, Huong din gid
2. Cho 20gam h6n hop bot g6m Fe va Cu vao dung djch axit nitric Sau khi cac
phan ling xay ra hoan toan thu dugc 4,8 gam chat rdn X, dung dich Y va 0,2 mol mot chat khi bj hoa nau trong khong khi (san pham khiJt duy nhát). Co can dung djch Y thu duoc muoi khan c6 khdi lirong la
Ạ 25,4 gam. B. 42,5 gam. C. 52,4 gam. D. 54,2 gam.
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Huong đn gidi
San phdm khir bi hod n&u trong khong khf san phdm khir la NO:
2NO + O, > 2NO2 (nau) Theo bai la: = 0,2 (mol)
+5 +2
^ + 3e — > A ' ( N O )
0,6 (mol) < 0,2 (mol) M I K V /
Theo djnh luat bao toan di6n tfch, suy ra:
(trong mu6'i nitrat sinh ra) = 0,6 (mol)
(Vi didn tfch cua ion N O ^ bang difin tfch cua electron) , ' , vay m,„„,:, = m^i^ ,p/„) + m^o " = (20 - 4,8) + 0,6.62 = 52,4 (gam)
Dap an dung la C. 3. Hoa tan 12 gam h6n hop X gom Fe va Cu (trong do Fe chiem 46,67% v l kh6'i luong)
vao dung djch axit HNO3. Sau khi cac phan ling xay ra hoan toan thu duoc 4,8 gam kim loai chira tan va dung djch Ỵ C6 can dung djch Y thu diroc m gam mudi khan. Gia trj ciia m la
Ạ 7,2 gam. B. 20 gam. C. 22,7 gam. D. 28,9 gam.
Hu&ng đn gidi
Theo bai ra, .s6' mol Fe bang: 12. 0,4667 / 56 = 0,1 (mol) mc„= 12 - 0,1.56 = 6 , 4 ( g )
Suy ra, 48 gam kim loai con lai chi c6 Cu; s6' mol kim loai Cu phan ung: iV
ncu,p/u,= (6,4 - 4,8) /64 = 0,025 mol
So d6 phan ii-ng: Fe ^ Fe(N03)2
. 0,1 (mol) 0,1 (mol)
Cu > Cu(N03),
0,025 (mol) 0,025 (mol) '(
Vay m = mp,(N03)2+mcu(N03)2 = 0.1-180+ 0,025.188 = 22,7 (gam). , .
Dap an dung la C .
. Cho h6n hop Fe, Cu phan ung v6i dung djch H N O 3 loang. Sau khi phan ihig hoan toan, thu duoc dung djch chi chiia m6t chat tan va kim loai dụ Chát tan do la
I A. H N O 3 . B.Fe(N03)2. C.Cu(N03),. D. Fe(N03)3.
Hu&ng đn gidi
|ac PTPLT (c6 théxay ra):
Fe ^ Fe(N03)3 Cu — > Cu(N03),