Giải bài 5 trang 79 SGK Hóa học 10 Kết nối tri thức - KNTT

Hướng dẫn giải

Dấu hiệu để nhận biết phản ứng oxi hóa – khử là có sự thay đổi số oxi hóa của các nguyên tử.

Lời giải chi tiết

Các phản ứng oxi hóa – khử là: a; b; c và d.

a)

* Fe₂O₃  +  CO \(\xrightarrow{{{t^o}}}\)    FeO + CO₂

Bước 1:

\({\mathop {Fe}\limits^{ + 3} _2}{O_3} + \mathop C\limits^{ + 2} O \to \mathop {Fe}\limits^{ + 2} O + \mathop C\limits^{ + 4} {O_2}\)

Bước 2:

\(\begin{array}{l}
\mathop {Fe}\limits^{ + 3} \,\,\, + \,\,1e\,\,\,\, \to \,\,\,\,\mathop {Fe}\limits^{ + 2} \,\,\\
C\,\,\, \to \,\,\,\mathop C\limits^{ + 2} \,\, + \,\,\,\,2e
\end{array}\)

Bước 3:

\(\begin{array}{l}
2\,\,x\,\,\,\,\,\,\,\mathop {Fe}\limits^{ + 3} \,\,\, + \,\,1e\,\,\,\, \to \,\,\,\,\mathop {Fe}\limits^{ + 2} \,\,\\
1\,\,\,x\,\,\,\,\,\,\,\,C\,\,\, \to \,\,\,\mathop C\limits^{ + 2} \,\, + \,\,\,\,2e
\end{array}\)

Bước 4:

Fe₂O₃  +  3CO \(\xrightarrow{{{t^o}}}\)  2FeO + 3CO₂  

* FeO + CO \(\xrightarrow{{{t^o}}}\) Fe + CO₂

Bước 1:

Bước 2:

\(\begin{array}{l}
\mathop {Fe}\limits^{ + 2} \,\,\, + \,\,2e\,\,\,\, \to \,\,\,\,\mathop {Fe}\limits^0 \,\,\\
\,\mathop C\limits^{ + 2} \,\,\,\, \to \,\,\mathop C\limits^{ + 4} \,\,\,\, + \,\,\,\,2e
\end{array}\)

Bước 3:

\(\begin{array}{l}
1\,\,x\,\,\,\,\,\mathop {Fe}\limits^{ + 2} \,\,\, + \,\,2e\,\,\,\, \to \,\,\,\,\mathop {Fe}\limits^0 \,\,\\
1\,\,x\,\,\,\,\,\mathop C\limits^{ + 2} \,\,\,\, \to \,\,\mathop C\limits^{ + 4} \,\,\,\, + \,\,\,\,2e
\end{array}\)

Bước 4:

FeO + CO \(\xrightarrow{{{t^o}}}\) Fe + CO₂

b)

* ZnS + O₂   \(\xrightarrow{{{t^o}}}\)  ZnO + SO₂           

Bước 1:

\(Zn\mathop S\limits^{ - 2} \,\, + \,\,\,\mathop {{O_2}}\limits^0 \,\,\, \to \,\,\,Zn\mathop O\limits^{ - 2} \,\,\,\, + \,\,\,\mathop S\limits^{ + 4} \,{O_2}\)

Bước 2:

\(\mathop S\limits^{ - 2} \,\,\,\, \to \,\,\,\,\,\mathop S\limits^{ + 4} \,\,\,\, + \,\,\,6e\)

\(\mathop {{O_2}}\limits^0 \,\,\,\, + \,\,\,4e\,\,\,\, \to \,\,\,\,2\mathop O\limits^{ - 2} \)

Bước 3:

\(\begin{array}{l}
2\,\,x\,\,\,\,\mathop S\limits^{ - 2} \,\,\,\, \to \,\,\,\,\,\mathop S\limits^{ + 4} \,\,\,\, + \,\,\,6e\\
3\,\,\,x\,\,\,\mathop {{O_2}}\limits^0 \,\,\,\, + \,\,\,4e\,\,\,\, \to \,\,\,\,2\mathop O\limits^{ - 2} 
\end{array}\)

Bước 4:

 2ZnS + 3O₂   \(\xrightarrow{{{t^o}}}\)  2ZnO + 2SO₂      

* ZnO + C \(\xrightarrow{{{t^o}}}\)  Zn + CO

Bước 1:

\(\mathop {Zn}\limits^{ + 2} O\,\,\, + \,\,\,\,\mathop C\limits^0 \,\,\,\, \to \,\,\,\,\mathop {Zn}\limits^0 \,\,\,\,\, + \,\,\,\,\mathop C\limits^{ + 2} O\)

Bước 2:

\(\begin{array}{l}
\mathop {Zn}\limits^{ + 2} \,\,\,\,\, + \,\,\,2e\,\,\,\, \to \,\,\,\,\mathop {Zn}\limits^0 \\
\,\mathop C\limits^0 \,\,\, \to \,\,\,\,\mathop C\limits^{ + 2} \,\,\,\, + \,\,\,\,2e
\end{array}\)

Bước 3:

\(\begin{array}{l}
1\,\,x\,\,\,\mathop {Zn}\limits^{ + 2} \,\,\,\,\, + \,\,\,2e\,\,\,\, \to \,\,\,\,\mathop {Zn}\limits^0 \\
1\,\,x\,\,\,\,\mathop C\limits^0 \,\,\, \to \,\,\,\,\mathop C\limits^{ + 2} \,\,\,\, + \,\,\,\,2e
\end{array}\)

Bước 4:

ZnO + C  \(\xrightarrow{{{t^o}}}\) Zn + CO

c)

\(NaCl\,\,\, + \,\,\,{H_2}O\,\,\, \to \,\,\,\,NaOH\,\,\, + \,\,C{l_2}\,\,\, + \,\,\,{H_2}\)             

Bước 1:

\(Na\mathop {Cl}\limits^{ - 1} \,\,\, + \,\,\,{\mathop H\limits^{ + 1} _2}O\,\,\, \to \,\,\,\,NaOH\,\,\, + \,\,{\mathop {Cl}\limits^0 _2}\,\,\, + \,\,\,{\mathop H\limits^0 _2}\)

Bước 2:

\(\begin{array}{l}
2\mathop {Cl}\limits^{ - 1} \,\,\,\, \to \,\,\,\,{\mathop {Cl}\limits^0 _2}\, + \,\,\,\,2e\\
2\mathop H\limits^{ + 1} \,\,\, + \,\,2e\,\,\,\, \to \,\,\,{\mathop H\limits^0 _2}
\end{array}\) 

Bước 3:

\(\begin{array}{l}
1\,\,x\,\,\,\,2\mathop {Cl}\limits^{ - 1} \,\,\,\, \to \,\,\,\,{\mathop {Cl}\limits^0 _2}\, + \,\,\,\,2e\\
1\,\,\,x\,\,\,\,2\mathop H\limits^{ + 1} \,\,\, + \,\,2e\,\,\,\, \to \,\,\,{\mathop H\limits^0 _2}
\end{array}\)

Bước 4:

\(2NaCl{\mkern 1mu} {\mkern 1mu} {\mkern 1mu}  + {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} 2{H_2}O{\mkern 1mu} {\mkern 1mu} {\mkern 1mu}  \to {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} 2NaOH{\mkern 1mu} {\mkern 1mu} {\mkern 1mu}  + {\mkern 1mu} {\mkern 1mu} C{l_2}{\mkern 1mu} {\mkern 1mu} {\mkern 1mu}  + {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {H_2}\)             

d) C₂H₅OH + O₂  \(\xrightarrow{{{t^o}}}\)  CO₂ + H₂O

Bước 1:

\({\mathop C\limits^{ - 2} _2}{H_5}OH + \mathop {{O_2}}\limits^0  \to \mathop C\limits^{ + 4} {O_2} + {H_2}\mathop O\limits^{ - 2} \)

Bước 2:

\(\begin{array}{l}
\mathop C\limits^{ - 2} \,\,\, \to \mathop C\limits^{ + 4} \,\,\,\, + \,\,\,6e\\
\mathop {{O_2}}\limits^0 \,\,\,\, + \,\,\,4e\,\, \to \,\,2\mathop O\limits^{ - 2} 
\end{array}\)

Bước 3:

\(\begin{array}{l}
2\,\,\,x\,\,\,\,\mathop C\limits^{ - 2} \,\,\, \to \mathop C\limits^{ + 4} \,\,\,\, + \,\,\,6e\\
3\;\,\,x\,\,\,\mathop {{O_2}}\limits^0 \,\,\,\, + \,\,\,4e\,\, \to \,\,2\mathop O\limits^{ - 2} 
\end{array}\)

Bước 4:

C₂H₅OH + 9/2O₂ \(\xrightarrow{{{t^o}}}\) 2CO₂ + 6H₂O

-- Mod Hóa Học 10 HỌC247