3m 3 - m
- + 3.0,025 56 8
=> 3m = 2 1 - 7 m + 4,2=> 10m = 25,2 =>m = 2,52. ;
Dap an dung la C. 4. Cho 5,6 g?m b6t Fe tac dung vdi khi oxi thu duofc 7,52 gam h6n hop ran X. Cho
h6n hop ran X tac dung voi dung djch HNO3 (du), thu duoc V lit khi NO (san ph^m khii duy nhát, o dktc). Gia trj cua V la
Ạ 0,448. B. 0,224.
Huong đn gidi
5,6
C. 4,480. D. 2,240.
Theo bai ra: np^ = — = 0,l(mol)
56 mo = 7,52-5,6 = 1,92 (gam) I 92 no = 16 = 0,12(mol) 0 Taco so d6: Fe - 3e Fe 3+ 0,1 0,3 (mol) 247
Fe Fe(N03)3 p o B o + n O t + X FeO, FejOj, Fe304, Fe X Ta c6: 0,3 = 0,24 + 3x => 0,06 = 3x => x = 0,02. Vay VNO = 0,02. 22,4 = 0,448 (lit).
Dap an dung la Ạ 5. Ti6n hanh phan ling nhifit nh6m 10 gam h6n hop X g6m A l va FejOj (trong dieu
kifen kh6ng c6 kh6ng khQ, thu duoc h6n hop Y g6m Fe, Fe304, FeO, Fe203 va A l . Cho Y tac dung vdi HNO3 loang, du, thu duoc 2,24 lit khi NO (san phdm , khu duy nhát, d dktc). PhSn tram kh6'i luong cua Fe.O, trong X la
ÍẠ 72%. B. 73%. C.64%. D. 50%.
Huong dan gidi
Goi X, y 1 ^ luot la s6' mol A l va Fe203 trong X.
Taco: 27x+ 160y= 10. — Ta CO so 06: 0 A l - 3 e 3+ A l X 0,3 (mol) 0 +3 Al,FeiÔ
Fe, Fe304, FeO, Fe^Oj, A l / 2,24
Theo bai ra: nNo = —— = 0. l(mol). 22,4
Do do, ta c6: Ze (cho) = 3x.
Ze (nhan) = 0,1.3 = 0,3 (mol). => 3x = 0,3 x = 0 , l .
=>mA, = 0,1.27 = 2,7(gam).
=> m Fe203 = 10 - niA, = 10 - 2,7 = 7,3 (gam)
V a y % m p, 2 0 3 = ^ - 1 0 0 = 73%. ' +3 +3 > Al,Fe <N 0 ' t i u + 0" Dap an dung la B. 248
6. Cho 13,12 gam h6n hop X g6m Fe, Fe304, FêOj vao dung djch HNO3 loang, du thu duoc san ph^m khu gom hai khf NO, N.O c6 the tfch V lit (dktc) va c6 ti thu duoc san ph^m khu gom hai khf NO, N.O c6 the tfch V lit (dktc) va c6 ti
kh6'i so voi H , la 18,5. Mat khac náu cho ciing luong X tren tac dung vdi khi CO du thi sau khi phan iJng hoan toan thu duoc 9,8 gam Fẹ Gia trj ciia V la:
Ạ 0,448 B. 3,136 ' C. 2,24 D. 3,36
Huong đn gidi
Taco sod6 sau: >
mjo] - 13,12 - 9,8 = 3,32 ( g ) ^ njoj = 0,2075mol np^ = 9,8/56 = 0,175mol
Qua trinh cho - nhan electron: Fe ^ Fe-^^ + 3e 0,175-> 0,525(mol) O + 2e ^ Ô" 0,2075^ 0,415(mol) ' +5 +2 N + 3e -> N 3 x < - X +5 +1 2 N + 2.4e N2 •fhi(, 8y < - y =>0,415-'-3x + 8y = 0,525=>3x + 8y = 0 , l l ( l )
Mat khac: ^^^ilily = 18,5.2 = 37 x + y
= > 7 x = 7 y = > x = y (2)
Tir(1.2) ^ x = y = 0,0! > "
Vay V = (x + y).22,4 = (0,01 + 0,0l).22,4 = 0,448(^)
Dap an dung la Ạ
^ang 16; Bai tap ve phan umg cua h6n hgfp FeS; va CuzS vdi axit HNOj
1. Hoa tan hoan toan h6n hop g6m 0,12 mol FeSj va a mol Cu^S vao axit HNO3
(vira du), thu duoc dung djch X (chi chiia hai mu6'i sunfat) va khi duy nhát NỌ Gia trj cua a la
Ạ 0,04. B. 0,075. C.0,12. D. 0,06.
