D. chuyd'n tir mau da cam sang mau xanh luc.
Hu&ng đn gidi
PTHH xay ra:
K2Cr207 + 2 K O H -> 2K2Cr04 + H2O
kali dicromat kali cromat
(da cam) (vang)
Dap an dung la C.
Khi cho dung djch NaOH vao dung djch K^CrjO, thi dung djch tir Ạ mau da cam chuyen thanh khdng mau
B. mau vang chuyd'n sang mau da cam. C. kh6ng mau chuyd'n sang mau vang D. mau da cam chuyen sang mau v^ng
Hu&ng đn gidi
PTPU: K 2 C r 2 0 7 + 2 N a O H - » K 2 C r 0 4 + N a 2 C r 0 4 + H 2 0 da cam vang vang
' dung djch chuyen tir mau da cam sang mau vang.
Dap an dung la D.
Chd v;
Cr20^- + 2 0 H - ?=± 2CrÔ- + H2O *
da cam vang
Khi them OH": Da c a m - > Vang K j b : i
Khi them H * : Vang -> Da cam
8. Ion M^* C O ca'u hinh electron phan \6p ngoai cung 3d'. Hay chon phat bi^u
khongdiing?
Ạ M C O ca'u hinh electron la 1 s-2s-2p*3s-3p*3d*
B. Hidroxit ciia M'"^ c6 tinh luong tinh
C. Dung djch chira M ' * vira c6 tinh oxi hoa, vira c6 tmh khir ^ D. M thu6c chu k i 4, nhom VIB.
w Hu&ng đn gidi X«.,i '•>' ) X«.,i '•>' ) 1 X 0 5:. r' Suy ra: M ' V ls-2s-2p'3s-3p''3d\ M :ls22s22p^3s23p°3d'*4s^(Z =24;Cr) Suy ra: ^
- Cr(OH)3 C O tinh ludng tính:
Cr(OH)3 + 3HC1 ^ CrCl, + SHjO Cr(OH)3 + NaOH ^ Na [Cr(OH)4
- Ion Cr^* vira c6 tinh oxi hoa vita c6 tinh khu: 2Cr''++Zn->2Cr^++Zn2^
2Cr^* + 16KOH + 3 B r 2- > 2 C r 0 4 " + 6 B r + 1 6 K ^ + 8 H 2 O
Dap an dung la A .
9. Phat biéu khong dung la:
Ạ Cac hop chat Cr.O,, CitOH),, CrO, CKOH), dau c6 tinh chit luong tinh.
B. Hop chA Cr(n) c6 tinh khir dac trimg con hop chat Cr(VI) c6 tinh oxi hoa manh. C. Cac hop chat CrO, CrCOH), tac dung diroc \6i dung djch HCl con CrOj tac
dung diroc vori dung dich NaOH.
D. Them dung djch ki^m vao mudi dicromat, mu6'i nay chuyS'n thanh mu6'i cromat.
Huang dan gidi
Xet cac phirong an:
Ạ Khdng diing, vi chi c6 CuÔ, CrCOH), (crom c6 s6' oxi hoa + 3) c6 tinh luong tinh; con CrO, CrCOH), c6 tinh bazo (khong th^ hiSn tinh axit).
Thidu: Cr(OH)3 + 3HC1 > CrClj + SH.O
Cr(OH)3 + NaOH ^ Na[Cr(OH)4].
B. Dung. D6'l voi cac hop chat ciia crom: - Co sd oxi hoa +2: Tinh khir.
- Co sd oxi hoa +3: VCra c6 tinh khir, vCra c6 tinh oxi hoạ - Co sd oxi hoa +6: Tinh oxi hoa manh
Thi du: 2CrCl, + CI, > 2CrCl3
K . C r A + 14Ha > 3C1, + 2KC1 + ZCrCl, + TH^O C. Diing. Ddi vdi cac oxit, hidroxit ciia crom:
- Co sd oxi hoa +2: Co tinh bazo - Co sd oxi hoa +3: Co tinh ludng tinh - Co sd oxi hoa +6: Co tinh axit
D. Diing: CrÔ + 2H" < = ± C r . O / ' + H^O
rromat dicromat Khi tham k i l m ( O H ) thi H" + O H ' > H^O,
=> [H*] giam => can bang trdn chuy^n sang trai, tire Ik mudi dicromat se chuyen thanh mudi cromat.
Dap an dung la A .
CtyTNHHAf/\ VH KhangVie!
