP = AH

(1.12)

GiPng nhu Qv , Qp khong phai la mpt ham trang thai, nhung co the giti vai tro ham
trang thai trong difeu kien nay .
1.2.4. NHIET DUNG
Nhiet dung trung binh
nghTa bang hp thtic sau :

18

Ctb cua mpt he trong khoang nhiet dp tu T[ dPn T2 dupe dinh


T2 - TJ

AT

(1.13)

Q la nhiat lupng phai cungdp cho he da’ nang nhiat d6 cua no tur Tj da'n T2.

, -» T2, nghia la AT->dT va Q-»5Q, ta co nhiet dung thuc C cua ha tai nhiet do Tj

Khi T

•

C

_ 6Q

(1.14)

dT

Neu qua trinh nau nong he la ding tich va he khPng lam cdng co ich thi ta co nhiet
dung dang tich Cv

.

6Qv

Cv =

(l)

dT

(1.15)

C5 day, ta dung dao ham rieng va ki hieu d vi U la ham khdng phai chi cua m6t bie'n s<5.
Na'u xet mot mol chat nguyen chat thi nhiat dung trong diau kian the tich khdng doi la
nhiat dung mol

Cv

au

Cy

5T v
'

Khi ha duqc nlu nong trong diau kien ap suit khdng d6i vi chi co cPng gian nor la
dang cong duy nhat dupe thuc hian, thi ta co nhiet dung dang dp Cp.

CP =

—

5QP
dT

o,

(1.16)

D6'i vori mot mol chit nguyan chit :

CP

dT

( 1.17)

'p

Nhiet dung dang ap Cp lu6n lu6n lorn horn nhiat dung dang tich Cv, vi su nlu nong
trong diau kian ap suit khong d6i co kern theo c6ng gian nor. D6'i vori khi li tuong co thi tim
phuorng trinh lien ha giua

Cp va Cy nhu sau :

Trong truomg hop khi li tuomg : H = H (T) va U = U(T)
19


Cp

_ dH

v dT

dU _ d(H - U ) _ d( PV )
dT
dT
dT

=

d(RT)
dT

Cp - CV = R

Vay :

(1.18)

Trong nhiet d6ng lire hoc ngtfcri ta cung dung ti sd :
(1.19)

Bui tap 1.2. Cho 100 g niter or nhiet d6 0 °C va ap suat 1 atm . Tinh nhiet Q va c6ng W,
bie'n thien noi nang AU va bie'n thien entanpi AH trong cac bie'n d6i sau day duorc tie'n hanh
thuan nghich nhiet d6ng.

1. Nung nong dang tich tori ap sua't bang 1,5 atm ;

2. Gian dang ap tori the tich gap d6i the tich ban dau ;
3. Gian dang nhiet tori the tich 200 1 ;

4. Gian doan nhiet cho tori th£ tich 200 1.
Cha'p nhan rang niter la khi li tuomg va nhiet dung dang ap khong doi trong qua trinh thi
nghiem va bang 29,1 J.K-1 .mol-1
Lffi

gidi :

1. Vi V =const nen W = 0
AU = Qv

= nCy (T2 - Tj) = n( Cp - R )(T2 - Tj) = n( Cp - RX

^

= —28 (29,1 - 8, 314)(—1 .213,15 - 213,\5 ) =10138 ,74 J
AH

= nCp (T2- T1)
:

—28 .29,1.(—1 .273,15 - 273,15)=14194 ,05 J
,

2. QP = AH = n Cp (T2- T ) = n Cp (

20

Vl

T J-T J )

- Tj- Tj)


—100 .29,1.(2.273,15 -273,15) =28388 J

^

W = - PAY = - nR (T2 - T1 ) = - nR (
100

=—

Vl

. 8,314.273,15 = - 8110 ,6 J

- T1-T1)

AU = Q +W = 28388 - 8110 = 20.278 J

3. AU = AH = 0
Q+W=0

J

J

|2 -PdV = +|2 nRT

Say ra Q = - W = -

=

—

100

28

200

^^—

.8,314.273,15.2,3031g

22, 4.

