a. PTHH:

\(Cu+H_2SO_4--\times-->\)

\(CuO+H_2SO_4--->CuSO_4+H_2O\left(1\right)\)

\(Cu+2H_2SO_{4_{đặc}}\overset{t^o}{--->}CuSO_4+SO_2+2H_2O\left(2\right)\)

Ta có: \(n_{SO_2}=\dfrac{1,12}{22,4}=0,05\left(mol\right)\)

Theo PT₍₂₎: \(n_{Cu}=n_{SO_2}=0,05\left(mol\right)\)

\(\Rightarrow m_{Cu}=0,05.64=3,2\left(g\right)\)

\(\Rightarrow\%_{m_{Cu}}=\dfrac{3,2}{10}.100\%=32\%\)

\(\%_{m_{CuO}}=100\%-32\%=68\%\)

a)

$Cu + 2H_2SO_4 \to CuSO_4 + SO_2 + 2H_2O$
$n_{Cu} = n_{SO_2} = \dfrac{1,12}{22,4} = 0,05(mol)$
$\%m_{Cu} = \dfrac{0,05.64}{10}.100\% = 32\%$
$\%m_{CuO} = 100\% -32\% = 68\%$

b)

$NaOH + SO_2 \to NaHSO_3$
$n_{NaOH} = n_{SO_2} = 0,05(mol)$
$V_{dd\ NaOH} = \dfrac{0,05}{2} = 0,025(lít) = 25(ml)$

Ta có: \(n_{H_2}=\dfrac{2,24}{22,4}=0,1\left(mol\right)\)

PTHH:

\(Fe+H_2SO_4--->FeSO_4+H_2\uparrow\left(1\right)\)

\(Cu+H_2SO_4--\times-->\)

Theo PT₍₁₎: \(n_{Fe}=n_{H_2}=0,1\left(mol\right)\)

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

PTHH: \(Cu+2H_2SO_{4_{đặc}}\overset{t^o}{--->}CuSO_4+SO_2\uparrow+2H_2O\left(2\right)\)

Ta có: \(n_{Cu}=\dfrac{5,6}{64}=0,0875\left(mol\right)\)

Theo PT₍₂₎: \(n_{SO_2}=n_{Cu}=0,0875\left(mol\right)\)

\(\Rightarrow V_{SO_2}=0,0875.22,4=1,96\left(lít\right)\)

PT: \(CuO+H_2SO_4\rightarrow CuSO_4+H_2O\)

\(Cu+2H_2SO_{4\left(đ\right)}\underrightarrow{t^o}CuSO_4+SO_2+2H_2O\)

Ta có: \(n_{SO_2}=\dfrac{5,6}{22,4}=0,25\left(mol\right)\)

Theo PT: \(n_{Cu}=n_{SO_2}=0,25\left(mol\right)\)

\(\Rightarrow\%m_{Cu}=\dfrac{0,25.64}{24}.100\%\approx66,67\%\)

Đáp án A

C r ⇒ C r 2 + ⇒ C r ( O H ) 2 ⇒ C r ( O H ) 3 ⇒ C r 2 O 3 n C r = n H 2 = 0 , 15   ⇒ n C r 2 O 3 = 0 , 5 n C r = 0 , 5 .   0 , 15 =   0 , 75 ⇒ m C r 2 O 3 = 11 , 4 ( g )