Kỹ thuật giải quyết nhanh gọn đề thi đại học môn Hóa học

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

lifgrng
kien thijfc di/cfng
nhii
la ca mot bien
trofi
menh mong, vo tan
That ra, Hoa hoc la mon hoc rat nhe nhang ne'u cae. em biet hoc c6
phqo'ng phap, vi le tat ca phan ufng hoa hoc hay
tinh
chat
hoa hoc cua cac
chat
deu dUofc xac
dinh
thee
cac qui luat. Do do van de la nam dtfOc cac qui
luat
nay thi ta deu c6 the de dang diT doan
tinh
chat
hoa hoc mot
chat,
hay
de dang viet ra san pham phan
ijfng
giffa cac
chat
ma khong can phai hoc
thuoc san pham nhir cac em lam tiio'ng bay lau nay. Noi
khac

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

cac em tim thay niem vui trong hoc tap, va nhat la phai dat diftfc
ket qua my man nhat trong thi cuf.
Tac gia
Nguyin
Dlnh
06
3
O
CHLTdNG
I
KY
THa6T
Gl^l DE THI TR^C
NGHIEM
Mot dieu khong the phu nhan la du ndm rat
chSc
cac kien thijTc trong
sach
giao
khoa, nhieu thi sinh vSn khong the giai quyet tron ven cac cau hoi trong
cac de thi Dai hoc. Mot thqc te la da so cac cau trSc nghiem ly thuyet cung
nhif
bai
tap ma thi sinh xem la rSc roi, di bi mat diem trong cac de thi,
hoac
cac
cau ma thi sinh con mii mcr hay ma ho ve hqdng giai lai c6 the giai quyet rat
tot
bang phtfang phap loai
triT.

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:

Trifdc tien loai
triT
Bill
Clinton vi han chiing ta con nh6 hai vg
chong
tong thong
Bill
Clinton
ti/ng
CO
chuyen ghe tham Viet Nam (nam
2000).
Tiep theo, tong thong
Jone
F.
Kennedy cung nam trong danh
sach
loai
trii,
vi vu am sat ong vao nam 1963
tai
thanh pho' Dallas, tieu bang
Texas
khi dang cung phu nhan tham vieng tieu
bang nay, la mot sii kien chan
dong
the gidi
thcfi
do va hien nay c6 le khong ai
khong biet. Cuo'i cung, loai

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

lich,
ro rang phai
loai
trii
nam 1948, vi
trieu
dai riEa
Nguy§n
ket thuc khi vua Bao Dai tuyen bo'
thoai
vi, trao an kie'm cho dai dien chinh phu Viet nam dan chii
cong
hoa vao
nam 1945. Cung nhanh
chong
loai
trii
nam 1789, vi day la nam vua Quang
Trung
keo quan ra Thang Long tieu diet quan Thanh. Luc nay
trieu
dai nha
5
Nguyin
chtfa diigc t.hie't lap, vi chi khi danh bai
ducfc
nha Tay Scfn, Nguyen
Anh
mcri
xLfng

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:

CH3OH
(I); CH3CH2CH2OH (II);
CHsCmCHsJOH
(III).
TM
tu
tang dan nhiet do soi cda 3 ancol tren
theo
chieu til
trdi
sang phdi la:
A.
(II); (I); (III) B. (I);
(III);
(II) C. (II);
(III);
(I) D.
(Ill);
(I); (II)
Se
CO
rat nhieu hoc sinh lung tung khi doc vi du
tren,
do
sach
giao
khoa
hoan toan khong de cap den nhiet do soi cua 2 ancol dong phan, cu the d day
la
cac ancol

