a)

n KMnO4 = 0,26(mol)

Bảo toàn electron : 

5n KMnO4 = 2n SO2

<=> n SO2 = 0,26.5/2 = 0,65(mol)

V SO2 = 0,65.22,4 = 14,56 lít

b)

n H2SO4 pư = 2n SO2 = 0,65.2 = 1,3(mol)

n H2SO4 dư = 1,3.10% = 0,13(mol)

=> n H2SO4 đã dùng = 1,3 + 0,13 = 1,43(mol)

C% H2SO4 = 1,43.98/150   .100% = 93,43%

Gọi \(\left\{{}\begin{matrix}n_{Cu}=a\left(mol\right)\\n_{Fe}=b\left(mol\right)\end{matrix}\right.\left(đk:a,b>0\right)\)

PTHH:

\(Cu+2H_2SO_{4\left(đặc,nóng\right)}\rightarrow CuSO_4+SO_2\uparrow+2H_2O\)

a------------------------------->a

\(2Fe+6H_2SO_{4\left(đặc,nóng\right)}\rightarrow Fe_2\left(SO_4\right)_3+3SO_2\uparrow+6H_2O\)

b----------------------------------->0,5b

\(2NaOH+CuSO_4\rightarrow Cu\left(OH\right)_2\downarrow+Na_2SO_4\)

                     a---------->a

\(6NaOH+Fe_2\left(SO_4\right)_3\rightarrow2Fe\left(OH\right)_3\downarrow+3Na_2SO_4\)

                    0,5b----------->a

Theo bài ra, ta có hệ: \(\left\{{}\begin{matrix}160a+400.0,5b=71,2\\98a+107b=40,2\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}a=0,17\left(mol\right)\\b=0,22\left(mol\right)\end{matrix}\right.\left(TM\right)\)

\(\rightarrow m=0,17.64+0,22.56=23,2\left(g\right)\)

Đáp án B

+ Sơ đồ phản ứng:

+     T r o n g     Y     c ó :     n F e 2 ( S O 4 ) 3 = 0 , 5 x n M g S O 4 = y n H 2 S O 4 = z ⇒ n F e = n F e ( O H ) 3 = x n M g = n M g ( O H ) 2 = y n B a S O 4 = ( 1 , 5 x + y + z ) ⇒ 56 x + 24 y = 31 1 , 5 x + y + z = 1 , 2375 107 x + 58 y + 1 , 2375 . 233 = 359 , 7125 ⇒ x = 0 , 125 y = 1 z = 0 , 05 +     B T E     c h o     ( 1 ) :     0 , 125 . 3 + 1 . 2 = 0 , 0525 . 6 + 8 n H 2 S + 2 n S O 2 m ( H 2 S ,     S O 2 ) = 34 n H 2 S + 64 n S O 2 = 32 , 287 ⇒ x = 0 , 1515 y = 0 , 424 ⇒ d = 32 , 287 2 ( 0 , 1515 + 0 , 424 ) = 28 , 05

Đáp án B

Đáp án B

m_X = 56a+64b+16(1,5a+b-0,135) = 38,64

=> 80a + 80b = 40,8 (1)

m_{muối sunfat} = 200a + 160b = 99,6

=> a = 0,45; b=0,06

m ↓ = 0,225.32 + 0,06.96 = 12,96 (g)