10. Khi cho 41,4 gam h6n hop X gdm FẹO,, Cr.Ọ, va A I 2 O 3 tac diing vdi dung djch NaOH dac (du), sau phan ling thu duoc chat ran c6 khdi luong 16 gam. Dé djch NaOH dac (du), sau phan ling thu duoc chat ran c6 khdi luong 16 gam. Dé khiJr hoan toan 41,4 gam X bang phan ling nhiSt nhom, phai dung 10,8 gam A l . Thanh phdn phin tram theo khdi luong cua CrjO, trong hdn hop X la (cho hidu suát cua cac phan ihig la 100%)
Ạ 36,71%. B. 50,67%. C. 66,67%. D. 20,33%.
Huomg đn gidi
Goi X , y, z Idn luot la sd mol FêOj, Cr.Oj, AUOj trong hdn hop X. v
Theo bai ra ta cd: 160x + 152y + 102z = 41,4 (1) • X + NaOH (dac, du):
FêOj + NaOH > Khdng xay rạ I . .
Cr,03 + 2NaOH + 3 H, 0 > 2Na[Cr(OH)4] A I 2 O 3 + 2NaOH + 3H2O > 2Na[Al(OH)4]
=> 160x= 16 =:> x = 0,l (2) • X + A l :
FêO, + 2A1 > 2Fe + AlA
X 2x C r A + 2Al >2Cr + Al,03 V 2y Ta cd: 2x + 2y = 0,4 ( 3 ) Tir(2,3) z i > y = 0,l ; x = 0 , l . - Thay v a o ( l ) => z = 0 , l . %m(Cr,03) = 152. 0,1 /41,4 = 36,71 %. Dap an dung la A .
11. Hoa tan het 20,6 gam Cr(OH)3 trong 500 ml dung djch HCl 2M dun ndng, thu duoc dung djch X. Khdi luong Zn phan ling vira het cac ch& trong dung djch X la duoc dung djch X. Khdi luong Zn phan ling vira het cac ch& trong dung djch X la Ạ 19,5 gam B. 32,5 gam C. 6,5 gam D. 13 gam
Hu&ng đn gidi
Theo bai ra: n^^^^^^^^ =0,2(mol); n^^x = K"""')
PTPIT: Cr(OH)3 + ^HCl -> CrClj + 3H2O
Banđu: 0,2 1 i Phan ling: 0,2 0,6 -> 0,2 ' C 6 n : 0 0,4 0,2 Zn + 2HC1 ^ Z n C l 2 + H2 0,2 < - 0,4 (mol) Zn + 2CrCl3 -> ZnClj + 2CrCl2 0,1 < - 0,2 (mol) . :>!j i
Phdn logi va phucfngphdp gicii nhanh tSl Hoa hoc iz -L-U 1 Htinn 1 oun
=> =0,2 + 0,1 =0,3(mol) => m^^ =0,3.65 = 19,5(gam)
Dap an dung la A
12. Trong pin diSn hoa Cr - Sn xay ra phan ihig: ... Cr + ... Sn-" > ... Cr^* + ... Sn ... Cr + ... Sn-" > ... Cr^* + ... Sn
Biét E ° 3^ = - 0,74 V. Suát dien d6ng chuin cua pin didn hoa Cr - Sn \k
A . - 0 , 8 8 V . B . - 0 , 6 0 V. C. 0,60 V . D. 0,88 V.
Hu&ng đn gidi
- V I Epi„ lu6n ducmg => loai phirong an A B. - V i Cr C O tinh khif manh hon Sn ntn
E V - S n ) = E ° S i i / S n ~ E ° C r /Or = E°s„ /Sn ~ ( ~ 0.74) = + 0 , 7 4 ( V ) .
- Vi Sn diing tnttSc H trong day dien hoa ndn E^ạ^'^/s, < 0 . Dod6E°(Q.^)<0,74V.
Dap an dung la C.
13. Hiat bid'u nao sau day khong diing khi so sanh tinh chtft hoa hoc cua nh6m va crom? Ạ Nhom va crom đu bj thu d6ng hoa trong dung dich H2SO4 dac ngu6ị Ạ Nhom va crom đu bj thu d6ng hoa trong dung dich H2SO4 dac ngu6ị B. Nhom va crom d^u b^n trong kh6ng khi va trong nirdc.