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

viec
sijf
dung phucfng phap loai tni:
Cho bot Fe vdo dung dich gSm AgNOs vd Cu(N03)2. Sau khi cac phan ring
xdy ra hoan toan, thu dugc dung dich X gom hai mudi vd chat rdn Y gom hai
kim
loai. Hai muoi trong X vd hai kim loai trong Y Idn lilat Id:
A.
Cu(N03)2; Fe(N03)2 va Cu; Fe B. Cu(N03)2; Fe(N03)2 va Ag; Cu
C. Fe(N03)2; Fe(N03)3 va Cu; Ag D. Cu(N03)2; AgNOg va Cu; Ag
(Dai
hoc 2013 khoi A)
Khong mat nhieu
thcfi
gian de nhan ra dap an can tim la B. That vay, ta
loai
trii
ngay A, vi Fe trong Y phai tac dung vdi Cu(N03)2 trong X nen sau
phan ufng khong the thu difac nhOfng chat
nhtf
the;
tiicrng
tii la loai
triT
ngay C
vi
Cu trong Y phai tac dung vdi Fe(N03)3 trong X, va cuoi cung loai
trCr
ngay D
vi

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

nhieu hoc sink nhanh chong xdc dinh dugc buac ddu tien d ddy la phdi
tim
so mol tilng khi. Do Id huang di diing! Theo dU kien dd cho, ta cd so mol
N2 = so mol NoO = 0,12 mol.
Tuy
nhien huang di tiep ddi vdi mot so em cd the Id chua ro rang, khi dd ta
dung
philang phdp loai
triC:
Be
y rdng tong so mol electron md N*^ dd nhan de too N2 vd
NoO
=
0,12.10
+
0,12.8
= 2,16 mol, do do:
17 28
- Loai
tril
A, vi neu chon m = 17,28 thi nAi -—'— = 0,64 mol. Khi dd
27
rieiectron
do Ai cho =
0,64.3
= 1,92 mol < 2,16 mol.
18 90 —
• Loai
trii
C, vi neu chon m = 18,90 thi nAi =—'—- 0,70 mol. Khi dd

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,

chifa
xac
dinh.
Neu da n&m dtfcfc
phiicfng
phap
giai
toan ve kim
loai
tac
dung
vori
HNOa,
bai nay di/gc
giai
theo bao toan
electron
nhuf
sau:
Ta
cd so mol N2 = sd mol N2O = 0,12 mol.
Gid
sit mud'i ihu diigc gom ~ mol
AKNOsJs
vd.
x mol
NH4NO3.
Tacd 213 —+ 80x-8m <:> x =
27 720
Bao

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

B.
H-CHO vd
OHC-CH2-CHO
C. CH s C - CHO vd OHCCH2-CHO
D.
CH2=CH-CH0 vd OHC-CHO
Gidi
"H
0,05
Ta CO
so lien ket n truns binh = —^ = — = 2 nen loai trie B, C.
"KK
0,025
hh
'
Mat khdc so mol Ag = 0,08 tiic ux
•'
nAg
= 1 : 3,2 nen phdi loai tril A.
Yqy chon D.
Dieu
dac
biet
la d
nhCfng
cau ly
thuyet
hay bai
toan
ma dcr

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

vcri
NaOH.
Cung loai
tvii ngay A, C vi C4H8O2 va
C7H12O2
giai phong
so mol H2 = — so mol NaOH.
2
Vdy chon D.
Hoac
a vi du sau, do c6 v6 so' h6n hop
ancol thoa
man de bai nen neu sa da
vao gia
thie't
se
khong
the c6 ket qua:
Cho hon hap X gom hai ancol. Dot chdy hodn todn 0,3 mol hSn hap X thu
dugc 22 gam CO2. Mat khdc 0,3 mol X tdc dung vai Na dU diiac 5,6 lit H2 (dkc).
Hai ancol dd cho Id:
A.
CH3OH vd C2H5OH B. CH3OH vd
C3H6(OH)2.
C.
C2H/OH)2
vd C3HdOH)2. D. CH3OH vd C3H5(OH)3.
Ta loai
trif
ngay A, B va C do h6n hop c6 so C

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

hai
kim
loai.
Ba
muoi trong
X va hai kim
loai trong
Y Ian
li/cft
la:
A. Mg(N03)2; Fe(N03)2; Fe(N03)3 va Fe; Cu.
B.
Cu(N03)2; AgNOs; Fe(N03)3 va Ag; Cu.
C. Mg(N03)2; Fe(N03)3; Cu(N03)2 va Ag; Cu.
D.
Mg(N03)2; Fe(N03)2; Cu(N03)2 va Ag; Cu.
8
Gidi
Ro rang dap an can tim Id D. That vdy, ta
loai
trit
ngay
A, vi Fe vd Cu
trong
Y phdi tdc dung vai FefNOsJs
trong
X nen sau phdn ring
khong
the thu
dugc

