$a\big)2Al+3H_2SO_4\to Al_2(SO_4)_3+3H_2$

$b\big)$

$n_{Al}=\dfrac{4,05}{27}=0,15(mol)$

$n_{H_2SO_4}=\dfrac{29,4}{98}=0,3(mol)$

Vì $\dfrac{n_{Al}}{2}<\frac{n_{H_2SO_4}}{3}\to H_2SO_4$ dư

$c\big)$

Theo PT: $n_{H_2}=\dfrac{3}{2}n_{Al}=0,225(mol)$

$\to V_{H_2}=0,225.22,4=5,04(l)$

a. 2Al + 3H₂SO₄ →  Al₂(SO₄)₃ + 3H₂

b. nH₂SO₄ =\(\dfrac{29,4}{98}\)=0,3 mol 

Theo phương trình ta có số mol nhôm đã phản ứng là nAl= \(\dfrac{0,3.2}{3}\)= 0,1 mol ==> a = 0,1.27 = 2,7 gam

c. Phản ứng vừa đủ nên cả Al và H₂SO₄ cùng hết , không có chất nào dư sau phản ứng

Đề bài sai vui lòng sửa lại .

2Al + 3H₂SO₄ -> Al₂(SO₄)₃ + 3H₂

nAl = 0,1 => nH₂ = 0,15 => V_H2 = 0,15 . 22,4 = 3,36 (l) 

nH₂ = 0,15 => mH₂ = 0,3(g) 

m dd sau pư = 2,7 + 200 -0,3=202,4 (g) 

theo pư => n Al₂(SO₄)₃ = 0,05 => m Al₂(SO₄)₃  = 17,1 => C% = 17,1:202,4 . 100 % = 8,45%

A)

$2Al + 3H_2SO_4 \to Al_2(SO_4)_3 + 3H_2$
B)

n Al = 2,7/27 = 0,1(mol)

Theo PTHH :

n H2 = 3/2 n Al = 0,15(mol)

=> V H2 = 0,15.22,4 = 3,36(lít)

Theo PTHH :

n Al2(SO4)3 = 1/2 n Al = 0,05(mol)

m dd sau pư = m Al + mdd H2SO4 - m H2 = 2,7 + 200 - 0,15.2 = 202,4 gam

Suy ra : 

C% Al2(SO4)3 = 0,05.342/202,4  .100% = 8,45%

\(n_{NaOH}=\dfrac{200.8\%}{100\%.40}=0,4mol\\ a)NaOH+HCl\rightarrow NaCl+H_2O\\ b)n_{NaCl}=n_{NaOH}=0,4mol\\ m_{NaCl}=0,4.58,5=23,4g\)

2Al+3H2SO4->Al2(SO4)3+3H2

0,1----------------------0,075----0,15

n H2=0,15 mol

=>mAl=0,1.27=2,7g

=>m Al2(SO4)3=0,075.342=25,65g

a) PTHH: \(2Al+3H_2SO_2\rightarrow Al_2\left(SO_4\right)_3+3H_2\)

b) \(n_{H_2}=\dfrac{3,36}{22,4}=0,15\left(mol\right)\)

\(n_{Al}=\dfrac{2}{3}.0,15=0,1\left(mol\right)\)

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

c) \(n_{Al_2\left(SO_4\right)_3}=\dfrac{1}{2}.0,1=0,05\left(mol\right)\)

\(m_{Al_2\left(SO_4\right)_3}=0,05.342=17,1\left(g\right)\)

2Al+3H2SO4->Al2(SO4)3+3H2

0,1----------------------0,075----0,15

n H2=0,15 mol

=>mAl=0,1.27=2,7g

=>m Al2(SO4)3=0,075.342=25,65g

Câu 2 : 

\(Na+H_2O\rightarrow NaOH+\dfrac{1}{2}H_2\)

\(CuO+H_2\underrightarrow{^{t^0}}Cu+H_2O\)

