\(m_{MgSO_4}=\dfrac{75\cdot40}{100}=30g\) \(\Rightarrow n_{MgSO_4}=0,25mol\)

\(MgSO_4+2KOH\rightarrow Mg\left(OH\right)_2\downarrow+K_2SO_4\)

 0,25          0,5

\(m_{KOH}=0,5\cdot56=28g\) 

\(m_{ddKOH}=\dfrac{28}{11,2\%}\cdot100\%=250g\)

a)

\(2Cu + O_2 \xrightarrow{t^o} 2CuO\)

b)

\(n_{CuO} = n_{Cu} = \dfrac{6,4}{64} = 0,1(mol)\\ \Rightarrow m_{CuO} = 0,1.80 = 8(gam)\)

c)

\(n_{O_2} = \dfrac{1}{2}n_{Cu} = 0,05(mol)\\ 2KMnO_4 \xrightarrow{t^o} K_2MnO_4 + MnO_2 + O_2\\ m_{KMnO_4} = 2n_{O_2} = 0,05.2 = 0,1.158 = 15,8(gam)\)

d)

\(V_{không\ khí} = 5V_{O_2} = 0,05.22,4.5 = 5,6(lít)\)

a+b) PTHH: \(2Fe+3Cl_2\xrightarrow[]{t^o}2FeCl_3\)

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

Ta có: \(n_{Fe}=\dfrac{11,2}{56}=0,2\left(mol\right)\) \(\Rightarrow\left\{{}\begin{matrix}n_{Cl_2}=0,3\left(mol\right)\\n_{HCl}=0,4\left(mol\right)\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}m_{Cl_2}=0,3\cdot71=21,3\left(g\right)\\V_{HCl}=\dfrac{0,4}{2}=0,2\left(l\right)=200\left(ml\right)\end{matrix}\right.\) 

\(n_P=\dfrac{12}{31}mol\)

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

\(\dfrac{12}{21}\)\(\rightarrow\)\(\dfrac{5}{7}\)

Khối lượng \(KMnO_4\) cần dùng để thu lượng khí trên:

\(2KMnO_4\underrightarrow{t^o}K_2MnO_2+MnO_2+O_2\)

\(\dfrac{10}{7}\)          \(\leftarrow\)                                    \(\dfrac{5}{7}\)

\(\Rightarrow m_{KMnO_4}=\dfrac{10}{7}\cdot158=225,71g\)

Nếu không dùng \(KMnO_4\) mà dùng \(KClO_3\) để thu được khí đủ dùng trên:

\(2KClO_3\underrightarrow{t^o}2KCl+3O_2\)

\(\dfrac{10}{21}\)        \(\leftarrow\)               \(\dfrac{5}{7}\)

\(m_{KClO_3}=\dfrac{10}{21}\cdot122,5=58,33g\)

nP = 12/31 (mol)

PTHH: 4P + 5O2 -> (to) 2P2O5

Mol: 12/31 ---> 15/31

2KMnO4 -> (to) K2MnO4 + MnO2 + O2

nKMnO4 = 15/31 . 2 = 30/31 (mol)

mKMnO4 = 30/31 . 158 = 4740/31 (g)

PTHH: 2KClO3 -> (to, MnO2) 2KCl + 3O2

nKClO3 = 30/31 : 3 . 2 = 15/31 (mol)

mKClO3 = 15/31 . 122,5 = 3675/62 (g)

a, \(Fe_3O_4+4H_2\underrightarrow{t^o}3Fe+4H_2O\)

b, \(n_{Fe}=\dfrac{11,2}{56}=0,2\left(mol\right)\)

Theo PT: \(n_{Fe_3O_4}=\dfrac{1}{3}n_{Fe}=\dfrac{1}{15}\left(mol\right)\Rightarrow m_{Fe_3O_4}=\dfrac{1}{15}.232=\dfrac{232}{15}\left(g\right)\)

c, \(n_{H_2}=\dfrac{4}{3}n_{Fe}=\dfrac{4}{15}\left(mol\right)\Rightarrow V_{H_2}=\dfrac{4}{15}.22,4=\dfrac{448}{75}\left(l\right)\)

d, \(Zn+2HCl\rightarrow ZnCl_2+H_2\)

\(n_{Zn}=n_{H_2}=\dfrac{4}{15}\left(mol\right)\Rightarrow m_{Zn}=\dfrac{4}{15}.65=\dfrac{52}{3}\left(g\right)\)

\(n_{HCl}=2n_{H_2}=\dfrac{8}{15}\left(mol\right)\Rightarrow m_{HCl}=\dfrac{8}{15}.36,5=\dfrac{292}{15}\left(g\right)\)

\(n_{Fe}=\dfrac{11,2}{56}=0,2\left(mol\right)\) ; \(n_{O_2}=\dfrac{5,6}{22,4}=0,25\left(mol\right)\)

\(3Fe+2O_2\rightarrow\left(t^o\right)Fe_3O_4\)

0,2  <  0,25                        ( mol )

0,2      \(\dfrac{2}{15}\)                 \(\dfrac{1}{15}\)   ( mol )

`->` Chất dư là O₂

\(m_{O_2\left(dư\right)}=\left(0,25-\dfrac{2}{15}\right).32=3,73\left(g\right)\)

\(V_{kk}=V_{O_2}.5=\dfrac{2}{15}.22,4.5=14,93\left(l\right)\)

\(m_{bôt.sắt}=\dfrac{11,2.100}{100-12}=12,72\left(g\right)\)

\( CuO+H_2\rightarrow\left(t^o\right)Cu+H_2O\\ n_{H_2}=\dfrac{11,2}{22,4}=0,5\left(mol\right)\\ n_{CuO}=\dfrac{48}{80}=0,6\left(mol\right)\\ Vì:\dfrac{0,5}{1}< \dfrac{0,6}{1}\Rightarrow CuO\left(dư\right)\Rightarrow Tính.theo.n_{H_2}\\ Đặt:a=n_{CuO\left(p.ứ\right)}\\ m_{rắn}=41,6\left(g\right)\\ \Leftrightarrow64a+80.\left(0,6-a\right)=41,6\\ \Leftrightarrow a=0,4\left(mol\right)\\ n_{CuO\left(LT\right)}=n_{H_2}=0,5\left(mol\right)\\ \Rightarrow H=\dfrac{n_{CuO\left(TT\right)}}{n_{CuO\left(LT\right)}}.100\%=\dfrac{0,4}{0,5}.100=80\%\)

Thể tích H₂ phản ứng: 11,2 (lít) (đề bài)

\( \%m_{CuO\left(p.ứ\right)}=\dfrac{0,4}{0,6}.100\%=66,667\%\) (Do số mol tỉ lệ thuận với khối lượng)