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

toan thu diicfc dung dich X (gom hai muo'i) va chat
rfin
Y (gom hai kim
loai).
Hai muoi trong X la:
A.
Mg(N03)2
va Fe(N03)2 B. Fe(N03)2 va AgNOa
C.
Fe(N03)3
va
Mg(N03)2
' D. AgNOg va
Mg(N03)^_
Gidi
Chu y rdng rdn Y d day Id Ag vd Fe (dang bdi tap cho hdn hap kim
loai
vdo
dung dich gom hdn hap cdc
muoi
thi rdn thu
dugc
phdi Uu tien Id cdc kim
loai
CO
tinh khit yeu nhdt).
Do do di ddng
loai
trii cdc phitang dn B, C, D vd lua
chon

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

nhom
OH ditng ke nhau.
Loai triiD vi ddy la thi
nghiem
de chitng minh phdn tic
glucoza
c6
nhom
-CHO.
Vdy
chon
C.
4.
Cho phan ijfng : N2(k) + 3H2(k) < >
2NH3
(k); AH = -92 kJ. Hai bien phap
deu
lam can bang chuyen dich theo chieu thuan la
A.
giam nhiet do va giam ap suat. B. tang nhiet do va tang ap suat.
C.
giam nhiet do va tang ^p suat. D. tang nhiet do va giam ap suat.
Gidi
Loai trii A vi gidm dp
suat
thi can bdng se
chuyen
dich
theo
chieu

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

tocin
H a 2 ve.
.
Loai
trii
D vi
Xphdi chiia. nguyen
to K. Vdy
chon
C.
6. Cac polime thuoc loai tcf nhan tao la
A.
tot
visco;
ta nilon-6,6; tcf capron.
B.
tcf tam; tcf
vinilon;
tcf
visco.
C. ta nilon-6,6; ta capron; len
D.
ta
visco;
ta xenluloza axetat; ta dong-arnoniac.
(Dai
hoc 2012 - khoi B)
Gidi
Chii
y

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

Id ta
tong
hap, con ta
tdni;
len Id ta
thien nhien).
Vdy chon
C.
7. Trong cac polime: ta thm, scfi
bong,
ta
visco,
ta nilon-6, ta
nitron,
nhOTng
polime
CO
nguon go'c t\i xenluloza la
A.
ta tkm, sgi
bong
va ta
nitron
B. ta
visco
va ta nilon-6
C. sgi
bong,
ta
visco

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

hoan cac nguyen to hoa hoc, crom thuoc chu ki 4, nhom VIB.
(b) Cac oxit cua crom deu la oxit
baza.
(c) Trong cac hgp chat, so oxi hoa cao nhat cua crom la
-H6
(d) Trong cac phan
tfng
hoa hoc, hgp chat crom(III) chi dong vai tro chat oxi hoa.
(e) Khi phan ufng vdi khi CI2 dii, crom tao ra hgp chat
crom(III).
Trong cac phat bieu
tren, nhijfng
phat bieu dung la:
A.
(a), (b) va (e) B. (a), (c) va (e) C. (b), (d) va (e) D. (b), (c) va (e)
(Dai
hoc 2013 - khoi A)
to
Gidi
De y
rdng
b) Id
phdt
bieu
sai nen
loai
trie
ngay
A, C, D (CrO Id oxit
baza;

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

triing hgp nen
loai
trit
ngay
D, A, B. Vay
chon
C.
10. Cho can bang hoa hoc sau:
2SO2
(k) + O2 (k) < >
2SO3
(k) ; AH < 0
Cho cac bien phap : (1) tang nhiet do, (2) tang ap suat chung cua he phan
ufng,
(3) ha nhiet do, (4)
diing
them chat xuc tac V2O5, (5) giam nong do SO3,
(6) giam ap suat chung cua he phan ufng. NhOfng bien phap nao lam can bang
tren
chuyen dich theo chieu thuan?
A.
(2), (3), (4), (6) B. (1), (2), (4)
C. (1), (2), (4), (5) D. (2), (3), (5)
Gidi
Chu y
rdng
chat
xuc tdc (4)
khong
Idm can