^ ^
= nRTln

-

=7433 J

28

W = - 7433 J

4. D6'i vdi qua trinh doan nhi6t Q = 0. Do do W = AU = nCv (T2 -Tj)

_

TVY 1 = const; y =

D6 tlnh T2 ta phai dung phucfng trinh Poisson

Tivr ' = T2V2

|

1-

'

>T2 = Tl

^

gT2 = lgT, + (y-l )lg - -

^

V

CP
Y=—
Cy

—

,

AH = nCP (T2-T, ) =

i

—Cv—

r -i

L

2/

2

29,1
=1,4
29,1 - 8, 314

lgT2 = lg273,15 + 0,41g

W = AU = nC (T2 - T ) =

^

Q

—

100

28

—80

->T2

= 189,4 K

.( 29,1- 8,314)(189,4 - 273) = - 6207 ,3 J

nn

—28 .29,1(189, 4 - 273) = - 8688 ,4 J
21


13. AP DUNG NGUYEN LI THl/ NHAT CUA NHI$T D0NG LUC HOC VAO HOA HOC
1.3. 1. HIEU UNG NHIET CUA PHAN UNG HOA HOC

Phan ting hda hoc thircmg c6 kem theo hi6n tircmg thu nhidt hay phat nhidt. Nhi6 t cua
mdt phan ting or nhidt dd T la nhidt luqng Q ma h6 phan ung trao d6i vdi m6i truting ngoai
khi cac chat phan ling duqc lay theo ti 16 hop thtic, tac dung hoan toan vdi nhau tao thanh
cac san phdm cung theo ti 16 hop thtic. Lucrng nhi6t nay phu thudc vao each ti6n hanh cua
phan ung vi no la mdt ham qua tnnh. D6’ cho nhi6t phan dng co gia tri xac dinh, ngucri ta
phai quy dinh thdng nhat cac di6 u ki6n ti6n hanh phan ung. Do la :
1. Phan ting duorc thuc hi6n trong di6 u ki6n th6 tfch hay ap sua't khdng d6i.
?

2. Trong sudt qua trinh phan ting khdng co baft ki m6t edng nao duqc thuc hi6n ngoai
c6ng gian net.
3. Nhi6t d6 cua cac san ph&n bang nhi6t d6 cua cac cha't ban dSu.

Khi cac di6 u ki6n tr6n duqc thoa man, nhi6t phan ting se co gia tri hoan toan xac dinh
va duqc goi la hieu ting nhiet cua phan ting hod hoc.
Khi phan ting di6n ra trong di6u ki6n th tfch khdng d6i, ta co hieu ting nhiet dang tich Qv,

^

con trong di6u ki6n ap sua't khdng d6i ta co hieu ting nhiet dang dp QP .

Nhu da trinh bay a muc 1.2, Qv bang bi6'n thi6n ndi nang cua phan ting, con QP bang
bi6'n thi6n entanpi cua phan ting.

Qv = AU

;

QP

= AH

Nhu vay, chting giu vai tro cua cac ham trang thai. Nghla la, hieu ting nhiet dang tich
hay dang dp cua phan ting hod hoc chi phu thuoc vao ban chat va trang thai cua cac chat
ddu va cac chat cuoi , hoan toan khdng phu thuoc vao dieting bien doi hay each tien hanh
phan ting. Ta't ca cac phep tfnh v6 hi6u ting nhi6t cua phan ting hoa hoc d6u dua tr6n tmh
chat co ban nky.

Trudc khi nguydn If I ra dcri, tinh chat co ban vtia duqc tiinh bay d tr6n da duqc

G.Hess1- phat hi6n bang thuc nghidm vio nam 1841. Phat ki6n niy la "dinh luat Hess" mdt dinh luat quan trong cua nhidt hoa hoc.

Nha hoi hoc Nga.

22


Hieu ling nhiet cua mpt phan ling hoa hoc phu thudc vao lupng, trang thai cua cac chat
phan ling va cac diPu kien diPn bien cua phan ling. DP thuPn tien va tranh dupe cac sai sot
khi sir dung cac hieu ling nhiet cua cac phan ling khac nhau, ngudi ta thudng tinh hieu ling
nhiet doi vPi mot mol san phPm cua phan ling va cha'p nhan viec quy chung ve cac dieu

kien tieu chuPn xac dinh dudi day :
1. Phan ling dupe thuc hien giua cac chat rieng biet ( nguyen chat) b vao cac trang thai
tieu chudn xac dinh . Cac trang thai tieu chudn cua cac chat ran va long la cac trang thai ben
cua chung a dieu kien thuemg khi ap sua't bang 101,325 kPa hay 1 atm. Thf du : i6t- iot ran,
brom - brom long, cacbon - than chi, luu huynh - luu huynh true thoi, nude - nude long.
Trang thai tieu chuan cua khi la trang thai cua khi nguyen chat b 101,325 kPa hay latm.
Dd'i vdi chat tan trong dung dich thi ndng do cua no bang 1mol/1.

