K600T
ThS.NGUYEN
DINH
DO
GIAI QUYET
NHA
XUAT
BAN DAI HOC
QUOC
GIA HA NOI
THS.NGUYIN
DilMH DO
GIAI
QUYET
NHANH
GON
DE
THI DAI HOC
mon
THI/
ViEN TJNHBIMH TMUAN
Ha Npi
NHA XUAT BAN DAI HOC QUOC GIA HA NQI
Cac em hoc sinh than men
De lam tot bai thi Dai hoc la mong muon cua tat ca cac em trong cac
mua thi. Doi v(5i mon Hoa, day lai la van de bijfc thiet Idn, vi le noi dung de
thi
Hoa
trai
dai ca ba khoi 10; 11; 12 khien
klioi

di, hoc Hoa
khong can phai hoc thuoc long, khong can phai nhcr nhieu nhiJng dieu ma
chi
can qua suy luan c6 the de dang nhan ra chung
(chang
han trong mot
nhom A khi di tCf tren xuong
difdi
thi ban
kinh
nguyen
tii"
cac nguyen to bat
buoc
phai tang dan, do'n gian vi so Idp electron cua nguyen tuf cac nguyen to
nay tang dan).
Nguyen
tSc hoc Hoa la the, tuy vay neu khong c6 ky thuat lam bai thi
trac
nghiem khach quan thi diem so' se khong
nhii
y so v(5i thiic
life.
Do la
thifc
te ma bat cuf hoc sinh nao cung c6 the nhan ra, va day chinh la ly do
ra ddi ciia tap
sach
nay.
Chuc

Vay the nao la phqang phap loai trif? De de hinh dung, h-ay xem mot vi du
sau khong lien quan den Hoa hoc:
Trong
so cac nhiem ky long thong My tie xUa den nay, vi tong thong duy
nhdt doc than den cud'i dai Id:
A.
Bill
Clinton B. Jone F. Kennedy
C. James Buchanan D. Abraham Lincoln
Dap an dung cho cau hoi tren la C
(James
Buchanan).
Nhiftig
ro rang, cau
tra
Idi nay khong phai xuat phat iii sii hieu biet ve than the
James
Buchanan,
vi
vi tong thong
thijf
15 ciia Hop chung
quoc
Hoa ky nay la mot ten tuoi kha xa
la
vdri
chung ta.
Cach
lam d day la dung phqang phap loai
trif:

trCf
not Abraham Lincoln do
cupc
hon nhan day bait
hanh ciia vi tong thong nay da
dqcfc
ghi lai qua kha nhieu giai thoai.
Ro rang
James
Buchanan phai la sii
liia
chon
cuo'i cung!
Chung ta tiep tuc xem mot vi du c6 le gan gui hon vi du
tren,
va van la mot
vi
du khong lien quan den Hoa hoc:
Hoa
iCac
Gidp Than hay con c6 ten Hoa uac Patenotre (Pa-ta-not), Id hoa Udc
cuo'i Cling nha Nguyen ky vai thuc dan Phap. Hoa Uac Gidp Than dugc ky vdo
nam ndo ditai day?
A.
194S B. 1789 C. 1752 D. 1884
Khong dijng
cong
thufc doi nam duong lich
sang
nam am

ngoi vua, lay nien hieu la Gia Long, md dau
trieu
dai nha
Nguyin.
Hoan toan
ttfctng
tii
nhif
tren,
loai
trCr
nSm 1752, vi
trieu
dai nha
Nguyin
chi c6 the bat dau tCf sau nam 1789 (Nguyen Anh len ngoi vua, lay
nien
hieu Gia Long nam
1802).
Vay
liia
chon
cuo'i cung phai la D (nam
1884).
Bay
gid,
ta bat tay vao mot vi du thuoc ve
linh
vifc Hoa hoc:
Co 3 ancol sau:

CH3CH2CH2OH
va
CH3CH(CH3)OH.
Tuy vay de dang nhan ra
phai
loai
trCf
A (ancol IC khong the c6
nhiet
do soi cao han ancol 3C); Cung li
do do, phai loai
trCr
C va D, nen nhanh
chong
tim dtfcJc dap an dung la B
(thUc
te nhiet do soi cua 3 ancol
CH3OH;
CH3CH2CH2OH;
CH3CH(CH3)OH
Ian luat
la
64,7°C;
97,2°C
va
82,3°C).
Vf
du sau day la mot dien
hinh
ro net cho

Cu trong Y phai tac dung vdi AgN03 trong X. Ro
rang
phifcfng phap loai
triT
trong
trLfcfng
hgp nay da to ro tfu the trong giai trac nghiem!
Can biet them rang phifcfng phap loai
tnlf
khong phai chi dimg cho cac cau
trac nghiem ly thuyet. Trong mot so' bai toan ma hudng di con mu mcJ, chiia
the dinh
hinh
thi phucfng phap loai
trif
cung giup ta loai bo cac phifong an sai,
ti^
do xac dinh diicfc dap an ciia bai toan. Cac em hay quan sat vi du sau:
Hoa tan hodn todn m gam Al bdng dung dich HNO3 lodng, thu dugc
5,376
lit
(dktc) hSn hgp khi X gom N2, N2O vd dung dich chiia 8m gam mudi. Tl khoi
cua X so vdi H2 bdng 18. Gia tri cua m Id
A.
17,28 B. 19,44 C. 18,90 D. 21,60
(Dai
hpc 2013 - khoi A)
6
r
Rat

27
neiectron
do Ai cho =
0,70.3
= 2,10 mol < 2,16 mol.
19 44
- Loai trie B, vi neu chon m = 19,44 thi UAI =— = 0,72 mol.Khi dd
2.1
n-eiectron doAi cho =
0,72.3
= 2,16 chitng to khdng tgo NH4NO3.
Do dd
rn.,nu6i
= rn + 62(10.0,12 + 8.0,12)
^
8m <=> m - 19,13-^19,44.
Vdy chon D.
Cdch
khdc
Nhif
tren
da noi, ta chi dung phuang phap
loai
triT
khi
hiTdrng
giai
bai toan
con
mcf ho,

todn electron cho 3—=
0,12.10
+
0,12.8
+ 8-^ « m = 21,6.
11 720
Hoac
trong vi du sau thi
phi/ang
phap
loai
trCf
the
hien
ro lAi diem trong
giai
trac
nghiem:
Hidro
hda hodn todn
0,025
mol hdn hgp X gom hai andehit can 1,12 lit H2
(dkc).
Mat khdc, khi cho cung lUgng X tren phdn ling vdi mot lUgng dU dung
dich
AgNOs trong NH3 thi thu dugc 8,64 gam Ag. Cong thiCc can tgo cda hai
andehit trong X Id:
A.
OHC-CH2-CHO vd OHC-
CH2-CH2CHO

lieu
da cho la
khong
day du thi
phifcfng phap loai
tnf to ro la mot sir
liia
chon
toi UU.
That
vay,
ta xet vi du sau:
X la chat hOu ca tdc dung vai Na diC cho so mol H2 bay ra b&ng so mol NaOH
can
diing de trung hba het cUng luang X tren. Cong
thiCc
phan tit cila X Id
A.
C4H8O2. B.
CeHi403
C.
C7H12O2.
D.
CgHioOz
De
dang loai
trtr
ngay B vi
CGHMOS khong phan tfng
di/oc

trung
binh
= so'
nhom
OH
trung
binh
- ^ = 1,66. Vay
chon
D,
tufc
2
ancol tren
la CH3OH va C3H5(OH)3.
BAI
TAP AP DUNG
1. Cho bot Mg va Fe vao
dung dich
gom AgN03 va Cu(N03)2. Sau khi cac
phan
ufng
xay ra
hoan toan,
thu
difcfc dung dich
X gom ba
muoi
va
chat
ran Y gom