Hudng đn gidi
Ta C O so d6:
2FeS3 -H cu,s > Fe,(sọ)3-HCusọ
0,12 (mol) ămol)
^ a = 5 : 1 ^ = 0,06(mol). , , » a p a" dung la D.
2.. Hoa tan hoan toan h6n hop g6m FeS, 0,24 mol va Cu,S vao dung dich HNO3 viJa du thu duoc dung dich X (chi chiia hai mu6l sunfat) va V lit khf NO duy nMt. Gia trj cua V (dktc) la Ạ 34,048 1 ' " ' B. 35,84 C. 31,36 D. 25,088 ' ' ^ Hudng đn gidi So do phan ufng: 2 F e S 2 - > F e 2 ( 5 0 4 ) 3 + 5 0 ^ ' 0,24 ^ - ' 0,12(mol) Cu2S- > C u S 0 4+Cu2-' .„5j,^ X (mol) Cu^^+SOi" ->CuS04 X =>x=0,12 (mol)
Qua trinh nhircfng, nhan electron:
+2 -1 +3 +6 ^eS2 ^ F e + 2S+15e ^eS2 ^ F e + 2S+15e 0,24 -> 3,6(mol) +1 - 2 + 2 + 6 CU2S - ^ 2 C u + S + lOe 0,12 l,2(mol) => T6ng s6' mol electron cho: 3,6 +1,2 = 4,8(mol)
N + 3 e - > N ( N 0 ) ' ^ 4 , 8 - > l , 6 ( m o l )
= > V N O = 1,6.22,4 = 35,84(1) Dap an dung la B. 3. Hoa tan het m gam h6n hop FeS. va CụS trong dung dich HNO3, sau cac phan
ling hoan toan thu duoc dung dich X chi c6 2 chat tan. vdri t6ng khoi luong cac chat tan la 72 gam. Gia tn cua m la:
Ạ 60 ' B.40 C. 20 D. 80
Huong đn gidi
Vi chi thu dirac hai chat tan trong dung djch sau phan ling Hai chat tan do la
CUSO4 va FCJCSOJ,: . S j j i . ' ) .ri
Sd d6 phan iJng:
2FeS2 + CujS -> Fe2 ( 8 0 4 ) 3 + 2CUSO4 , ,
2x < - X ^ X 2x (mol) -h/.,''...,,>
Theo bai ra: 400.x + 160.2x - 72 => 720x = 72 => x = 0,1 , ,5
Vay m = 2.0,1.120 + 0,1.160 = 40(g) Dap an dung la B. Pang 17; Bai tap .sur dung phuong phap quy đi
1. Cho 18,4 gam h6n hop X gom CU2S, CuS, FeS2 va FeS tac d u n g h6l vdi
H N O 3 (dac nong, dir) thu duoc V lit khf chi c6 N O 2 ( 0 dktc, san ph^m khir duy nhat) va dung djch Ỵ Cho toan b6 Y vao m6t luong du dung djch BaCl2, t h u duoc 46,6 gam ket tua; con khi cho toan bo Y tac dung vdi dung djch NH3 du thu duoc 10,7 gam ket tiiạ Gia tri cua V la
Ạ 11,2. > B. 38,08. C. 16,8. * D. 24,64.''
Hu&ng đn gidi
Theo bai ra: n^^^^^ = 46,6/233 = 0,2mol
"Fe(0H)3i ^•0''7/107 = 0,lmol
Quy doi h6n hop X thanh X mol Fe; y mol Cj},va z mol S
=>56x+64y + 32z = 18,4 ( l ) ' Mat khac: z = ng = nBaso4 = 0-2 (bao toan nguyen t6' luu huynh) Ta lai c6: x = np^ = np^^^^^^ =0,1 (bao toan nguydn t6'sat)
~ . 18,4-56.0,1-32.0,2 ^ , T u ( l ) = > y = ^ -i ^ = 0,1
• , +3 2+ 'Í^.fjS,
T6ng s6' mol electron do Fe -> Fe;Cu -> Cu
+6
S -> S la ne (cho) = 0,1. 3+0,1. 2+0,2. 6 = 1,7 mol
+.5 +4
=> Tong s6' mol electron do N+ le -> N la 1,7 mol
=> nN02 = l,7mol=^ VNO2 = l''7-22.4 = 38,08(£) Dap an diing la B.
