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<blockquote data-quote="vanhieu1995" data-source="post: 117364" data-attributes="member: 109931">Tuyển tập tất cả các phương pháp cân bằng phản ứng oxi hóa khử -có so sánh các phương pháp.
[f=800]https://server1.vnkienthuc.com/files/815/04-phuongphapcanbangpuoxihoakhu.pdf[/f]Nguyên tắc chung để cân bằng phản ứng oxi hóa khử là số điện tử cho của chất khử phải bằng sốđiện tử nhận của chất oxi hóa hay số oxi hóa tăng của chất khử phải bằng số oxi hóa giảm của chất oxi hóa. III.1.&nbsp; PHƯƠNG PHÁP CÂN BẰNG ĐIỆN TỬ (THĂNG BẰNG ELECTRON) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Thực hiện các giai đoạn: &nbsp;&nbsp; &nbsp; + Viết phương trình phản ứng xảy ra với đầy đủ tác chất, sản phẩm (nếu đầu bài yêu cầu bổsung phản ứng, rồi mới cân bằng). &nbsp;&nbsp; &nbsp; + Tính số oxi hóa của nguyên tố có số oxi hóa thay đổi. Nhận diện chất oxi hóa, chất khử. &nbsp; &nbsp; + Viết phản ứng cho, phản ứng nhận điện tử (Phản ứng oxi hóa, phản ứng khử). Chỉ cần viết nguyên tử của nguyên tố có số oxi hóa thay đổi, với số oxi hóa được để bên trên. Thêm hệ sốthích hợp để số nguyên tử của nguyên tố có số oxi hóa thay đổi hai bên bằng nhau. &nbsp;&nbsp; &nbsp; + Cân bằng số điện tử cho, nhận. Số điện tử cho của chất khử bằng số điện tử nhận của chất oxi hóa (Hay số oxi hóa tăng của chất khử bằng số oxi hóa giảm của chất oxi hóa) bằng cách thêm hệsố thích hợp. &nbsp;&nbsp; &nbsp; + Phối hợp các phản ứng cho, nhận điện tử; các hệ số cân bằng tìm được; và phản ứng lúc đầu để bổ sung hệ số thích hợp vào phản ứng lúc đầu.&nbsp;&nbsp; &nbsp; + Cuối cùng cân bằng các nguyên tố còn lại (nếu có) như phản ứng trao đổi. Các thí dụ: Cân bằng các phản ứng sau đây theo phương pháp cân bằng điện tử. Thí dụ 1&nbsp;&nbsp; &nbsp; &nbsp;&nbsp; +7&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +2&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +2&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; +3 KMnO4&nbsp;&nbsp; +&nbsp; &nbsp; &nbsp;&nbsp; FeSO4&nbsp;&nbsp; +&nbsp;&nbsp; H2SO4&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; MnSO4&nbsp;&nbsp; +&nbsp;&nbsp; Fe2(SO4)3&nbsp;&nbsp; +&nbsp; &nbsp; K2SO4&nbsp;&nbsp; +&nbsp;&nbsp; H2O Chất oxi hóa&nbsp; Chất khử&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; +7&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +2 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 2&nbsp; &nbsp; Mn&nbsp; &nbsp; +5e-&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; Mn&nbsp; &nbsp; &nbsp; (phản ứng khử)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; +2&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +3 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 5&nbsp;&nbsp; 2Fe&nbsp; &nbsp;&nbsp; -2e-&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 2Fe&nbsp; &nbsp;&nbsp; (Phản ứng oxi hóa) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; (+4)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; (+6) 2KMnO4&nbsp;&nbsp; +&nbsp; 10FeSO4&nbsp;&nbsp; +&nbsp;&nbsp; H2SO4&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 2MnSO4&nbsp; +&nbsp; 5Fe2(SO4)3&nbsp; +&nbsp;&nbsp; K2SO4&nbsp;&nbsp; +&nbsp; H2O Giaùo khoa hoùa voâ cô&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Bieân soaïn: Voõ Hoàng Thaùi © Võ Hồng Thái222KMnO4&nbsp; +&nbsp; 10FeSO4&nbsp; +&nbsp; 8H2SO4&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 2MnSO4&nbsp; +&nbsp; 5Fe2(SO4)3&nbsp;&nbsp; +&nbsp;&nbsp; K2SO4&nbsp; +&nbsp; 8H2O Thí dụ 2:&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +8/3&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +5&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +3&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; +2 