Double-replacement reaction

AB + CD → AD + CB A and C are positive charged cations in this reaction, while B and D are negative charged anions. Double-replacement reactions typically occur in aqueous solution between the compounds. To cause a reaction, one of the products is usually a solid precipitate, a gas, or a molecular compound like water. A precipitate forms in a double-replacement reaction when the cations from one reactant combine to form an insoluble ionic compound with the anions from the other reactant. The following reaction occurs when aqueous solutions of potassium iodide and lead ( II) nitrate are blended.

• (NH₄)₂CO₃ + 2HCl → H₂O + 2NH₄Cl + CO₂
• (NH₄)₂S + CuSO₄ → (NH₄)₂SO₄ + CuS
• 2(NH₄)₃PO₄ + 3H₂SO₄ → 3(NH₄)₂SO₄ + 2H₃PO₄
• 3Ag₂SO₄ + 2FeCl₃ → 6AgCl + Fe₂(SO₄)₃
• 3AgNO₃ + AlCl₃ → 3AgCl + Al(NO₃)₃

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Oxidation-reduction reaction

An oxidation-reduction (redox) reaction is a type of chemical reaction that involves a transfer of electrons between two species. An oxidation-reduction reaction is any chemical reaction in which the oxidation number of a molecule, atom, or ion changes by gaining or losing an electron. Redox reactions are common and vital to some of the basic functions of life, including photosynthesis, respiration, combustion, and corrosion or rusting.

• Ag + 2HNO₃ → AgNO₃ + H₂O + NO₂
• 2Ag + O₃ → Ag₂O + O₂
• Ag₂O + H₂O₂ → 2Ag + H₂O + O₂
• Ag₂O + HCHO → 2Ag + HCOOH
• FeCl₂ + Ag₂SO₄ → 2AgCl + FeSO₄

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Decomposition reaction

Many decomposition reactions involve heat , light, or electricity to input energy. Binary compounds are compounds which consist of only two elements. The simplest sort of reaction to decomposition is when a binary compound breaks down into its elements. Mercury (II) oxide, a red solid, decomposes to form mercury and oxygen gas when heated. Also, a reaction is regarded as a decomposition reaction even if one or more of the products are still a compound. A metal carbonate breaks down to form a metal oxide and carbon dioxide gas. Calcium carbonate for example decomposes into calcium oxide and carbon dioxide.

• (NH₄)₂CO₃ → H₂O + 2NH₃ + CO₂
• (NH₄)₂Cr₂O₇ → 4H₂O + N₂ + Cr₂O₃
• (NH₄)₂SO₄ → H₂SO₄ + 2NH₃
• 2AgNO₃ → 2Ag + 2NO₂ + O₂
• 2Al(OH)₃ → Al₂O₃ + 3H₂O

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Combination reaction

Also known as a synthesis reaction. One kind of frequently occurring combination reaction is the reaction of an element with oxygen to form an oxide. Under certain conditions, metals and nonmetals both react readily with oxygen. Once ignited, magnesium reacts rapidly and dramatically, reacting with oxygen from the air to create a fine magnesium oxide powder.

• 2Al + 3Br₂ → 2AlBr₃
• 2Al + 3I₂ → 2AlI₃
• 4Al + 3O₂ → 2Al₂O₃
• BaO + CO₂ → BaCO₃
• BaO + H₂O → Ba(OH)₂

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Single-replacement reaction

A + BC → AC + B Element A is a metal in this general reaction and replaces element B, a metal in the compound as well. If the replacement element is a non-metal, it must replace another non-metal in a compound, and it becomes the general equation. Many metals easily react with acids, and one of the reaction products when they do so is hydrogen gas. Zinc reacts to the aqueous zinc chloride and hydrogen with hydrochloride acid (see figure below).

• 2AgNO₃ + Cu → 2Ag + Cu(NO₃)₂
• 2Al + 3CuCl₂ → 2AlCl₃ + 3Cu
• 2Al + 6HCl → 2AlCl₃ + 3H₂
• Al(OH)₃ + NaOH → 2H₂O + NaAlO₂
• 2AlCl₃ + 3Mg → 2Al + 3MgCl₂

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