nhQng
chat
nhii the; tuang tu Id
loai
trie
ngay
B vi Cu
trong
Y phdi tdc
dung vai FefNOsJs vd
AgNOs
trong
X, vd
cuoi
cung
loai
trit
ngay
C vi Cu
trong
Y
phdi tdc dung vai Fe(N0s)3
trong
X. Vdy
chon
D.
2. Cho hon hcfp gom Fe va Mg vao dung dich AgNOa, khi cac phan
uTng
xay ra
hoan

dap dn A.
Vdy
chon
A.
3.
Thi nghiem nao sau day chufng to trong phan tuf glucozcf c6 5 nhom hidroxyl?
A.
Khijf
hoan toan glucozcf thanh hexan.
B.
Cho glucozcf tac dung vdri Cu(OH)2.
C.
Tien hanh phan ufng tao este
ciia
glucoza vdri anhidrit axetic.
D.
Thifc hien phan ufng trang bac.
Gidi
Loai trie A vi day Id thi
nghiem
de chiing minh phdn td
glucoza
c6 6C
khong
phdn nhdnh.
Loai trii B vi ddy la thi
nghiem
de chiing minh phdn tit
glucoza
c6 cdc

nghich.
Loai trie B, D vi
tang
nhiet
dp thi can bdng se
chuyen
dich
theo
chieu
nghich.
Vdy
chon
C.
9
5. Cho phircfng
trinh
hoa hoc: 2X + 2NaOH >
2CH4
+
K2CO3
+ NagCOg
Chat X la
A.
CH2(COOK)2 B. CH2(COONa)2 C. CH3COOK D. CHgCOONa
Gidi
Loai
trii
A, B vi
khong
bdo

rdng
vai
dang
bdi tap nay, chi can
phdt hicn
mot
loai
ta
trong
niSi
ddy
da cho
khong phdi
Id to
nhdn
tao thi ta
loai
trii
ngay. Vdy di
ddng loai
trii
A,
B, C vd
chon
D. (ta
nilon-6,6;
ta
capron;
ta
vinilon

va ta nilon-6 D. sgi
bong
va ta
visco
(Dai
hoc 2013 - khoi B)
Gidi
Tuang
tu nhu can 6 a
tren,
ta
loai
trii
ngay A, B, C vd
chon
D (ta tdm; ta
nitron;
ta
nilon-6 khong
c6
nguon
goc til
xenluloza).
Vdy chon
D.
8. Cho cac phat
hiiu
sau:
(a) Trong bang
tuan

CrOs la oxit axit; CrsOs Id oxit
liiang
tinh). Vay
chon
B.
9. Cho cac chat : caprolactam (1), isopropylbenzen (2),
acrilonitrin
(3),
glyxin
(4),
vinyl
axetat (5). Cac chat c6 kha nang tham gia phan uTng
trung
hcfp tao
polime la
A.
(1), (2) va (3) B. (1). (2) va (5) C. (1), (3) va (5) D. (3), (4) va (5)
Gidi
Vi
caprolactam
(1) cho
dugc phan
iXng triing hgp,
nhitng
isopropylbenzen
(2)
khong
cho
dugc phan
iCng

bdng
chuyen
dich
nen
loai
trie
ngay
A, B, C. Vgy
chon
D.
11. Cho bon dung dich c6 cung nong do mol sau day:
(1)
H2NCH2COOH,
(2) CH3COOH, (3) CH3CH2NH2 va (4) C2H3COOH.
Day xep theo
thuf
tiT
pH tang dan la:
A.
(3), (1), (2), (4) B. (4), (1), (2), (3)
C. (2), (3), (1), (4) . - D. (4), (2), (1), (3)
Gidi
Khong
it hoc sinh boi roi a cdu hoi ndy do
khong
ndm
dUgc
luc axit cua axit
chita no C2H3COOH Id
mgnh