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Fe3O4&nbsp; &nbsp;&nbsp; +&nbsp; &nbsp;&nbsp; HNO3&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Fe(NO3)3&nbsp; &nbsp; +&nbsp;&nbsp; NO&nbsp; &nbsp; +&nbsp; &nbsp; H2O &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Chất khử&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; Chất oxi hóa&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; +8/3&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; +3 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 3&nbsp;&nbsp; 3Fe&nbsp;&nbsp; -&nbsp; e-&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 3Fe&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (Phản ứng oxi hóa) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; (+8)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (+9) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; +5&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +2 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; N&nbsp; &nbsp; +&nbsp;&nbsp; 3e-&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; N&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; (Phản ứng khử) &nbsp; &nbsp;&nbsp; &nbsp; &nbsp;&nbsp; 3Fe3O4&nbsp; &nbsp; +&nbsp; &nbsp;&nbsp; HNO3&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 9Fe(NO3)3&nbsp; &nbsp;&nbsp; +&nbsp; &nbsp; NO&nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +&nbsp; &nbsp;&nbsp; H2O &nbsp; &nbsp; &nbsp; &nbsp;3Fe3O4&nbsp; &nbsp; +&nbsp; &nbsp;&nbsp; 28HNO3&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 9Fe(NO3)3&nbsp; &nbsp; +&nbsp; &nbsp;&nbsp; NO&nbsp; &nbsp; +&nbsp; &nbsp; &nbsp; 14H2O&nbsp; [ Trong 28 phân tử HNO3 của tác chất, chỉ có 1 phân tử là chất oxi hóa thật sự, còn 27 phân tử&nbsp; tham gia trao đổi (tạo môi trường axit, tạo muối nitrat)] Thí dụ 3: &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; +2&nbsp;&nbsp; -1&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 0&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +3&nbsp; &nbsp;&nbsp; -2&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +4&nbsp; -2 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; FeS2&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; +&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; O2&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; Fe2O3&nbsp; &nbsp; &nbsp;&nbsp; +&nbsp; &nbsp; &nbsp;&nbsp; SO2&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Chất khử&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; Chất oxi hóa&nbsp; &nbsp; &nbsp; &nbsp; Pirit sắt, Sắt (II) pesunfua&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; +2&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; +3 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 2Fe&nbsp; &nbsp; -2e-&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 2Fe&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (Phản ứng oxi hóa) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (+4)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; (+6) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 2&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; -22e-&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; -1&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +4 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 4S&nbsp;&nbsp; - 20e-&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 4S&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; (Phản ứng oxi hóa) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (-4)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (+16) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 0&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; -2 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 