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

hay yeu han so vai axit CH3COOH. Hay
dung
phiiang
phap
loai
trie nhu sau:
Vi
dung
dich
CH3CH2NH2
c6 moi
truang
baza
nen pH cua
dung
dich
ndy
phdi
Ian
nhdt
trong so 4
dung
dich. Vgy
loai
trii A, C.
NhiCng
dung
dich
NHoCH^COOH
c6 pH xdp xi Id 7, con

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

tinh Zn(0H)2, vdy loqi
tril
B. Do do dap dn can tim Id D.
13. Cho 1,37 gam Ba vao 1 h't dung dich
CUSO4
0,01 M. Sau khi cac phan uTng
xay ra hoan toan,
khdi
Itfcfng ket tua thu diicrc la
A. 3,31 gam B. 2,33 gam C. 1,71 gam D. 0,98 gam
(Dai
hoc 2013 - khoi A)
Gidi
De y rdng so mol Ba^* = so mol SO^ =0,01 mol
Do ket tua phdi c6 0,01 mol
BaSO^,
chua ke con
Cu(0H)2).
Vdy ta phdi cd
mket tua > 2,33 gam, nen loqi
trii
B, C, D. Vdy chon A.
14. Cho m gam rSn X gom Mg, Fe vao coc dtfng dung dich
CUCI2.
Sau khi phan
ufng
xong
dLfgc dung dich Y va ran Z. Them NaOH dvt vao dung dich Y, loc
ket
tua nung trong khong khi den khoi liJcfng khong ddi

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

Fe phdn
iCng
het thi long khoi liiang
magie
oxit va sdt oxit
tqo thdnh trong T phdi Ian hon tdng khdi liicmg Mg va Fe ban ddu, tOc m' > m.
Loqi
trii
C, do Fe con trong Z thi CuCl2phdi het, ddn den T khong the cd CuO.
Vdy chgn D.
15. Cho ran X gom Mg, Al, Zn va Fe vao dung dich
CuCl2
. Sau khi phan
ijfng
xong
Aiiac hon hgp ran Y va dung dich Z. Them dung dich NaOH da vao
dung dich Z thay xuat hien ket tua T. Nung T den
khdi
li/dng khong ddi
daac
h8n hop ran W. Vay ran Y gom:
A. Zn, Fe, Cu B. Mg, Al, Zn, Fe, Cu
C. Fe, Cu D. Zn, Cu
Gidi
Chu
y rdng thii tii phdn ling cua cac kim loqi vdi dung dich CuCl2 Id
Mg
>Al>Zn> Fe.
12
Vdy:

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

trai
sang phai, ban
kinh
nguyen tuf giam dan).
Ttfcfng tif
nhtf
tren, loai trCf D vi ban
kinh
nguyen
tijf
Si khong the \dn hcfn
ban
kinh
nguyen
tuf
Al.
Vay chon B.
17.
X la hon hop gom axit cacboxylic dcfn chufc A va axit cacboxylic nhi chufc B.
Dot chay hoan toan 0,15 mol X can viTa du x mol O2, sau phan ufng thu dtfcfc
0,40 mol CO2 va 0,25 mol H2O. Gia tri x la
A. 0,200 B. 0,375 C. 0,225 D. 0,325
Gidi
Ta
dung boo todn oxi de loai trie nhit sau:
0,4.2 + 0,25-0,2.2
- Loai trie A vi x = 0,2 thi so O trung binh - = 4,33 (vd li)
0,15
- Loai trilB vi x = 0,375 thi so O trung binh = ^'^"^ ^ 0,25—0,375.2 _ ^
0,15

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

O2,
sau phan ufng thu
diJOc
0,475
mol
CO2 va
0,325
mol
H2O.
Gia
tri
x la
A.
0,250
B.
0,350
C.
0,525
D.
0,475
Gidi
Ta
dung bdo todn
oxi de
loai
tril
nhiC sau:
- Loai trie
A vi x = 0,25
,

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
,

0,475.2
+
0,325-0,525.2
tni
so U
trung binn
- = 0,9
(v6
li)
0,25
Vqy chgn
D.
Liiu
y
Vi
A
chijCa
10; B
chiCa
20
trong phan tii nen tuang tU nhu bdi tren ta phdi cd:
1 <:
so O
trung binh
< 2
19. Hoa tan
hoan
toan
24
gam h6n hop

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.