dung
dich
CH3COOH
phdi
CO
pH < 7 nen
loai
trie
tiep
B. Vgy
chon
D.
12. Cho hSn hcfp X gom Fe203, ZnO va Cu tac dung \6i dung dich HCl (diT) thu
di/cfc dung dich Y va phan khong tan Z. Cho Y tac dung vc;i dung dich NaOH
(loang, du) thu
d'Jgc
ket
ttia:
A.
Fe(0H)3 va Zn(0H)2 B. Fe(0H)2. Cu(0H)2 v^ Zn(0H)2
C. Fe(0H)3 D. Fe(0H)2 Cu(0H)2
11
Gidi
Phdn
khong tan Z Id Cu con du, do do khong the tqo muoi Fe^*, tiic khong
the tqo ket tua Fe(0H)3, vdy
loqi
trie A, C.
Do NaOH du nen ket tua khong the cd hidroxit
liidng

dugc
m' gam hon
hgp ran T. Biet m > m'. Vay ran Z va T Ian
Itfot
la
A. Cu; Mg; Fe va MgO;
FegOg.
B. Cu va MgO;
FeaOg.
C. Cu; Fe va MgO; CuO;
FegOg.
D. Cu; Fe va MgO;
FegOg.
Gidi
Can
luu y rdng Mg c6 tinh
khvC
mqnh han Fe nen Mg se phdn Ung
trUdc
vdi
CuCh
Chi khi Mg phdn iZng het, mdi tdi lugt Fe phdn ilng. Vdy:
Loqi
tril
A, do Mg con thi Fe chila phdn ling nen khong the cd muoi sdt
trong dung dich Y, ddn den T khong the cd Fe203.
Loqi
trii
B,-do Mg
ud

Loqi trie B, vi dung dich Z khi do chi chiia MgCl2, ddn den W chi Id MgO,
khong phai Id hon hap W nhu de yeu cdu.
Loai trie A, vi dung dich Z khi do chiia
MgClo
vd
AICI3,
ddn den W ciing chi
Id
MgO.
Load trilD, vi Y khong the gom Zn; Cu (do Y con Zn thi ciing buoc phai con Fe).
Vdy chgn C.
16.
Day cac nguyen to' diigc sSp xep theo chieu tang dan ban
kinh
nguyen
tijf
khi
di tCf
trai
sang phai la
A. Al; Si; N; O; F B. F; O; N; Si; Al
C. Si; Al; N; O; F D. F; O; N; Al; Si -
Gidi
Loai trCf A, C vi ban
kinh
nguyen ttf F khong the Idn hcfn ban
kinh
nguyen
tuT
O (trong mot chu ki khi di tii

0 4"
"2/
( Q 25 0 2
- Loai trie C vi x = 0,225 thi so O trung binh = ——'- —' ~ ~ ^
Vdy chon D.
Liiu
y
- Cong thiic tinh so O trung binh =
hon hiip
- Vi A chiea 20; B chiea 40 trong phdn tit nen ta phai c6:
2 < so O trung binh < 4
13
18.
X la hon hop gom
andehit
don
chiifc
A va
andehit nhi
chufc
B. Dot
chay
hoan
toan 0,25 mol
X
can
visa
du
x
mol

0,475.2
+
0,325-0,25.2
tni
so U
trung bmn
= =
3,1 (vd
li)
0,25
- Loai
trii
B vi x = 0,35
-n,
i.^ u
0,475.2
+
0,325-0,35.2
till
so
(J trung
bmn = =
2,5(vo
li)
0,25
- Loai
trii
C vi x =
0,525
,

X
gom MO, MCOH)^
va
MCO, (M
la
kim
loai
c6 hoa
tri khong doi) trong
100
gam dung dich
PLSO^
39,2% thu
du'gc
1,12
lit khi (dktc)
va
dung dich
Y chi
chi'ra mot chat tan duy nhat
c6
nong
do
39,41%. Kim loai
M la
A. Mg
B.
Cu D.
Zn
D.