11&nbsp; O 2&nbsp; &nbsp; &nbsp;&nbsp; + 4e-&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 2O&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (Phản ứng khử) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; (0)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (-4) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 4FeS2&nbsp; &nbsp;&nbsp; +&nbsp; &nbsp; 11O2&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; t0&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 2Fe2O3&nbsp; &nbsp; +&nbsp; &nbsp; 8SO2Thí dụ&nbsp; 4:&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +2y/x&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; +5&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +3&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; +2 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; FexOy&nbsp; &nbsp;&nbsp; +&nbsp; &nbsp;&nbsp; HNO3&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Fe(NO3)3&nbsp; &nbsp;&nbsp; +&nbsp; &nbsp; &nbsp; NO&nbsp; &nbsp; &nbsp; +&nbsp; &nbsp; &nbsp;&nbsp; H2O &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Chất khử&nbsp;&nbsp; ⇐&nbsp;&nbsp; Chất oxi hóa &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; +2y/x&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +3 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 3&nbsp; &nbsp; &nbsp; xFe&nbsp; &nbsp;&nbsp; - (3x-2y)e-&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; xFe&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (Phản ứng oxi hóa)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; (+2y)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (+3x)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +5&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +2 &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; (3x-2y)&nbsp; &nbsp; &nbsp; &nbsp; N&nbsp; &nbsp; &nbsp; +3e-&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; N&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (Phản ứng khử)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Giaùo khoa hoùa voâ cô&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Bieân soaïn: Voõ Hoàng Thaùi &nbsp;Võ Hồng Thái23&nbsp; &nbsp; &nbsp;&nbsp; 3FexOy&nbsp;&nbsp; +&nbsp; &nbsp; (3x-2y)HNO3&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 3xFe(NO3)3&nbsp; &nbsp; +&nbsp; &nbsp; (3x-2y)NO&nbsp;&nbsp; +&nbsp;&nbsp; H2O &nbsp; &nbsp; &nbsp; 3FexOy&nbsp;&nbsp; +&nbsp;&nbsp; (12x-2y)HNO3&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 3xFe(NO3)3&nbsp; &nbsp; +&nbsp;&nbsp; (3x-2y)NO&nbsp;&nbsp; +&nbsp;&nbsp; (6x-y)H2O Thí dụ 5:&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +2y/x&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +5&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +1 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; MxOy&nbsp; &nbsp; +&nbsp; &nbsp; HNO3&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; M(NO3)n&nbsp; &nbsp; +&nbsp; &nbsp; N2O&nbsp; &nbsp; +&nbsp; &nbsp; H2O &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; chất khử&nbsp;&nbsp; ⇐&nbsp;&nbsp; chất oxi hóa &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +2y/x&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; +n &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 8&nbsp; &nbsp;&nbsp; xM&nbsp; &nbsp; - (nx-2y)e-&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; xM&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (Phản ứng oxi hóa)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (+2y)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; (+nx) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +5&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +1 &nbsp; &nbsp; (nx-2y)&nbsp; &nbsp; 2N&nbsp; &nbsp;&nbsp; + 