Ca
(Dai
hgc 2013
-
khoi
B)
Gidi
Vi
dung dich
Y
chi chiia
mot
chat
tan
duy
nhdt
nen
H2SO4
dd ddng vita
du.
39,2.100
1
12
Theo
dc so
mol
HoSO.j
^77—7:— =
0,4 va
so

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

C vi M Id Zn cho ta he:
8 la + 99b + 125c = 24
a + b + c = 0,4
c = 0,05
- Loai
trii
D vi M Id Ca cho ta he:
56a + 74b + 100c = 24
a + b + c = 0,4
c = 0,05
Gidi
ra b < 0 (loai)
Gidi
rah < 0 (loai)
Vdy chgn A.
Liiu
y: Co the khong can dung da kien so gam hdn hap la 24 gam ud gidi
nhanh nhu sau:
Ggi a, b, c Idn
lugt
Id so mol MO, MCOH)^ vd MCO,, ta c6 he:
100.39,2
^
a + b + c = = 0,4
100.98
1,12
=
0,05
22,4
(M

+ 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.

CH3OH;
C2H5OH
B.
CH3OH;
C3H6(OH)2.
C.
C2H4(OH)2;
C3H5(On).3
D.
CH3OH;
C2H4(OH)2
Giai
Be y rdng hon hap X c6 so C trung binh
, 2n^,
2.0.25
, ,
trung binh = = ——-— =
l,OD
nen:
CO,
hh
1
0,6
=
1,66 = so
nhom
OH
hh
0,3
- Loai trie A (c6 so

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

Can phdi hieu rdng ancol HOCH=CHOH khong ben dd chuyen thdnh
andehit glycolic HOCH2CHO. Do dd este E phdi cd dang RCOOCH=CHOOCR,
tiic
E phdi cd so C chdn (loai
trit
A, B).
Mat
khdc vai cong thicc RCOOCH=CHOOCR thi E phdi cd it nhdt 3 n trong
phdn ti} (loqi
trit
D). Vqy chon C.
22. Dot
chay
hoan toan mot liicfng ancol X tao ra 0,4 mol CO2 0,5 mol H2O.
X tac dung
vdri
Cu(0H)2 tao ra dung dich mau xanh lam. Oxi hoa X bang
CuO tao hcfp
chat
hufu ccf da
chufc
Y. Nhan xet nao sau day
diing
v6i X?
A.
X lam mat mau nufdrc brom
B. Trong X c6 hai nhom -OH lien ket
voti
hai nguyen tuf
cacbon

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

khac
cho 0,3 mol X tac dung
vcJi
H2 dif (Ni; t°)
thay
CO
11,2 lit H2 (dkc) phan ufng. Hai andehit da cho la:
A.
HCHO; CH3CHO B. CH3CHO; C2H3CHO.
C. HCHO;
(CH0)2
D. HCHO; CH2(CHO)2.
Gidi
, . - . "co, 1
Be y rang hon hap X cd so C trung binh = ^ = = 1,66 = so lien ket n
,. , "H, 0,5 , ^
trung
bmh -—^ = = 1,66 nen:
"hh
16
- Loai tritA (c6 so n trung binh Id 1).
- Loai trie B (c6 2 <so C trung binh < 3).
- Loai trie D (c6 so n trung binh khdc so C trung binh).
Vdy chon C.
24.
Cho h6n hgp X gom hai axit
cacboxyUc.
Dot chay hoan toan 0,3 mol hon
hgp X, thu
di/gc

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.