mol
khi - = 0,05.
100.98
Ta
gidi
theo
phuang phdp loai trtt nhii sau:
^
- Loai trie
B vi M
Id Cu
cho ta he:
80a + 98b + 124c
=
24
a H-
b
+
c =
0,4
.
Gidi
ra b < 0
(loai)
c =
0,05
22,4
14
- Loai
trii

+ 96)(a + b + c)100
Af
=
24 (Mg)
=
39,41
24 +
100-44C
20. Cho hon
hcfp
X gom hai
ancol.
Dot
chay
hoan
toan 0,6 mol h6n hep X, thu
dirge 22,4 lit khi CO2
(dkc).
Mat
khac
0,3 mol X tac dung \6\a dii
di/gc
5,6
lit
H2
(dkc).
Hai
ancol
da cho la:
A.

nhom
OH trung binh Id 1).
- Loai trie B (c6 so
nhom
OH trung binh khac so C trung binh).
- Loai
trii:
C (c6 2 < so C trung binh < 3).
Vdy chgn D.
15
m
21.
Thiiy phan
este
mach hd E (chi chufa
chufc
este)
trong moi trufcfng axit thu
diigc hon hap san pham chi gom mot axit
cacboxyUc
va andehit glycoHc
HOCH2CHO.
Cong thufc phan tuf cua E la
A. C7H10O4 B.
C9H14O4
C.
C4H4O4
D.
C4H8O4
Gidi

bac hai.
C. Trong X c6 ba nhom -CH3.
D.
Hidrat hoa but-2-en thu difcfc X
(Dai hoc 2012 -
khoi
A)
Gidi
Trilac
het loai
trii
A vi so mol CO2 nhd han so mol H2O nen X Id ancol no,
khong lam mat mdu nicac brom.
Tiep
tuc loqi
trii
D vi hidrat hoa anken duqc ancol dan chiic no khong cd
khd ndng hoa tan
Cu(0H)2.
Cadi ciing loqi
trii
C vi X chdy tqo 0,4 mol CO2 vd 0,5 mol H2O nen X cd 4C
trong
phdn tit. Ancol da chiic cd 4C trong phdn ti2 khong the cd 3 nhom -CH3.
Vqy chgn B.
23. Cho h6n hgp X gom hai andehit. Dot
chay
hoan toan 0,6 mol h6n hgp X,
thu
dtfgc 44 gam CO2. Mat

35,2 gam CO2. Mat khac cho 0,2 mol X tac dung vdi
NaHCOg
dtf thu difgc 8,96 lit CO2 (dkc). Hai axit cacboxylic da cho la:
A.
CH3COOH;
CH2(COOH)2.
B.
CH3COOH;
C2H5COOH.
C.
(C00H)2;
CH2(COOH)2
D.
CH2(COOH)2;
HOOC-CH=CH-COOH
Gidi
^co 0,4
Be
y rdng hon hap X c6 so nhdm COOH trung binh = ^ = —^ = 2 nen
loai trie A, B.
Mat khdc hSn hap X c6 so C trung binh - = = 2,66 nen loai trie D.
Vdy chon C.
25.
H6n hgp X gom hai axit cacboxylic don chuTc. Dot ch^y hoan toan 0,1 mol X
can 0,24 mol O2 thu
di/gc
CO2 va 0,2 mol H2O.
Cong
thufc hai axit la
A.

AgNOs
trong NH3 thi thu
di/gc
17,28 gam Ag.
Cong
thufc cau tao cua
hai
andehit trong X la: _
A.
0HC-CH2-CH0
va
OHC-CHO
rrjT^T^aTTjJJ^
B. H-CHO va OHC-CHo-CHO '^^ '
17
C.
CH =C-
CHO
va
OHC-CH2-CH2-CHO
D.
CHo-CH-CIiO
va
OHC-CH2-CHO
Gidi
n
Ta
CO
so
lien

luang
dii
dung dich AgNOa trong
NH3 thi thu
duqc
8,64 gam. Ag.
Cong
thufc
cau tao cua
hai andehit trong
X la:
A. OKC-CHo-CHO
va
OIIC-CIIO
B.
H-CHO
va
OHC-CH2-CHO
C. CH2=C(CH3)-CHO
va
OHC-CH2-CHO
B.
CH2=CH-CI-I0
va
OHC-C.II2-CHO
Giai
Ta
CO
so mol Ag
=