8e-&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 2N&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (Phản ứng khử)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (+10)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; (+2) &nbsp; &nbsp; &nbsp; &nbsp; 8MxOy&nbsp; &nbsp; +&nbsp; (2nx-4y)HNO3&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 8xM(NO3)n&nbsp;&nbsp; +&nbsp; &nbsp; (nx-2y)N2O&nbsp; &nbsp; +&nbsp; &nbsp;&nbsp; H2O &nbsp; &nbsp; 8MxOy&nbsp;&nbsp; +&nbsp;&nbsp; (10nx-4y)HNO3&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 8xM(NO3)n&nbsp;&nbsp; +&nbsp;&nbsp; (nx-2y)N2O&nbsp;&nbsp; +&nbsp;&nbsp; (5nx-2y)H2O &nbsp;&nbsp; [ (2nx - 4y) phân tử HNO3 là chất oxi hóa thật sự, nó bị khử&nbsp; tạo (nx-2y) phân tử N2O; còn (10nx-4y) - (2nx- 4y) = 8nx phân tử HNO3 tham gia trao&nbsp; đổi, tạo môi trường axit, tạo muối nitrat, trong đó số oxi hóa của N không đổi] Thí dụ&nbsp; 6:&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 0&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +5&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; +3&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +2&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; +1 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Al&nbsp; &nbsp; &nbsp; +&nbsp; &nbsp; &nbsp; HNO3&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; Al(NO3)3&nbsp; &nbsp; +&nbsp; &nbsp; xNO&nbsp; &nbsp; +&nbsp; &nbsp; yN2O&nbsp;&nbsp; +&nbsp;&nbsp; H2O&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Chất khử&nbsp; &nbsp;&nbsp; Chất oxi hóa&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 0&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; +3 &nbsp; &nbsp;&nbsp; (3x+8y)&nbsp; &nbsp; &nbsp; Al&nbsp; &nbsp;&nbsp; -3e-&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; Al&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (Phản ứng oxi hóa) +5&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +2 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; xN&nbsp; &nbsp;&nbsp; +3xe-&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; xN&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (Phản ứng khử) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (+5x)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; (+2x)&nbsp;&nbsp; &nbsp; &nbsp; 3&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; + (3x+8y) e-&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; +5&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; +1 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 2yN&nbsp; &nbsp;&nbsp; +8ye-&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 2yN&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (Phản ứng khử) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (+10y)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; (+2y) &nbsp; (3x+8y)Al&nbsp; +&nbsp; (3x+6y)HNO3&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (3x+8y)Al(NO3)3&nbsp; +&nbsp; 3xNO&nbsp; + 3yN2O&nbsp;&nbsp; +&nbsp; H2O (3x +8y)Al +(12x+30y)HNO3&nbsp; &nbsp; &nbsp; &nbsp; (3x+8y)Al(NO3)3 + 3xNO + 3yN2O + (6x+15)H2OGiaùo khoa hoùa voâ cô&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Bieân soaïn: Voõ Hoàng Thaùi © Võ Hồng Thái24Thí dụ 7:&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; +2y/x&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +2&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +2m/n&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +4 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; FexOy&nbsp; &nbsp; &nbsp;&nbsp; +&nbsp; CO&nbsp; &nbsp; &nbsp; &nbsp;&nbsp; t0&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; FenOm&nbsp;&nbsp; +&nbsp;&nbsp; CO2&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; Chất