^' Cho m6t luong khi CO di qua dng sir dung m gam FêOj nung nong. Sau m6t thai gian ^hu duoc 10,44 gam chat ran X g6m Fe, FeO, FêOj va F C 3 O 4 . Hoa tan
hét X trong dung dich H N O , dac, nong thu dugc 4,368 lit NO2 (san ph£m khir duy nhát of di^u kien chudn). Gia tri ciia m la
A . 12 B. 24 C. 10.8 D. 16 '
Hu&ng đn gidi . ; ; r - ii
Theobaira: nN02 = 4 , 3 6 8 / 2 2 , 4 - 0 , 1 9 5 ( m o l ) e c t O + c ^ v ;
Ta quy h6n hop X thanh 2 chat: Fe, FêOj
Fe + 6 H N O 3- > Fe(N03)3 + 3NO2 + 3H2O ' , t ' i u l % » m > x/3 - > • X
F e j O j + 6HNO3 ^ 2Fe(N03)3 + 3H2O i
i — y
Ta CO he: • '56x/3 + 160y = 10,44
X - 0,195
Giai ra ta dirge: x = 0,195; y = 0,0425
Fe203 + 3CO 2Fe + 3CO2
x/6 ^ < - x/3
Vay m - (x /6 + y ) . 160 = (0,195/6 + 0,0425). 160 = 12(g)
Dap an dung la Ạ
Dang 18: Bai tap ve cac kim loai khac
1. De lam sach thuy ngan c6 Ian tap chat Zn, Sn, Pb, c6 th^ khuáy loai thuy ngan nay vao dung djch (láy dir) nay vao dung djch (láy dir)
ẠZnCNOj),. B . A g N O j . C. H C l . D. HgCNOj)..
Hu&ng đn gidi
Nhan xet: Cac k i m loai tap cha't (Zn, Sn, Pb) d^u dutig tru6c Hg trong day dien hoa => CO thé loai cac tap chát nay bang dung dich HgCNOj),, tao ra san phdm la
Hg (khdng lam nhidm tap chat mdi vao thuy ngan) va cac mu6'i tan: Zn + HgCNOj), ^ H g i + ZnCNOj),
Sn + HgCNOj), ^ H g i + Sn(N03)2
Pb +, HgCNOj)^ > H g i + PbCNOj), Thiiy ngan sinh ra dugc tach ra khoi dung djch.
Dap an dung la I)
Chu y: Khdng dung HCl vi tao ra PbCl. khdng tan ma 15n vao Hg.
2. De thu dugc A g tinh khid't (giCr nguy6n lugng Ag) tir h6n hgp b6t A g , Cu, Fe, co
thé cho h6n hgp k i m loai nay vao dung djch (du, khuáy kl)
A . A g N 0 3 . B.H2SO4. C.Fe2(S04)3. D. CuCNO,),. IS-? IS-?
Hu&ng đn gidi
Xet cac phirong an:
loai, VI tao ra thSm Ag, do: ,1' - ,,,,
Cu + 2AgN03 > 2 A g i + CuCNO,), ' ' ' ' ' ' ' ' ^ ^
HOJL • ij,::.'
Fe + SAgNO, > 3 A g i + ¥e(NO,)^
g. loai, VI khOng loai bo dugc tap chát Cu:
Cu + H2SO4 (loang) > Khdng xay rạ,,,^ ^^.j, ;,,|';,> . C. Dugc, vi: ' •'• ' . '
Ag + Fe2(S04)3 >• khdngxayra ^Q^,-. Cu + Fe2(S04)3 > CUSO4 + 2FeS04 ^ Fe + Fe2(S04)3 > 3FeS04 " f "^^^ ' '^"^'^"'^
Con lai Ag v6\g khdng d6ị
D. loai, VI kh6ng loai dugc Cụ ' ^ Cu + Cu(N03)2 ^ khon^ xay ra