dong
dang.
E)ot
chay
hoan Loan.
4,02 gam X, thu
dtfgc
2,34 gam.
H2O. Mat
khac
10,05
gam.
X
phan ufng vCfa
du v6i
dung dich NaOH, thu
di/cfc
12,8
gam
muol.
Cong
thiJc ciia hai axit
la
A.
C3H5COOH va
C4H7COOH
B.
C2H3COOH
va
C3H5COOH.

0,125
' •- •
Mat khdc
so mol 2
axit trong
4,02 gam hSn hap =
^^^^^^^^^
= 0,05
moZ
9
2 2'34
HO
1R
nen
so H
trung binh
cua 2
axil
=
^—
- —~— - 5,2 do do
loai trit
C.
Vqy chon
B.
0,1
18
29. M la h6n hcfp hai chat
hiJu
ccf dcfn chijfc X va Y, thanh phan nguyen to' deu

2y-0,36
[y = 0,02
- Loai
trii
A,
vi neu X chiem 83,33% khoi lugng hdn hap thi ta phdi c6:
-0,08.30
=
= 24 (vd It)
^ 0,02
- Loqi
Irii
C, vi neu X chiem 75% khoi luang hon hap thi ta phdi c6:
0,08.30,10D_^„^3g
=
= 40 (vd It)
" 0,02
- Loqi trie D, vi neu X chiem 90% khoi lugng hon hap thi ta phdi c6:
0,0O0.100_Q^^3
3^
M
= ^ = 1X23 (volt)
^ 0,02
Vdy chgn B.
hiiu
y
- Khong
CO
chat hUu ca ndo chiia C, H, O cd M = 40.
0-««f»°0-0.08.30

trung binh Id 2).
Nhung di so C trung binh Id 2, khi do phdi c6 n^^ =
n^,,^^^,
(trdi gid thiet).
Vay chon D.
31.
H6n hgp M gom ankan A va anken B. Dot
chay
ho^n toan 7,84 Ut (dkc) hcri
M
dtfgc
55 gam CO2 va 27 gam H2O.
Cong
thijfc phan tuf A, B Ian
lifgt
la
A. CH4 va C3H6 B. C2H6 va C4H8
C. C4H10 va C4H8 D. C3H8 va C5H10
Gidi
Ta
CO so C trung binh = =
il^^
= 3 57 figfi
IQQI
trii
A, C.
0,35
2n^ ^ 2.1,5
Mat khdc so H trung binh = ^ = " = 8,57 nen loai trie B.
"HH 0,35

CH2=C-CH2,
CH2=C-C=CH2.
D.
CH2=C=CH2,
CHs^CH-C^CH.
(DQii
hoc 2011 - khoi A)
Gidi
Ggi a la so mol moi chat, ta c6 2a + 3a + 4a = 0,09 <=> a = 0,01.
Chu y rdng chi nhUng hidrocacbon c6 noi ba ddu mach mai tao ke't tua khi
phdn ling vai dung dich AgNOs trong NH3. Vay:
- * Loai frit B-vi mka
tua
(max)
=
240.0,01
+
147.0,01
= 3,87 gam < 4 gam.
- Loai
trii
C vi khong c6 ke't tua tao thdnh.
- Loai
tril
D vi
mkgt
tua
(max)
=
240.0,01

dugc
0,4 mol
CO2 va 0,55 mol H2O.
Cung lifong
X
tren
neu tAc
dung
vdri
Na da
dtfac
2,8 lit
H2(dkc).Xg6m
A.
CH3OH;
C2H4(OH)2
B.
C2H4(OH)2;
C3H5(OH)3.
C. CH3OH;
C3H5(OH)3
D. C2H5OH; C3H6(OH)2.
Gidi
Taco =0,^,-n^^
=
0,55-0,4
=
0,15mo/.
n
CO "

va
hidrocacbon
A. Dot
chay hoan toan
3 lit hoi X
difcfc
6 lit CO2 va 6 lit hoi
nLfdrc
(cac the
tich
do or
cimg dieu kien). Cong thufc
phan
tijf
cua A la:
A.
CH4 B. C2H4 C. C3H8 D. C2H6
Gidi
TrUdc
het
loai trie
B, do dot
chdy
hdn hap
ankin
vd
anken khong
the tao so
mol
CO2 = so mol HoO.