HCOOH
va
C2H5COOH
B. CH2=CHC00H va
CH2=C(CH3)COOH
C.
CH3COOH
va
C2H5COOH
D.
CH3COOH
va
CH2=CHC00H
Gidi
2n^
Q 2.0,2
Ta
CO
so H trung binh — = — = 4, vdy loai trie B, C.
Boo toan O cho so mol CO2 =—— ^ = 0,24 mol, vdy loai trie A (do
A gom 2 axit cacboxylic dan chiCc no khi chdy phdi too so mol CO2 = so mol H^)
Vdy chon D.
26.
Hidro hoa hoan toan 0,05 mol hon hgp X gom hai
an
debit can 2,24 lit H2
(dkc). Mat khac, khi cho cung lifgng X tren phan ufng
vdri
mot lugng dtf dung
dich

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

ket n
trung binh
= —^ = = 2 nen
loai
trii
B, C.
0^05
Mat khdc
so
m.ol.
Ag - 0,16 nen nx :
/i.Ag
^ 1
•
3,2
tiic phdi loai trie
A.
Vqy chon
D.
27.
Cho
0,025
mol h6n hop X gom hai
andehit
c6
khoi lucfng
1,64 gam
phan
urng
vdi

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
=

0,08 nen ux :
nAg
= 1 : 3,2
ti'Cc
phdi loai
trii
A, B.
1
64
Mai
khdc phdn
til:
lugng trimg binh
cua hSn hap - -^^—^ 65,6 nen
phdi
loai trit
C. Vqy
chgn
D.
28
Ii6n
hcfp
X gom hai
axit
cacboxylic
dcfn chijfc, mach
hd, ke
tiep nhau trong
cung
day

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.

C. C2H5COOH
va
C3H7COOH.
D. CH3COOH va
CallsCOOH.
(Dai
hoc 2013 -
khoi
B)
Gidi
Ta
CO
so mol 2
axit trong
10,05 gam hon hap -
—10,05
^
Q
,nol
22
nen phdn
td
luang trung binh
2
axit
~
=^80,4.
Vdv
loai trie
A, D.

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

gom C,
II,
O (My. < My). Cho 0,1 mol h6n hop gom X va Y phan uTng hoan
toan vdi l)icmg du' dung dich AgNOa trong NH3, thu difcfc
38,88
gam Ag.
Phan
tram
khoi
\\igng
cua X trong h6n hcfp M la
A.
83,33%
B.
66,87%
C.
75,00%
D
90,00%
Gidi
Ta CO so mol Ag = 0,36 nen nx " riAg = 1 : 3,6.
Vdy hdn hap phdi gom HCHO(X) vd
RCHO(Y).
Goi
X,
y Idn lugt Id so mol
ciia
X, Y, ta c6 he:
x-hy = 0,l x = 0,08
4x +

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

- Do ddp an can tim Id B nen ta cd
M
„ = = 60
0,02
Vdy Y la HCOOCH3.
30. Hon hcfp M gom andehit X (no, dcfn
chuTc,
mach hd) va hidrocacbon Y, c6
tong so' mol la 0,2 (so' mol cua X nho hon cua Y). Dot
chay
hoan toan M, thu
dugc 8,96 lit khi CO2 (dktc) va 7,2g H2O. Hidrocacbon Y la
A. CH4 B.
C2H2
C.
C3H6
D.
C2H4
(Dai
hoc 2010 - khoi B)
Gidi
Vi
so mol HoO = so mol CO9 - 0,4 nen Y Id anken, vdy loqi
trii
A,
B.
19
Cung phdi loai trit C, vi neu Y Id
C3H6
thi X budc phdi Id HCHO (do so C

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

Vay chon D.
32.
Dot
chay
hoan
toan h5n hgp X gom
C2H2,
C3H4
va
C4H4
(so' mol moi chat
bang
nhau) thu duac 0,09 mol CO2. Neu lay
cung
mot liigng h6n hgp X nhi/
tren
tac dung vdi mot liigng dii dung dich
AgNOa
trong NH3, thay sau mot
thdi
gian khoi \Mng ke't tua thu diigc Idm hern 4 gam.
Cong
thufc cau tao cua
C3H4
va
C4H4
trong X Ian luat la:
A. CH^C-CH3, CH2=CH-C=CH. B. CH^C-CHa,
CH2=C=C=CH2.
C.