C. Nh6m va crom đu phan ling vdi dung dich HCl theo cung ti Id v^ s6' mol. D. Nh6m C O tinh khir manh hon crom.
Hu&ng đn gidi
Nh6m va crom phan utig vdi dung dich HCl theo ti Id khac nhau: 2A1 + 6HC1-).2A1C13+3H2
Cr + 2HC1 ->CrCl2+H2
Phat bi^u kh6ng dung la C. Dap an dung la C.
14. Hidn tuong xay ra khi nho vai giot dung djch H2SO4 v^o dung djch Na2Cr04l& Ạ dung djch chuyd'n tir mau vang sang khdng maụ Ạ dung djch chuyd'n tir mau vang sang khdng maụ
B. dung djch chuy^n tCr mau da cam sang mau vang. C. dung dich chuyd'n tiir mau vang sang mau da cam. D. dung djch chuy^n tCr khdng m^u sang mau da cam.
Hu&ng đn gidi
PTHH: ' 2Na2Ci04 + H2SO4-> Na2Cr207 + Na2S04 + H2O
mau vang mau da cam
Dap an dung la C.
15. Khi cho hoa chat X vho tac dung vdi NaOH dir c6 sSn C r Q j thi sau phan ling, dung djch thu duc«c c6 mau vang. Trong s6' cac chat: dung djch thu duc«c c6 mau vang. Trong s6' cac chat:
Cl2,S03,03,H202,Bl2,HCl,K2C03 ; . ; , y ; ;
S6' hoi chat thoa man vdi di^u kidn ciia X la . •
Ạ 7 B.6 C. 5 D.4 ?;
Hu&ng đn gidi ,
So d6: X + NaOH + C r C ^ -> Na2Cr04 +NaCl + ...
(mau vang) mi ị 1 : ns.: >
=> X la chát oxi hoa manh trong m6i trirdmg ki^m " " '* ' => X C O tb^ la a,, O3, H2O2, Br2 (4 chat) Dap an dung Ik D.
Chit v.- PTHH xay ra:
3CI2 + 16NaOH + 2CrCl3-> 2Na2Cr04 + 12NaCl+ 8H2O 3O3 + lONaOH + 2CrCl3 -> 2Na2Cr04 + 6NaCl + 3O2 + SHjO
3H2O2 +10NaOH + 2CrCl3 ->2Na2Cr04 + 6 N a a + 8H20 " ' '
3Br2 +16NaOH + 2CrCl3 -> 2Na2Cr04 + 6NaCl + 6NaBr + 8H2O
15. Khi thdm vai giot axit clohidric vao dung djch natri cromat, hi6n tifong xay ra la Ạ dung djch chuyd'n tCr mau da cam sang mau vang. Ạ dung djch chuyd'n tCr mau da cam sang mau vang.
B. dung djch chuyd'n tir mau vang sang mau da cam.
C. tao ra ket tiia axit cromic mau dọ * '
D. tao ra dung djch mu6'i crom (III) clorua mSu xanh. (
Hu&ng đn gidi
Khi cho HCl vao Na2Cr04 (mau vang), xay ra qua tfmh:
2CrÔ" + 2H* < > CrjÔ- +H2O
(m^u vang) (mau da cam) ^ => dung dich chuy^n tir mau vang sang mau da cam.
Dap an dung la B.
Dang 2; Bai tap s^t tac dung vdi axit HNO3
1. Hoa tan hoan toan 11,2 gam Fe vao dung djch HNO3. Sau khi cac phan ung kd't thiic thu duoc 3,36 lit khi NO (0 dktc, san p h ^ khir duy nhát) va dung djch thiic thu duoc 3,36 lit khi NO (0 dktc, san p h ^ khir duy nhát) va dung djch chiia 2 mu6'ị Khi c6 can dung djch X thu duoc khoi luong mu6'i khan la
Ạ 27 gam. B. 28 gam. C. 39,1 gam. D. 54 gam.
Hu&ng đn gidi
Theo hk\: 0^ = 11,2/ 56 = 0,2 (mol).
HNO = 3,36/ 22,4 = 0,15 (mol).
PTPlT: Pe + 4HNO3 ^ Fe(N03)3 + NO + 2H2O '
Fe + 2Fe(N03)3 > 3Fe(NO,,),
( 0 , 2 - 0 , 1 5 ) ^ 0,1 0,15 (mol) Vay, sau khi cac phan ting xay ra hoan toan c6:
0,15 mol FeCNOj), ; i:> 5o»Ux'
0,15 - 0,1 = 0,05 mol FeCNO,), ' =>m^„,i = 0,15. 180 + 0,05.242 = 39,1 (g).
