\(a,n_{Fe}=\dfrac{11,2}{56}=0,2\left(mol\right)\\ PTHH:Fe+2HCl\rightarrow FeCl_2+H_2\\ \Rightarrow n_{HCl}=0,4\left(mol\right)\\ \Rightarrow m_{CT_{HCl}}=0,4\cdot36,5=14,6\left(g\right)\\ \Rightarrow C\%_{HCl}=\dfrac{14,6}{200}\cdot100\%=7,3\%\\ b,n_{H_2}=0,2\left(mol\right)\\ \Rightarrow V_{H_2\left(đkc\right)}=0,2\cdot24,79=4,958\left(l\right)\\ c,m_{H_2}=0,2\cdot2=0,4\left(g\right)\\ n_{FeCl_2}=0,2\left(mol\right)\\ \Rightarrow m_{CT_{FeCl_2}}=0,2\cdot127=25,4\left(g\right)\\ \Rightarrow m_{dd_{FeCl_2}}=11,2+200-0,4=210,8\left(g\right)\\ \Rightarrow C\%_{FeCl_2}=\dfrac{25,4}{210,8}\cdot100\%\approx12,05\%\)

Bài 1: 

PTHH: \(Mg+2HCl\rightarrow MgCl_2+H_2\uparrow\)

Ta có: \(n_{Mg}=\dfrac{4,8}{24}=0,2\left(mol\right)\)

\(\Rightarrow\left\{{}\begin{matrix}n_{HCl}=0,4\left(mol\right)\\n_{H_2}=0,2\left(mol\right)\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}m_{ddHCl}=\dfrac{0,4\cdot36,5}{14,6\%}=100\left(g\right)\\V_{H_2}=0,2\cdot22,4=4,48\left(l\right)\end{matrix}\right.\)

Bài 2:

PTHH: \(2KOH+H_2SO_4\rightarrow K_2SO_4+2H_2O\)

Ta có: \(\left\{{}\begin{matrix}n_{KOH}=\dfrac{100\cdot11,2\%}{56}=0,2\left(mol\right)\\n_{H_2SO_4}=\dfrac{150\cdot9,8\%}{98}=0,15\left(mol\right)\end{matrix}\right.\)

Xét tỉ lệ: \(\dfrac{0,2}{2}< \dfrac{0,15}{1}\) \(\Rightarrow\) H₂SO₄ còn dư, KOH p/ứ hết

\(\Rightarrow\left\{{}\begin{matrix}n_{K_2SO_4}=0,1\left(mol\right)\\n_{H_2SO_4\left(dư\right)}=0,05\left(mol\right)\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}m_{K_2SO_4}=0,1\cdot174=17,4\left(g\right)\\m_{H_2SO_4\left(dư\right)}=0,05\cdot98=4,9\left(g\right)\end{matrix}\right.\)

Mặt khác: \(m_{dd}=m_{ddKOH}+m_{ddH_2SO_4}=250\left(g\right)\)

\(\Rightarrow\left\{{}\begin{matrix}C\%_{K_2SO_4}=\dfrac{17,4}{250}\cdot100\%=6,96\%\\C\%_{H_2SO_4\left(dư\right)}=\dfrac{4,9}{250}\cdot100\%=1,96\%\end{matrix}\right.\)

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

a) \(n_{Al}=\dfrac{10,8}{27}=0,4\left(mol\right)\)

Theo pt: \(n_{H_2}=\dfrac{3}{2}n_{Al}=\dfrac{3}{2}.0,4=0,6\left(mol\right)\)

\(V_{H_2}=0,6.22,4=13,44\left(l\right)\)

b) Theo pt: \(n_{H_2SO_4}=\dfrac{3}{2}n_{Al}=\dfrac{3}{2}.0,4=0,6\left(mol\right)\)

\(m_{H_2SO_4}=0,6.98=58,8g\)