oxi hóa&nbsp; &nbsp; ⇐&nbsp; Chất khử&nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +2y/x&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +2m/n &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; nxFe&nbsp; &nbsp; +&nbsp;&nbsp; (2ny-2mx)e-&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; nxFe&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; (Phản ứng khử)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (+2ny)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; (+2mx) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; +2&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +4 &nbsp;(ny-mx)&nbsp; &nbsp; &nbsp;&nbsp; C&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; -2e-&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; C&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; (Phản ứng oxi hóa)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; nFexOy&nbsp; &nbsp; &nbsp; +&nbsp; &nbsp; (ny-mx)CO&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; xFenOm&nbsp; &nbsp; +&nbsp; &nbsp;&nbsp; (ny-mx)CO2Thí dụ&nbsp; 8:&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +8/3&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +5&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; +3&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; +2y/x &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; Fe3O4&nbsp; &nbsp; +&nbsp; &nbsp; HNO3&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; Fe(NO3)3&nbsp; &nbsp; +&nbsp; &nbsp; NxOy&nbsp; &nbsp; +&nbsp; &nbsp; H2O &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Chất khử&nbsp; &nbsp; &nbsp; &nbsp; Chất oxi hóa&nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; +8/3&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +3 &nbsp; (5x-2y)&nbsp; &nbsp; 3Fe&nbsp; &nbsp; &nbsp; &nbsp; -&nbsp; e-&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 3Fe&nbsp; &nbsp; &nbsp; &nbsp;&nbsp; (Phản ứng oxi hóa)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (+8)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (+9) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; +5&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; +2y/x &nbsp; &nbsp; &nbsp; &nbsp; xN&nbsp; &nbsp; &nbsp; &nbsp; +&nbsp;&nbsp; (5x-2y)e-&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; xN&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; (Phản ứng khử)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; (+5x)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (+2y) &nbsp;&nbsp; (5x-2y)Fe3O4&nbsp; &nbsp; +&nbsp; &nbsp;&nbsp; xHNO3&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; (15x-6y)Fe(NO3)3&nbsp;&nbsp; +&nbsp; &nbsp; &nbsp; NxOy&nbsp; &nbsp;&nbsp; +&nbsp; &nbsp; H2O (5x-2y)Fe3O4 + (46x-18y)HNO3&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (15x-6y)Fe(NO3)3&nbsp; +&nbsp; NxOy&nbsp; +&nbsp; (23x-9y)H2O</blockquote>

[QUOTE="vanhieu1995, post: 117364, member: 109931"] [CENTER][SIZE=4][COLOR=#ff0000]Tuyển tập tất cả các phương pháp cân bằng phản ứng oxi hóa khử -có so sánh các phương pháp. [/COLOR][/SIZE][f=800]https://server1.vnkienthuc.com/files/815/04-phuongphapcanbangpuoxihoakhu.pdf[/f][/CENTER] Nguyên tắc chung để cân bằng phản ứng oxi hóa khử là số điện tử cho của chất khử phải bằng số điện tử nhận của chất oxi hóa hay số oxi hóa tăng của chất khử phải bằng số oxi hóa giảm của chất oxi hóa. III.1. PHƯƠNG PHÁP CÂN BẰNG ĐIỆN TỬ (THĂNG BẰNG ELECTRON) Thực hiện các giai đoạn: + Viết phương trình phản ứng xảy ra với đầy đủ tác chất, sản phẩm (nếu đầu bài yêu cầu bổ sung phản ứng, rồi mới cân bằng). + Tính số oxi hóa của nguyên tố có số oxi hóa thay đổi. Nhận diện chất oxi hóa, chất khử. + Viết phản ứng cho, phản ứng nhận