2. Trang thai tieu chudn co the ling vdi mdt nhiet dp bat ki, nhung thudng ling vdi
298K (chinh xac la 298.15K) hay 25 °C.
Hieu ling nhiet ling vdi cac dieu kipn tieu chudn tren dupe goi la hipu ung nhiet tieu
chu <£n va dupe ki hieu bang AH°98 , AU°98 .

Trong thuc te, cac phan ling hoa hoc thudng dien ra d dieu kipn dang ap, do do hPu nhu
ngudi ta chi dung hieu ling nhiet dang ap va goi la bien thien entanpi cua phan ting , hay
dcfn gian hon - entanpi cua phan ting .
Tuy nhien, khi biet entanpi cua phan ling, chung ta co the tinh dupe de dang hieu ling
nhiet dang tich cua phan ling d cung diPu kipn vP nhipt dd.
Qua vay, vdi phan ling viPt d dang :

^1 + 2^ 2

VJAJ + ^ 2^2

> V1

V

L

Ta co :

AHP =AUP
AV =

,

+ PAV

( ; VVI + ;V ) - ( , VAI +
V

V

^

V

V

2

VA 2 )

VA [ , VA ' la thP tich mol cua cac chPt A;, A{ .
Nhu the, khi phan ling diPn ra giua cac ch &'t

ran hoac chat long, thi vi AUP » AUV va
'

AY « 0 nen :
23


AHp = AUV

(1.20)

D6'i v6i nhung phan ting co chat khf tham gia thi 6 ap suri't tha'p ( latm chang han )
nhung khf nay co th£ dirge coi la khf If tubng. Khi do, AUP = AUV (n6i nang cua khf If
tubng chi phu thubc vao nhiet d6) va PAV = AnRT; An - bie'n thien s6 mol khf trong phan
utig. Vi vay :

AHP = AUV + AnRT

(1.21)

Khi An = 0 thi hieu ting nhiet dang ap bang hieu ring nhiet dang tfch ; Khi An * 0
chung khac nhau m6t gia tri la AnRT.

De do hieu ring nhiet cua phan ring hoa hoc, ngubi ta dung nhifit lugng k6'.
Dang ph6 bi£n nha't la dang co phan ring xay ra trong m6t budng phan ring (bom nhidt
lugng ke). D6 tang nhiet d6 dugc do bang m6t nhi6t k6' nhay. Tren hinh (1.4) co tiinh bay so
d6 cua m6t nhifit lugng ke don gian.
Tfch s6' giua bid'n thien nhiet d6 vdi
nhiet dung chung cua nude va nhiet
lugng ke' bang lugng nhiet toa ra.
Phuong phap xac dinh true tie'p
hieu ring nhiet thubng phire tap va
cung chi dung dugc trong trucmg

hgp chi co m6t phan ring xay ra
nhanh va hoan toan. Vi vay, de’ xac
dinh dugc hieu ring nhiet cua nhi£ u
phan img khac nhau, ngoai viec do
true tie'p, ngucri ta con phai dung ca
phuong phap tfnh dua vko cac du:
kien hoa hoc da bie't.

4

1

co
3

Hinh 1.4. So d6 m6t nhiet luqng ke don gi in
( 1 ) Bom nhiet luong ke,
( 2) Nhiet ke , ( 3) May khuay , (4 ) Nu6c

^

Phuong trinh cua phan ring hoa
hgc, ma d do co ghi hieu ring nhiet
cua phan ring, trang thai cua cac cha't (trri nhiing trucmg hgp qua ro) va dieu kien thuc hien
phan ring, dugc ggi la phuong trinh nhiet hoa hgc.

1.3.2. PHUONG PHAP TINH HIEU UNG NHIET
Co scr cua phuong phap tfnh hieu ring nhiet la dinh luSt Hess. Chring ta xet m6t thf du :
Tim hieu ring nhiet cua phan ring

Qhan chi +
24

2

°

2(k)

> C0(k)

(1 )