- Hoatan het phd n2 bang dung dich HNO3 dac, nong (du) tháy c6 11,76 lit khi bay ra (dktc).
17. Nung h6n hop bot gom 15,2 gam Cr^Oj vd' im gam Ala nhiet do caọ Sau kh
phan ung hoan toan, thu dugc 23,3 gam h6n hop rSn X. Cho toan b6 h6n hop X phan ung v6i axit HCl (du) thoat ra V lit khi H . (o dktc).
Gia tri cua V la
Ạ 3,36. B. 4,48. C. 7,84. D. 10,08. 106
Huong dan gidi
Theobaira: n = ^ = 0,l(mol).
L r 2 " 3 152
Trong phan ling nhiat nhom: m^, + m^^^^^ = m ^A , , ^ a u p h i , , . h - g . ' y| ;,
=^mA, = 2 3 , 3 - 1 5 , 2 = 8 , 1 (gam) ' ' nA, = 0,3 (mol).
PTPU": 2A1 + C r A . — ^ 2Cr + A l A * >' Ban dau: 0,3 0,1 (mol)
Phanu-ng: 0,2 < 0,1 > 0,2(mol) Gonial: 0,1 (mol) 0,2 (mol)
A l + 3HCI > AlCỊ, + l , 5 H , t 0,1 (mol) 0,15(mol) Cr + 2HC1 > CrCU + H,T 0,2(mol) 0,2(mol) => In H2 =0,15 + 0,2 = 0 , 3 5 (mol) = >V H^ =0,35.22,4 = 7 , 8 4 (lit) Dap an dung la C. Dang 6: Bai tap nhom tac dung vol dung djch kiem
I . Cho h6n hop g6m Na va A l c6 ti le so mol tuong irng la 1 : 2 vao nude (du). Sau khi cac phan ung xay ra hoan toan, thu dugc 8,96 lit khi (6 dktc) va m gam chat ran khong tan. Gia tri ciia m la
Ạ 5,4. B. 7,8. C. 10,8. D. 43,2.
Huong dan gidi
Goi X la s6' mol Na => s6' mol A l la 2x.
I I H 2 =8,96/22,4 = 0,4 (mol). PTPLT: Na + H.O > NaOH + l/2H,t PTPLT: Na + H.O > NaOH + l/2H,t
X X 0,5x (mol)
2AI + 2NaOH + 6 H 3 O > 2NalAI(OH)4j + SaT
Ban dau: 2x x
Phan ling: x x l,5x (mol)
Conlai: x 0 l , 5 x ( m o l ) Theo bai ra, ta c6: 0,5x + 1,5x = 0,4 => 2x = 0,4 => x = 0,2
^ay m = m^i = 0,2. 27 = 5,4 (g)
Dap an diing la Ạ
• H6n hop X gom Na va A l . Cho m gam X vao mot lugng d u nudrc thi thoat ra V lit l^hf. Néu cQng cho m gam X vao dung djch NaOH (du) thi thu dugc 1,75V lit
khf. Thanh phdn phdn tram theo khoi luong cua Na trong X la (biét cac th^ tích khi do a cung dieu kien)
Ạ 29,87%. B. 39,87%. C. 49,87%. D. 77,31%.
Hu&ng dan gidi
Goi X, y Idn luot la s6' mol Na, A l trong m gam X. ' ' ' - ' l , ' - ; ' * X + H , 0 ( d u ) :
Na + H , 0 > NaOH + - H , t 2 ^
X X 0,5x (mol)
A l + NaOH + 3 H , 0 > Na[Al(0H)4] + USH.T
'' X x 1,5x (mol)
(Dira vao thf nghiem sau, ta bie't duoc ring trong thi nghiem nay A l du, NaOH bet). * X + NaOH (dir): - : '^^' Na + HoO >NaOH + 0,5H,t X 0,5x (mol) A l + NaOH,<,„) + H , 0 > Na[Al(OH)4] + l.SH^T y 1,5 y / , _ . . . . 0,5x + l,5x V 1
Theo bai ra ta co: = = 0,5x + l,5y 1,75V 1,75 = > 0 , 5 x + l , 5 y = 3,5x=> l,5y = 3x y = 2x
% m , . = ^ . 1 0 0 % = ^ ^ . 1 0 0 % = - ^ ^ ^ ^ i ^ = 29,87%. mx 23x + 27y 23x + 27.2x
' Dap an dung Ạ