điện tử (Phản ứng oxi hóa, phản ứng khử). Chỉ cần viết nguyên tử của nguyên tố có số oxi hóa thay đổi, với số oxi hóa được để bên trên. Thêm hệ số thích hợp để số nguyên tử của nguyên tố có số oxi hóa thay đổi hai bên bằng nhau. + Cân bằng số điện tử cho, nhận. Số điện tử cho của chất khử bằng số điện tử nhận của chất oxi hóa (Hay số oxi hóa tăng của chất khử bằng số oxi hóa giảm của chất oxi hóa) bằng cách thêm hệ số thích hợp. + Phối hợp các phản ứng cho, nhận điện tử; các hệ số cân bằng tìm được; và phản ứng lúc đầu để bổ sung hệ số thích hợp vào phản ứng lúc đầu. + Cuối cùng cân bằng các nguyên tố còn lại (nếu có) như phản ứng trao đổi. Các thí dụ: Cân bằng các phản ứng sau đây theo phương pháp cân bằng điện tử. Thí dụ 1 +7 +2 +2 +3 KMnO4 + FeSO4 + H2SO4 MnSO4 + Fe2(SO4)3 + K2SO4 + H2O Chất oxi hóa Chất khử +7 +2 2 Mn +5e - Mn (phản ứng khử) +2 +3 5 2Fe -2e - 2Fe (Phản ứng oxi hóa) (+4) (+6) 2KMnO4 + 10FeSO4 + H2SO4 2MnSO4 + 5Fe2(SO4)3 + K2SO4 + H2O Giaùo khoa hoùa voâ cô Bieân soaïn: Voõ Hoàng Thaùi © Võ Hồng Thái 22 2KMnO4 + 10FeSO4 + 8H2SO4 2MnSO4 + 5Fe2(SO4)3 + K2SO4 + 8H2O Thí dụ 2: +8/3 +5 +3 +2 Fe3O4 + HNO3 Fe(NO3)3 + NO + H2O Chất khử Chất oxi hóa +8/3 +3 3 3Fe - e - 3Fe (Phản ứng oxi hóa) (+8) (+9) +5 +2 N + 3e - N (Phản ứng khử) 3Fe3O4 + HNO3 9Fe(NO3)3 + NO + H2O 3Fe3O4 + 28HNO3 9Fe(NO3)3 + NO + 14H2O [ Trong 28 phân tử HNO3 của tác chất, chỉ có 1 phân tử là chất oxi hóa thật sự, còn 27 phân tử tham gia trao đổi (tạo môi trường axit, tạo muối nitrat)] Thí dụ 3: +2 -1 0 +3 -2 +4 -2 FeS2 + O2 Fe2O3 + SO2 Chất khử Chất oxi hóa Pirit sắt, Sắt (II) pesunfua +2 +3 2Fe -2e - 2Fe (Phản ứng oxi hóa) (+4) (+6) 2 -22e - -1 +4 4S - 20e - 4S (Phản ứng oxi hóa) (-4) (+16) 0 -2 11 O 2 + 4e- 2O (Phản ứng khử) (0) (-4) 4FeS2 + 11O2 t 0 2Fe2O3 + 8SO2 Thí dụ 4: +2y/x +5 +3 +2 FexOy + HNO3 Fe(NO3)3 + NO + H2O Chất khử ⇐ Chất oxi hóa +2y/x +3 3 xFe - (3x-2y)e - xFe (Phản ứng oxi hóa) (+2y) (+3x) +5 +2 (3x-2y) N +3e - N (Phản ứng khử) Giaùo khoa hoùa voâ cô Bieân soaïn: Voõ Hoàng Thaùi Võ Hồng Thái 23 3FexOy + (3x-2y)HNO3 3xFe(NO3)3 + (3x-2y)NO + H2O 3FexOy + (12x-2y)HNO3 3xFe(NO3)3 + (3x-2y)NO + (6x-y)H2O Thí dụ 5: +2y/x +5 +n +1 MxOy + HNO3 M(NO3)n + N2O + H2O chất khử ⇐ chất oxi hóa +2y/x +n 8 xM - (nx-2y)e - xM (Phản ứng oxi hóa) (+2y) (+nx) +5 +1 (nx-2y) 2N + 8e - 2N (Phản ứng khử) (+10) (+2) 8MxOy + (2nx-4y)HNO3 8xM(NO3)n + (nx-2y)N2O + H2O 8MxOy + (10nx-4y)HNO3 8xM(NO3)n + (nx-2y)N2O + (5nx-2y)H2O [ (2nx - 4y) phân tử HNO3 là chất oxi hóa thật sự, nó bị khử tạo (nx-2y) phân tử N2O; còn (10nx-4y) - (2nx- 4y) = 8nx phân tử HNO3 tham gia trao đổi, tạo môi trường axit, tạo muối nitrat, trong đó số oxi hóa của N không đổi] Thí dụ 6: 0 +5 +3 +2 +1 Al + HNO3 Al(NO3)3 + xNO + yN2O + H2O Chất khử Chất oxi hóa 0 +3 (3x+8y) Al -3e - Al (Phản ứng oxi hóa) +5 +2 xN +3xe - xN (Phản ứng khử) (+5x) (+2x) 3 + (3x+8y) e - +5 +1 2yN +8ye - 2yN (Phản ứng khử) (+10y) (+2y) (3x+8y)Al + (3x+6y)HNO3 (3x+8y)Al(NO3)3 + 3xNO + 3yN2O + H2O (3x +8y)Al +(12x+30y)HNO3 (3x+8y)Al(NO3)3 + 3xNO + 3yN2O + (6x+15)H2OGiaùo khoa hoùa voâ cô Bieân soaïn: Voõ Hoàng Thaùi © Võ Hồng Thái 24 Thí dụ 7: +2y/x +2 +2m/n +4 FexOy + CO t 0 FenOm + CO2 Chất oxi hóa ⇐ Chất khử +2y/x +2m/n nxFe + (2ny-2mx)e - nxFe (Phản ứng khử) (+2ny) (+2mx) +2 +4 (ny-mx) C -2e - C (Phản ứng oxi hóa) nFexOy + (ny-mx)CO xFenOm + (ny-mx)CO2 Thí dụ 8: +8/3 +5 +3 +2y/x Fe3O4 + HNO3 Fe(NO3)3 + NxOy + H2O Chất khử Chất oxi hóa +8/3 +3 (5x-2y) 3Fe - e - 3Fe (Phản ứng oxi hóa) (+8) (+9) +5 +2y/x xN + (5x-2y)e - xN (Phản ứng khử) (+5x) (+2y) (5x-2y)Fe3O4 + xHNO3 (15x-6y)Fe(NO3)3 + NxOy + H2O (5x-2y)Fe3O4 + (46x-18y)HNO3 (15x-6y)Fe(NO3)3 + NxOy + (23x-9y)H2O [/QUOTE]

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