Dap an dung la C. 2. Hoa tan 11,2 gam Fe bang dung djch HNO3, sau khi cac phan ilng xay ra hoan
toan thu duoc h6n hop san phim khir (gom NO,, NO, NjO va N,), dung djch X va tháy ccn lai 2,8 gam Fẹ Khi c6 can dung djch X thu duoc m gam muoi khan. Gia tri cua m la
Ạ 27 gam. B. 28 gam. C. 36,3 gam. D. 54 gam.
Hu&ng din gidi
112 — 2 8
Theo bai ra: mp^ (p^j,, —' = 0,15 (mol).
VI Fe du, ndn sau khi cac phan ling xay ra hoan toan chi thu diroc FeÔO,),: Fe """"-^ > Fe(N03),
vay m„„«i = 0,15.180 = 27 (gam)
Dap an dung la Ạ 3. Hô tan hoan toan m gam Fe vao 0,2 lit dung dich HNO3 I M , phan ting tao ra
san ph^m khu duy nhát la NỌ Gia tn 16n nhát cua m la
Ạ 2,8 gam. B. 5,6 gam. C. 8,4 gam. D. 4,2 gam.
Hu&ng dan gidi
Theo bai ra: nHN0 3 = 0,2. 1 = 0,2 (mol).
PTPLT: Fe + 4HNO3 > Fe(N03)3 + NO + 2H,0 0,05 < - 0,2 ^ 0,05 (mol) Fe + 2Fe(N03)3 ^ 3Fe(N03), 0,25 mol <r- 0,05 (mol) vay m , ^ , _ , = (0,05 + 0,025). 56 = 4,2 (gam) Dap an dung la D. 4. Cho m gam b6t Fe tac dung hd't vdrj dung djch HNO3 loang, thu duoc dung djch
X va khi NO (san ph^m khu duy nha't). C6 can dung djch X thu duoc 51,2 gam mudi khan. Bid't rang s6' mol Fe ban đu bang 31,25% s6' mol HNO3 phan utig. Gia tri cua m la
Ạ 20.72 B.28 C. 10,36 D. 14.
Hu&ng dan gidi
PTPU": Fc + 4HNO3 ^ Fe(N03)3 + NO + 2H2O
Cty TNHH AfTV DVVH Khang Viet
Na'u chi xay ra phan trfin thi n pe / "H N O J = 1 / 4 = 0,25 = 25%. Theo bai ra, n /np,N03(p/u)= 31,25% => c6 them phan irng:
Fe + 2Fe(N03)3 3Fe(N03)2 :
Goi X la s6' mol HNO3 phan ling => s6' mol Fe la 0,3125x. PTPLT: Fe + 4HNO3 Fe(N03)3 + NO + 2H3O
x/4 X -> x/4
Fe + 2Fe (NOj), ^ 3Fe(N03),
(0,3125x-0,25x) 0,125x 0.1875x Ta c6: (0,3125x - 0,25x).242 + 0,1875x. 180 = 51,2
=> 64x =51,2 => x = 0,8 vay m = 0,3125. 0,8. 5 6 = 14 (gam)
5. Nung m gam bot sat trong oxi, thu duoc 3 gam h6n hop chat rdn X. Hoa tan het h6n hop X trong dung dich H N O 3 (du), thoat ra 0,56 lit ( 0 dktc) NO (la san h6n hop X trong dung dich H N O 3 (du), thoat ra 0,56 lit ( 0 dktc) NO (la san ph^m khir duy nhát). Gia trj ciia m la
Ạ 2,62. B. 2,32. C . 2,52.
Hu&ng đn gidi
Dap an dung la D.
D. 2,22.,
Theo biii ra: n^o = 0,56
22,4 = 0,025 (mol) Taco: :^-^ = ^ + 3.0,025: 56 8 => 10m = 25,2 => m = 2,52. •3m = 2 1 - 7 m + 4,2 Dap an diing la C ,
Dang 3: E ai tap sat tac dung voi axit H 2 S O 4
1. Cho 6,72 gam Fe vao dung djch chiJa 0,3 mol H 2 S O 4 dac, nong (gia thiet S O , la san phdni khiJf duy nha't). Sau khi phan ung xay ra hoan toan, thu duoc san phdni khiJf duy nha't). Sau khi phan ung xay ra hoan toan, thu duoc
Ạ 0,03 n o l Fe,(S04)3 va 0,06 mol FeS04. 'r
B. 0,02 mol Fe,(S04)3 va 0,08 mol FeS04. C. 0,12 mol FeS04.