trinh
phan
I'fng
hoa hoc xay ra.
Chinh vi vay toe do giai cac bai toan Hoa hoc khi do se nhanh hern nhieu Ian
so
vdri
viec
giai theo cac
each
truyen thong.
Van de la duTng trifcrc mot bai toan, thi sinh phai biet dung dinh luat nao de
"dut
diem" bai toan cho nhanh, gon, hcfp li, bdi le khong nhat thiet bai toan
nao cung sijT dang cac dinh luat, va nhat la suf dung dinh luat khong phu hcfp se
khien bai toan thay vi difOc giai don gian se trd thanh roi ram hon!
Nhac
lai pham vi SLf dung ciia cac dinh iuat:
1/
Dinh
luat
bdo
toan
khoi
lUting
Dinh
luat nay ap dung tot & cac bai toan hon hop cac
chat
c6
tinh

luat
bdo
toan
dien
tich
Dinh
luat nay ap dung cho cac bai toan lien quan den so mol cac ion trong
mot dung dich; cac bai toan trong do c6 sy thay the ion nay
bang
mot ion
khac
(nhtf
h6n hgp cac oxit kim loai tac dung vcJi dung dich HCl; H2SO;4 loang la sg
thay the ion
bang
ion CI hay ion SO^ ; nhiet phan hon hgp cac muo'i
nitrat
tao cung san pham la cac oxit kim. loai la sg thay the ion NO,
bang
ion
O^ - ) . Tat nhien can
Itfu
y rkng sg thay the nay phai "bao toan dien
tich'',
tijfc
cac ion dtfcfng trong h6n hgp cac cation kim loai phai khong thay doi dien tich
khi
xay ra phan gng hoa hoc.
3/
Dinh

chufc
(c6 2
nguyen tuf O trong phan ttf) giai phong CO2 theo ti le mol 1:1, con cac axit
cacboxyhc
nhi
chufc
(c6 4 nguyen tuf O trong phan til) giai phong CO2 theo ti le
mol 1 : 2.
41 Dinh luat bdo toan electron
Dinh
luat nay ap dung
dufcfc
cho tat ca c^c bai toan c6 lien quan den cac qua
trinh
oxi hoa
khijf
nhif
toan ve hon hop cac kim loai tac dung vdi dung dich chufa
h6n
hop cac muoi; toan ve hon hop cac kim loai tac dung
vtJi
hon hop cac phi
kim;
toan ve h5n hop cac kim loai tac dung v6i HNO3; v6i
H2SO4
dac, nong
Dieu
can nhd khi giai theo bao toan electron la ta chi chu y den mufc oxi hoa
ciia
cac nguyen to d luc ban ddu va luc ket thuc bai toan^khong can quan

day:
Vi
du 1: Hoa tan het 16 gam rdn X gom ZnO; MgO; CuO; AI2O3 can vifa du 300 ml
dung dich H2SO4 IM. Co can dung dich sau phan ufng dtioc m gam h5n hop
mudi
khan. Gia tri m la
• Nhdn xet
• Kliong dung dinh luat bao toan electron do bai toan khong lien quan den
- Miong diing dinh luat bao toan nguyen to do khong c6 dau hieu dac tn/ng
nhii
da noi cf
tren.
• Giai
+
Diing dinh luat bao toan khol liJOng
A. 51,2
B.
48,0
C. 40,0
D.
39,2
phan ufng oxi hoa khuf.
Ta CO mx + m
=
m,
muci
H-
m
H,()
m,„u6i

