Câu 3( 4 điểm): Cho các chất: Na, NaOH, Na2O, Na2SO4 a, Hãy gọi tên và phân loại chất. b, Từ 4 chất trên hãy lập một dãy biến hóa và viết các phương trình thực hiện dãy biến hóa đó. ( Mỗi chất chỉ xuất hiện trong dãy biến hóa 1 lần, các phương trình phản ứng không trùng nhau).

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Đáp án:

`↓`

 

Giải thích các bước giải:

`a.`

`- Na:` natri (kim loại mạnh)

`- NaOH:` natri hidroxit (bazơ kiềm)

`- Na_2 O:` natri oxit (oxit bazơ tan)

`- Na_2 SO_4:` natri sunfat (muối trung hòa)

`b.`

`Na` $\xrightarrow{1}$ `Na_2 O` $\xrightarrow{2}$ `NaOH` $\xrightarrow{3}$ `Na_2 SO_4`

`1. 4Na + O_2` $\xrightarrow{t^o}$ `2Na_2 O`

`2. Na_2 O + H_2 O -> 2NaOH`

`3. 2NaOH + H_2 SO_4 -> Na_2 SO_4 + 2H_2 O`

Đáp án:

 

Giải thích các bước giải:

a.

-Na: natri (kim loại mạnh)

-NaOH: natri hidroxit (bazơ kiềm)

-Na2O: natri oxit (oxit bazơ tan)

-Na2SO4: natri sunfat (muối trung hòa)

b.

Na →1 Na2O →2 NaOH →3 Na2SO4

1.4Na+O2 →to 2Na2O

2.Na2O+H2O→2NaOH

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