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Chemical Reactions

Chemical Reactions. Review Chemical Reactions Types of Reactions Controlling Reactions Rates of Reactions Acids and Bases pH level. Review. Difference between chemical vs physical change.. Tarnish Melting Glass Breaks Rusting Burning Nail magnetized Sugar dissolving

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Chemical Reactions

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  1. Chemical Reactions • Review • Chemical Reactions • Types of Reactions • Controlling Reactions • Rates of Reactions • Acids and Bases • pH level

  2. Review • Difference between chemical vs physical change.. • Tarnish • Melting • Glass Breaks • Rusting • Burning • Nail magnetized • Sugar dissolving • Antacid neutralizes gas

  3. Chemical vs Physical • Difference between chemical vs physical change.. • Tarnish 2 Ag + S Ag2S • Melting H2O • Glass Breaks SiO2 • Rusting 4 Fe + 3 O2 2 FE2O3 • Burning CH4 + 2 O2 2 H2O + CO2 • Nail magnetized Fe • Sugar dissolving sugar + water • Antacid neutralizes acid Ca(OH)2 + 2 HCl CaCl2 + 2 H2O

  4. Chemical Reactions • Change in Substance • Change of composition • New properties • Change in Energy • Exothermic - releases energy (heat) • Endothermic - absorbs energy (heat) A + B C A,B = reactants C = product

  5. Types of Reactions • 1) Synthesis A + B AB • 4 H + O2 2 H2O • 2) Decomposition AB A + B • 2H2O2 2 H2O + O2 • 3) Replacement • Single AX + B A + BX • 2 Cu2O + C 4 Cu + CO2 • Double AB + CD AC + BD • FeS + 2 HCl FeCl2 + H2S • 4) Oxidation A + O AO + energy • CH4 + 2 O2 2 H2O + CO2 + Heat • 5) Neutralization (discussed later)

  6. Controlling Reactions • 1) Activation Energy • 2) Energy Difference • Exothermic • Endothermic

  7. Rates of Reactions • 1) Temperature • 2) Concentration [ ] • 3) Catalyst • Material which increases rate of reaction by lowering activation energy (not affected by the reaction)

  8. Acids and Bases • Acid – donates protons • H1+ Hydrogen ion • Sour, burn, corrode, digest, lemon • Base – accepts protons (can also be called akaline) • OH 1- Hydroxide ion • Bitter, slippery, soap, baking soda • Neutralization • acid + base = water + salt • HCl + NaOH H2O + Na+(aq) + Cl-(aq) • Measured by pH

  9. Power of Hydrogen p[H] or pH • Solution: a liquid with another substance dissolved with in the liquid • pH is a measure of the acidity or alkalinity(base) of a solution. It is based on the concentration of dissolved hydrogen ions (H+). • Measured by pH paper or litmus paper • Red = acid • Blue = base • Scale of 1 – 14 • pH 1 strong acid • pH 14 strong base • pH 7 neutral

  10. Nomenclature-7 Acids and 1 Base Hydrochloric acid HCL Nitric acid HNO3 Acetic acid HC2H3O2 Perchloric acid HClO4 Carbonic acid HCO3 Sulfuric acid H2SO4 Phosphoric acid H3PO4 Ammonia NH3

  11. Describing the Chemical Reaction between Baking Soda and Vinegar Baking soda, a pure chemical called sodium bicarbonate, has the chemical formula: NaHCO3When dissolved in water baking soda separates into sodium (Na+) and bicarbonate ions (HCO3- ): NaHCO3 ---> Na+(aq) + HCO3-(aq) Vinegar, a weak (5%) solution of acetic acid in water, partially dissociates into hydrogen ( H+) and acetate ions (CH3COO-): CH3COOH <--> H+(aq) + CH3COO-(aq) The reaction between baking soda and vinegar is actually two reactions, an acid base reaction followed by a decomposition reaction.When the two ingredients are mixed, hydrogen ions ( H+) from the vinegar react with the bicarbonate ions (HCO3- ) from the baking soda to form a new chemical called carbonic acid (H2CO3). H+ + HCO3- ---> H2CO3 The carbonic acid thus formed then immediately decomposes into carbon dioxide gas (CO2)and water (H2O). H2CO3 ---> H2O + CO2 It's this carbon dioxide gas that you see bubbling and foaming as soon as you mix baking soda and vinegar together.Using the molecular structures of only the components involved, the chemical reaction can be written: The overall reaction however, is often written as follows: NaHCO3 (aq) + CH3COOH (aq) ----> CO2 (g) + H2O (l) + CH3COONa (aq)

  12. Baking soda and vinegar chemical reaction overview

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