Đáp án A

\(Fe+H_2SO_4\rightarrow FeSO_4+H_2\left(1\right)\)

x        x                    

\(2Al+3H_2SO_4\rightarrow Al_2\left(SO_4\right)_3+3H_2\left(2\right)\)

y          1,5y            

Đổi: 400ml = 0,4l

\(n_{H_2SO_4}=C_M.V=1.0,4=0,4\left(mol\right)\)

Gọi x,y lần lượt là số mol của Fe, Al

Từ(1),(2) =>\(\left\{{}\begin{matrix}x+1,5y=0,4\\56x+27y=11\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=0,1\\y=0,2\end{matrix}\right.\)

\(m_{Al}=0,2.27=5,4\left(g\right)\)

\(m_{Fe}=0,1.56=5,6\left(g\right)\)

\(C_{M_{FeSO_4}}=\dfrac{0,1}{0,4}=0,25M\)

\(C_{M_{Al_2\left(so_4\right)_3}}=\dfrac{0,1}{0,4}=0,25M\)

1. \(CaCl_2+2AgNO_3\rightarrow Ca\left(NO_3\right)_2+2AgCl_{\downarrow}\)

\(n_{AgCl}=\dfrac{28,7}{143,5}=0,2\left(mol\right)\)

Theo PT: \(n_{Ca\left(NO_3\right)_2}=\dfrac{1}{2}n_{AgCl}=0,1\left(mol\right)\)

\(\Rightarrow C_{M_{Ca\left(NO_3\right)_2}}=\dfrac{0,1}{0,15+0,05}=0,5\left(M\right)\)

2. \(n_{Na}=\dfrac{2,3}{23}=0,1\left(mol\right)\)

BTNT Na, có: n_NaOH = n_Na = 0,1 (mol)

\(n_{Al}=\dfrac{5,4}{27}=0,2\left(mol\right)\)

\(2Al+2NaOH+2H_2O\rightarrow2NaAlO_2+3H_2\)

Xét tỉ lệ \(\dfrac{0,2}{2}>\dfrac{0,1}{2}\), ta được Al dư.

Theo PT: \(n_{H_2}=\dfrac{3}{2}n_{NaOH}=0,15\left(mol\right)\Rightarrow V_{H_2}=0,15.22,4=3,36\left(l\right)\)

\(n_{Al\left(pư\right)}=n_{NaOH}=0,1\left(mol\right)\Rightarrow n_{Al\left(dư\right)}=0,2-0,1=0,1\left(mol\right)\)

\(\Rightarrow m_{Al\left(dư\right)}=0,1.27=2,7\left(g\right)\)

a) \(n_{Fe}=\dfrac{2,8}{56}=0,05\left(mol\right)\)

PTHH: `Fe + 2HCl -> FeCl_2 + H_2`

           0,05->0,1----->0,05---->0,05

`=> V_{ddHCl} = (0,1)/2 = 0,05 (l)`

b) `V_{H_2} = 0,05.22,4 = 1,12 (l)`

c) `C_{M(FeCl_2)} = (0,05)/(0,05) = 1M`

Đáp án A

+   S ơ   đ ồ   p h ả n   ứ n g :         C l 2 O 2 ⏟ 8 , 654     ( g ) +     M g ,     A l           Z n ⏟ 0 , 396     m o l → t 0 o x i t m u ố i ⏟ 23 , 246     ( g ) → V   m l H C l   1 M M g 2 + ,     A l 3 + Z n 2 + ,     C l - ⏟ T → 0 , 572   m o l B a ( O H ) 2 M g ( O H ) 2 ↓ +     P h ả n   ứ n g   c ủ a   T   v ớ i     B a ( O H ) 2 :                   M g + 2 O H - → M g ( O H ) 2                   Z n 2 + + 4 O H - → Z n O 2 2 - + 2 H 2 O                 A l 3 + + 4 O H - → A l O 2 - + 2 H 2 O +     n M g = x n Z n = y n A l = z ⇒ n Y = x + y + z = 0 , 396 m Y = 24 x + 65 y + 27 z = 23 , 246 - 8 , 654 2 x + 4 y + 4 z = n O H - = 1 , 144 ⇒ x = 0 , 22 y = 0 , 12 z = 0 , 056 +     m X = 71 n C l 2 + 32 n O 2 = 8 , 654 B T E :     2 n C l 2 + 4 n O 2 = 0 , 22 . 2 + 0 , 12 . 2 + 0 , 056 . 3 ⇒ n C l 2 = 0 , 034 n O 2 = 0 , 195 +     n H + = 2 n O 2 - = 2 . 2 n O 2 = 0 , 78     m o l ⇒ V H C l     1 M = 0 , 78     l í t = 780     m l

Đáp án A