binh
thu
ducrc
0,448
lit khi NO va dung dich Y. Biet trong ca hai
tri/crng
hop
NO la san phan
khijf
duy nhat, do d dieu kien
tieu
chuan. Dung dich Y hoa
tan
VLfa
het 2,08 gam Cu (khong tao thanh san pham
khijf
cua N*^). Biet cac
phan iJng deu xay ra hoan toan. Gia
tri
cua m la
A.
2,40 B. 4,20 C. 4,06 D. 3,92
(Dai
hoc 2013 - khoi A)
• Nhdn xet
- Khong dung dinh luat bao toan khoi liiang do khong the xac dinh so gam
c^c chat tmdc phan
ijfng
cung
nhtf

+5
NHAN
3e
T+2
0,21mol
N"
0,07mol
0,0325mol
Vay 2a +
0,065
- 0,21 « a =
0,0725
mol.
Do do m =
56.0,0725
= 4,06 gam. Vay
chon
C.
• Luu y
Khi
suf dung dinh luat bao toan electron, ta chi can
liAi
y den mufc oxi hoa
ban dau va mufc oxi hoa luc ket thuc bai toan cua cac chat, khong can quan tam
den mufc oxi hoa cua cac chat d cac giai doan
trung
gian.
Vi
du 3: Hoa tan het hon hgrp gom x mol Al; 2x mol Zn va 3x mol Ag can vifa
du

bai
toan
-
Khong dijng dinh luat
bao
toan khoi iLfcrng
do
khong
c6 dOf
kien
ve so
gam
h6n
hctp khi.
•
Gidi.
+
Dimg dinh luat
bao
toan nguyen
to N
Bao toan
N
cho n^,„^,,^
=
nN/Ai,N<,,),
+^N,ZMNo,^,
+"N/AgNo,
+
^^N/NO

mol
NO2.
De
y
rang
hSn hop kim
loai
da
cho
(3x +
2.2x
+ 3x) =
lOx mol
electron,
con
N"^^
da
nhan
(3a + b)
mol
electron
de
tao
khi,
ta
c6 he:
^
V
a
+

W"^^''^
<=>y
=
lOx
+
22,4
.
Vdy
chon
C.
•
Luu V
+
Nhac
lai
cong
thufc
tinh
so
mol HNO3 can
diJng
khi hoa tan mot hon hop
kim
loai
la : n„^,„ =
4n^„
+
2n^„
+
12n^

buoc
phai giai
theo
bao
toan electron
nhif
sau
:
Gia suf h6n
hop
khi
gom
a
mol NO va
b
mol N2O.
De
y
rang
hon hop kim
loai
khi
do
cung
cho (3x +
2.2x
+ 3x) = lOx
mol
electron,
con N"^^

y
12x + —. Vay chon C.
56
Vi du 4: Hon hcrp X gom Zn(N03)2, Fe(N03)3, Cu(N03)2 va A1(N03)3. Thanh
phan
%
khdi
liicfng cua nitcf trong X la 11,864%. Nung nong 14,16 gam X
den khoi li/cfng khong ddi dtfgc m gam rSn. Gia tri m !a
A. 10,56 gam B. 7,68 gam C. 3,36 gam D. 6,72 gam
• Nhdn xGt
+ Co the dung dinh luat bao tcan dien
tich
do ran thu
dLfgc
la cac oxit, tijfc
CO
°>\i thay the ion NO^ trong muo'i bkng ion .
+ Co the dCing dinh luat bao toan electron do phan uTng nhiet phan cac muo'i
nitrat
la cac phan
I'rng
oxi hoa khijf.
+ Khong dung dinh luat bao toan nguyen to' do khong c6 dau hieu dac triAig.
Tuy vay can bie't dinh luat bao toan nguyen to N cho n^.^^ =
n^^^
de c6 the giai
theo bao toan kho'i
lu'Ong.
9

cho nhan electron sau:
26