1 / 12

Chemical Equations

Chemical reactions involve the transformation of reactants into products, obeying the law of conservation of mass. This guide covers the basics of chemical equations, emphasizing the importance of balancing reactions. It introduces three main types: synthesis (where elements combine), decomposition (where compounds break down), and combustion (reaction with oxygen). We provide key examples and strategies for balancing equations, ensuring all reactions conform to chemical principles. Enhance your understanding of these fundamental concepts in chemistry.

thwaite
Télécharger la présentation

Chemical Equations

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chemical Equations These interactions are called chemical reactions. A substance that undergoes a chemical reaction is called a reactant. A substance that is formed in a chemical reaction is called a product.

  2. The law of conservation of mass states that in any chemical reaction, the mass of the products is always equal to the mass of the reactants. • Thus we must balance the reactions.

  3. Balance metals, followed by non-metals, and then polyatomic ions if they are located on both sides. • Balance the hydrogens. • Finally balance the oxygens. • Verify all values.

  4. Synthesis Reactions • In a synthesis reaction, two or more elements or compounds combine to form a new substance. A + B → C

  5. Synthesis Reactions • 2 H2(g) + O2(g) → 2 H2O(g) • 2 Mg(s) + O2(g) → 2 MgO(s) • 2 K(s) + Cl2(g) → 2 KCl(s) • 4 Fe(s) + 3 O2(g) → 2 Fe2O3(s) Must look at charges to make compounds!

  6. Synthesis Reactions • When a non-metallic oxide reacts with water, the product is an acid. • SO3(g) + H2O(l) → H2SO4(aq) • Conversely, when a metallic oxide reacts with water, the product is a metal hydroxide. • CaO(s) + H2O(l) → Ca(OH)2(aq)

  7. Decomposition Reactions • In a decomposition reaction, a compound breaks down into elements or other compounds. Therefore, a decomposition reaction is the opposite of a synthesis reaction. C → A + B

  8. Decomposition Reactions • 2 H2O → 2 H2 + O2 • NH4NO3(s) → N2O(g) + 2 H2O(g) • Generally decompose into elemental form, but maybe some compounds.

  9. Decomposition Reactions • Carbonates decompose into carbon dioxide and a metal oxide: • MgCO3(s) CO2(g) + MgO(s) • Hydroxides decompose into water and a metal oxide: • Ca(OH)2(s) H2O(l) + CaO(s)

  10. Decomposition Reactions • Chlorates decompose into oxygen and a metal halide: • 2 KClO3(s) 3 O2(g) + 2 KCl(s)

  11. Combustion Reactions • A combustion reaction occurs when a compound reacts in the presence of oxygen to form oxides and energy. • S8(s) + 8 O2(g) → 8 SO2(g) • Complete combustion of a hydrocarbon occurs when the hydrocarbon reacts completely in the presence of sufficient oxygen. The complete combustion of a hydrocarbon produces only water vapour and carbon dioxide gas as products. • C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(g)

  12. Incomplete combustion of a hydrocarbon occurs when there is not enough oxygen present for the hydrocarbon to react completely. The incomplete combustion of a hydrocarbon produces water, carbon dioxide, carbon monoxide, and solid carbon in varying amounts. • 2 C3H8(g) + 7 O2(g) → 2 CO2(g) + 8 H2O(g) + 2 CO(g) + 2 C(s)

More Related