\(K+H_2O\rightarrow KOH+\dfrac{1}{2}H_2\)

\(4P+5O_2\underrightarrow{^{ }t^0}2P_2O_5\)

\(3Fe+2O_2\underrightarrow{^{t^0}}Fe_3O_4\)

\(Zn+2HCl\rightarrow ZnCl_2+H_2\)

\(Fe+H_2SO_4\rightarrow FeSO_4+H_2\)

\(Zn+H_2SO_4\rightarrow ZnSO_4+H_2\)

Câu 3 : 

\(n_{H_2}=\dfrac{2.7}{27}=0.1\left(mol\right)\)

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

\(0.1...........................0.05.......0.15\)

\(V_{H_2}=0.15\cdot22.4=3.36\left(l\right)\)

\(m_{Al_2\left(SO_4\right)_3}=0.05\cdot342=17.1\left(g\right)\)

\(m_{\text{dung dịch sau phản ứng}}=2.7+200-0.15\cdot2=202.4\left(g\right)\)

\(C\%_{Al_2\left(SO_4\right)_3}=\dfrac{17.1}{202.4}\cdot100\%=8.44\%\)

\(n_{Al}=\dfrac{5,4}{27}=0,2\left(mol\right)\\a, 2Al+3H_2SO_4\rightarrow Al_2\left(SO_4\right)_3+3H_2\\ n_{H_2}=n_{H_2SO_4}=\dfrac{3}{2}.0,2=0,3\left(mol\right)\\ b,V_{H_2\left(đktc\right)}=0,3.22,4=6,72\left(l\right)\\ c,n_{Al_2\left(SO_4\right)_3}=\dfrac{1}{2}.0,2=0,1\left(mol\right)\\ m_{Al_2\left(SO_4\right)_3}=0,1.342=34,2\left(g\right)\\ d,C\%_{ddH_2SO_4}=\dfrac{0,3.98}{200}.100\%=14,7\%\\ e,m_{ddmuoi}=5,4+200-0,3.2=204,8\left(g\right)\\ C\%_{ddAl_2\left(SO_4\right)_3}=\dfrac{34,2}{204,8}.100\%\approx16,699\%\)

\(a)2Al+3H_2SO_4\rightarrow Al_2\left(SO_4\right)_3+3H_2\\ b)n_{Al}=\dfrac{5,4}{27}=0,2mol\\ 2Al+3H_2SO_4\rightarrow Al_2\left(SO_4\right)_3+3H_2\)

\(0,2-\rightarrow0,3--\rightarrow0,1--\rightarrow0,3\)

\(m_{H_2}=0,3.2=0,6g\\ c)m_{Al_2\left(SO_4\right)_3}=0,1.342=34,2g\\ d)C_{\%H_2SO_4}=\dfrac{0,3.98}{200}\cdot100=14,7\%\\ e)C_{\%Al_2\left(SO_4\right)_3}=\dfrac{34,2}{5,4+200-0,6}\cdot100=16,7\%\)

Sửa: \(14,7\%\)

\(n_{H_2SO_4}=\dfrac{200.14,7\%}{100\%.98}=0,3(mol)\\ a,PTHH:2Al+3H_2SO_4\to Al_2(SO_4)_3+3H_2\\ \Rightarrow n_{H_2}=0,3(mol)\\ \Rightarrow V_{H_2}=0,3.22,4=6,72(l)\\ b,n_{Al}=\dfrac{2}{3}n_{H_2SO_4}=0,2(mol)\\ \Rightarrow m_{Al}=0,2.27=5,4(g)\\ c,n_{Al_2(SO_4)_3}=\dfrac{1}{2}n_{Al}=0,1(mol)\\ \Rightarrow C\%_{Al_2(SO_4)_3}=\dfrac{0,1.342}{200+5,4-0,3.2}.100\%=16,7\%\\ c,m_{Al_2(SO_4)_3}=0,1.342=34,2(g)\)