\(C_{\%}dd_{H_2SO_4}=\dfrac{m_{ct}}{m_{dd}}.100\%=\dfrac{58,8}{200}.100\%=29,4\%\)

c) Theo pt: \(n_{Al_2\left(SO_4\right)_3}=\dfrac{n_{Al}}{2}=0,2\left(mol\right)\)

\(m_{Al_2\left(SO_4\right)_3}=0,2.342=68,4\left(g\right)\)

Áp dụng định luật bảo toàn khối lượng

\(m_{dd_{Al_2\left(SO_4\right) _3}}=m_{Al}+m_{dd_{H_2SO_4}}-m_{H_2}\)

\(=10,8+200-0,6.2=209,6g\)

\(C_{\%_{Al_2\left(SO_4\right)_3}}=\dfrac{68,4}{209,6}.100\%\approx32,6\%\)

a) \(2KOH+H_2SO_4\rightarrow K_2SO_4+2H_2O\)

\(n_{KOH}=\dfrac{200.11,2\%}{56}=0,4\left(mol\right)\)

\(n_{H_2SO_4}=\dfrac{1}{2}n_{KOH}=0,2\left(mol\right)\)

\(m_{ddH_2SO_4}=\dfrac{0,2.98}{10\%}=196\left(g\right)\)

b) \(n_{K_2SO_4}=\dfrac{1}{2}n_{KOH}=0,2\left(mol\right)\)

\(m_{ddsaupu}=200+196=396\left(g\right)\)

=> \(C\%_{K2SO4}=\dfrac{0,2.174}{396}.100=8,79\%\)

c) \(3KOH+FeCl_3\rightarrow Fe\left(OH\right)_3+3KCl\)

\(n_{FeCl_3}=n_{Fe\left(OH\right)_3}=\dfrac{1}{3}n_{KOH}=\dfrac{2}{15}\left(mol\right)\)

=>\(V_{FeCl_3}=\dfrac{2}{15}=0,13\left(l\right)\)

\(m_{Fe\left(OH\right)_3}=\dfrac{2}{15}.107=14,27\left(g\right)\)

KOH 11,2% hay 11,2 gam em?

\(n_{Al}=\dfrac{21,6}{27}=0,8\left(mol\right)\)

Pt : \(2Al+3H_2SO_4\rightarrow Al_2\left(SO_4\right)_3+3H_2O|\)

        2             3                  1                3

       0,8          1,2               0,4             1,2

a) \(n_{H2}=\dfrac{0,8.3}{2}=1,2\left(mol\right)\)

\(V_{H2\left(dktc\right)}=1,2.22,4=26,88\left(l\right)\)

b) \(n_{H2SO4}=\dfrac{0,8.3}{2}=1,2\left(mol\right)\)

⇒ \(m_{H2SO4}=1,2.98=117,6\left(g\right)\)

\(m_{ddH2SO4}=\dfrac{117,6.100}{29,4}=400\left(g\right)\)

c) \(n_{Al2\left(SO4\right)3}=\dfrac{1,2.1}{3}=0,4\left(mol\right)\)

⇒ \(m_{Al2\left(SO4\right)3}=0,4.342=136,8\left(g\right)\)

\(m_{ddspu}=21,6+400-\left(1,2.2\right)=419,2\left(g\right)\)

\(C_{Al2\left(SO4\right)3}=\dfrac{136,8.100}{419,2}=32,63\)⁰/₀

 Chúc bạn học tốt

\(n_{Fe}=\dfrac{11.2}{56}=0.2\left(mol\right)\)

\(Fe+2HCl\rightarrow FeCl_2+H_2\)

\(0.2...................0.2..........0.2\)

\(V_{H_2}=0.2\cdot22.4=4.48\left(l\right)\)

\(m_{FeCl_2}=0.2\cdot127=25.4\left(g\right)\)

\(m_{\text{dung dịch sau phản ứng}}=11.2+200-0.2\cdot2=210.8\left(g\right)\)

\(C\%_{FeCl_2}=\dfrac{25.4}{210.8}\cdot100\%=12.05\%\)

Giúp với mai mình thi rồi!