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

+
159.0,01
- 3,99 gam < 4 gam.
Vay chon A.
Litu
y
Vai nhffng bdi toan xudt hien tinh hud'ng cho hSn hgp A tdc dung vai
chat
B,
nhdn
thdy
"sau mot thai gian luang ke't tua thu duac dd vuat qud x gam" hay
"sau mot thai gian luang khi thu duac dd vUat qua y lit", thi tat cd cdc
chat
trong hon hgp A deu cho dugc phdn ling vai
chat
B. Van dung dieu ndy c6 the
chon
ngay
ddp dn can tim Id A md khong can thong qua tinh toan nhu tren.
33.
X la hon
hcfp
gom 2
ancol
no,
mach
hd. Dot
chay hoan toan
X

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 "

1 •
So
C
truns binh
= ^ = = 2,66 nen
loai trit
A.
0,15
2
0 125
So
nhom
OH
trung binh
= ^ = = 1,66 nen
loai tril
B
0,15
Cung loai tril
C vi hdn hap CH3OH; C3H5(OH)3 c6 so C
trung binh
= so
nhom
OH
trung binh.
Vqy chon
D.
34,
X la h6n hop gom
C2H2

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.

Tiep
theo loai trie
A, C do hdn hap dd cho c6 so C
trung binh
Id — = 2.
3
Vqy chon
D.
0,4
21
O
CHI/ONG
II
KY
THCI^T
DUNG
CfiC
DjNH
lUQT
B^OTO^N
Trong Hoa hoc, c6 4 dinh luat bao to^n thiforng
dugc
stir dung la: Dinh luat
bao toan khoi li/cfng; Dinh luat bao toan dien
tich;
Dinh iuat bao toan electron
va Dinh luat bao toan nguyen to. Tat nhien khi da
sijf
dung cac dinh luat bao
toan thi hau nhu khong can viet cac phiiong

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

chat
hoa hoc
tiiong
ixi tac dung v6i cijng mot chat,
nhif
hon hop kim loai
hoac
h6n hop oxit kim
loai
tac dung vcfi axit HCl;
Ii2S04
; hon hcfp axit
cacboxylic
dcfn chijfc tac dung
vcfi
baj^a, vcfi ancol; h6n ho'p cac muoi
cacbonat
tac dung vdi axit Dac biet dinh
luat bao toan khoi lU'cfng to ra la mot
ccng
cu hieu qua
Idii
di/oc dung kem
vdri
dinh
luat bao toan nguyen to de giai cac bai toan oxi hoa
khijf
phufc tap.
21
Dinh

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

luat
bdo
toan
nguyen
to
Dinh
luat nay dac biet thich hgp vdi cac bai toan gom nhieu qua
trinh
phan
L'ng,
trong do san pham tao thanh c6 cung so' nguyen tii cua mot nguyen to'
trong
phan tuf (nhu' tao hon hgp NO; NO2 hay hon hgp Ng; N2O),
hoac
bai toan
CO
cac phan ufng ma san pham tao ra tuan theo mot qui luat xac dinh
vdri
so
22
nguyen
t>jf
cua mot nguyen to trong phan tuf chat phan uTng,
nhtf
h6n hop cac
axit
cacboxylic
tac dung vdi lifgng dtf NaHCOa thi axit
cacboxyhc
don

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

tam
den mufc oxi hoa cr cac giai doan
trung
gian.
Can biet them rSng sii phan loai cac ufng dung
tren
chi c6
tinh
tiiong doi, vi
mot bai toan Hoa hoc c6 the giai theo nhieu
each
khac nhau, m6i
each
lai c6
the van dung dinh luat nay
hoac
dinh luat Idiac, tham chi van dung nhieu dinh
luat
cung luc. Van de la
each
nao cho ket qua nhanh
chong,
va quan trong hon
ca la
each
nao giup ta hieu bai, nam bai to't nhat.
Tuy
CO
4 dinh luat bao toan, ta hay xet 14 vi du
diidi

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

= 16 +
98.0,3
-
0,3.18
= 40 gam
+
Diing dinh luat bao toan dien
tich
Vay
mmi,6i
=
nikim
loai
+
n^so:-
=
mx - m^^, + m
- 16 -
0,3.16
+
96.0,3
= 40 gam.
Vdy chon C.
23
Vi
du 2: Cho m gam Fe vao binh chiJa dung dich gom H2SO4 vk HNO3, thu
difoc
dung dich X va 1,12 lit khi NO. Them tiep dung dich
H2SO4
dii vao

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

sau phan
ijfng.
- Khong dung dinh luat bao toan dien
tich
do khong c6 sir thay the" ion nay
bang mot ion khac trong bai toan.
- Khong dung dinh luat bao toan nguyen to do cung khong c6 dau hieu dac tnfng.
•
Gidi
+
Dung dinh luat bao toan electron
De y
rkng
Fe cuoi bai da bi oxi hoa toan bo thanh Fe^^; Cu cudi bai bi oxi
hoa thanh Cu^* va N^^ cudi bai bi khuf thanh N*^
Tdng sd mol NO 0,05 + 0,02 = 0,07; Sd mol Cu =
0,0325
Fe
CHO
-> Fe^2
a mol
Cu ^ Cu
+2
+
2e
2a mol
+
2e
0,065mol
N

+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

y mol
HNO3.
Sau phan ufng thu dilcfc V lit (dkc) hon hcfp NO; NO2 (khong
con san pham khuf khac). Bieu thufc quan he giufa y theo x va V la
A. y - lOx + 5,6V B. y = 6x + 2,8V
V
„ . V
C. y = lOx +
22,4
D.
y = 8x +
22,4
24
•
Nhdn
xet
-
Khong dung dinh luat
bao
toan dien
tich
do
khong
c6
sif
thay the"
ion nay
bang
mot ion
khac trong

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

+
"N/NO,
<=>
y =
3x
+
2.2x
+
3x
+
= lOx
+
22,4
.
Vdy
chon
C.
22
A
+
Dijng dinh luat
bao
toan electron
Gia
sit
h6n hcfp
khi gom
a
mol
NO va b

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
+

b
=
22,4
<^
3a
+
b
=
lOx
1
V
a
=
-(10x
)
2
22,4
1
3V
b
= -(^ lOx)
2
22,4
1
V 1 3V
Vay
n,„„^=4n,„+2n,„^«
^ =
'^2^^^''"
22:4^''^2

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^

+
lOn^
„ +
10n^„^^„
+
Ta
dung
bao
toan
N vi cac
khi
NO va NO2 c6
cung
so
nguyen
tuf
N
trong
phan
tijf.
+ Neu
de
cho hSn hop khi thu
dtfcfc
la V
lit (dkc) hon hop gom
NO va N2O,
bai
toan
bat

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"^^

da
nhan
(3a
+
8b) mol
electron
de
tao
khi,
ta
c6 he:
25
a + b =
22,4 <!
3a + 8b = lOx
5 22,4
1
3V
b
=
-(10x ^^—)
5 22,4
Vay
n,„,,^
=4n,,. +
l0n,„«>
y
^4^(^-IOx)
+10^(10x
V

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

Gidi
+ Dung dinh luat bao toan dien
tich
De y rang JM^. = 14 thi %N = 11,864
Nen M =62 cho % NO, = —-^— = 52,54
14
tuTc n
14,16.52,54
= 0,12 mol.
100.62
Chu
y rang m gam ran thu du'cfc la cac oxit nen:
0,12
=
7,68(gam)
m
-
mk„„
+ m^, - (14,16 - 62.0,12) +16 ^
Vay chon B.
+ Dijng dinh luat bao toan electron
, , , 14,16.52,54
Tucfng tu
nhii
tren ta co n = =0,12 mol. ,
^•0' 100.62
Vi
san pham la cac oxit kim loai, NO2 va O2 nen N^^ da nhan electron tao
N^^ va O"^ da cho electron tao 0° theo cac qua
trinh

cho nhan electron sau:
26