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Chemical Reactions and Acids/Bases

Chemical Reactions and Acids/Bases. Physical Science. Chemical Reactions. When 2 or more elements chemically combine to form a “ new ” substance. Chemical Equation. Is a representation of a chemical reaction Two Parts Reactants Products. Reactants vs Products. C + O 2  CO 2

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Chemical Reactions and Acids/Bases

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  1. Chemical Reactions and Acids/Bases Physical Science

  2. Chemical Reactions • When 2 or more elements chemically combine to form a “new” substance

  3. Chemical Equation • Is a representation of a chemical reaction • Two Parts • Reactants • Products

  4. Reactants vs Products C + O2 CO2 The arrow () divides an equation in half Products The new substance(s) that form All things on the right side of the “” Ex: CO2 • Reactants • The substance(s) that undergo the change • All things on the left side of the “” • Ex: C & O2

  5. Id the Reactants and Products • 2Cu + O2 2CuO • 2KClO3  2KCl + 3O2 • HCl + NaOH  NaCl + H2O • N2H4 + O2  N2 + 2H2O

  6. Endothermic vs Exothermic • Endothermic • Reaction absorbs energy from its surrounding • Surrounding becomes warmer • Exothermic • Reaction releases energy to the surrounding • Surrounding becomes warmer

  7. Signs of a Reaction • Production of a GAS • Fizzing, bubbling • Formation of a Precipitate • Insoluble solid • Energy is released • Light, heat • Color Change

  8. Counting Atoms • Number in front is called a coefficient • Coefficients are multiplied to all elements behind it • Subscripts go to what they just follow

  9. Counting Atoms Practice • 2CO2 • Mg(OH)2 • 3Ca(NO3)2 • NH4OH

  10. How Do I Balance an Equation? • Id the elements present • Count the amount of atoms on both sides of the “” for each element • Place coefficients in front of compounds and multiply to any subscript • Recount the atoms to see if they are equal

  11. Balancing Practice #1 ____Cu + ____O2 ____CuO

  12. Balancing Practice #2 ____N2H4 + ____O2 ____N2 + ____H2O

  13. Balancing Practice #3 ____KClO3 ____KCl + ____O2

  14. Why Balance? • The Law of Conservation of Matter • Matter is neither created nor destroyed • Start = Finish

  15. Types of Reactions • 4 Main Types • Synthesis • Decomposition • Single Replacement • Double Replacement • 2 Special Types • Combustion Reaction • Neutralization Reaction

  16. Synthesis ReactionA + B  AB • When 2 or more substances react to form a single substance • 21 • Dating: Becoming a Couple

  17. Decomposition ReactionAB  A + B • When a compound breaks down into two or more substances • 12 • Dating: Breaking Up

  18. Single Replacement ReactionA + BC  B + AC • A reaction in which one element trades places with another element in a compound • Element and Compound  Element and Compound • Dating: CHEATING

  19. Double Replacement ReactionAB + CD  AD + BD • Where two different compounds exchange positive ions (cations) to form two new compounds • All compounds • (4 of them) • Dating: Swingers

  20. Type Of Reaction Practice • Na3PO4 + 3KOH  3NaOH + K3PO4 • P4 + 3O2  2P2O3 • Pb + FeSO4  PbSO4 + Fe • CaCO3  CaO + CO2

  21. Special Reaction: Combustion Reaction • When a hydrocarbon (hydrogen and carbon together) reacts with Oxygen • Products are always CO2 & H2O • Ex: CH4 + 2O2 CO2 + H2O

  22. Acids • Compounds that produces hydronium (H+) ions when dissolved in water • Formula start with “H”

  23. Acid Properties • Sour Taste • Reacts violently with metals • Electrolyte • Burns the skin

  24. Common Acids • Hydrochloric Acid—HCl • Sulfuric Acid—H2SO4 • Nitric Acid—HNO3 • Citric Acid—C6H8O7 • Acetic Acid—CH3COOH

  25. Bases • Compound that produces hydroxide (OH--) ions when dissolved in water • Formula ends in “OH”

  26. Base Properties • Bitter Taste • Slippery Feel • Will burn the skin

  27. Common Bases • Calcium Hydroxide—Ca(OH)2 • Magnesium Hydroxide—Mg(OH)2 • Sodium Hydroxide--NaOH

  28. How to Determine If A Compound is an Acid or Base? • ACID’s Formula starts with “H” • BASE’s Formula end in “OH” • If it does neither then it is a SALT

  29. Acid, Base or Salt? • LiOH • HCl • NaCl • NH4OH • Ca3(PO4)2 • H2SO4

  30. Special Reaction:Neutralization Reaction • When a reaction between an ACID and a BASE produced A SALT and WATER • A Double Replacement Reaction HCl + NaOH NaCl + H2O

  31. pH Scale • Used to determine how acidic or basic something is • From 0—14 (number line) • Acid Range: 0—6 • Strong Acid: 0—2 • Base Range: 8—14 • Strong Base: 10—14 • Water has a pH of 7 (neutral)

  32. Indicators • Blue Litmus Paper • Acid—turns Red • Base—no change • Red Litmus Paper • Acid—no change • Base—turns Blue

  33. Indicators • pHPaper • Acid—turns red, orange, yellow tints • Base—turns blue-green to dark blue tints • Phenolphthalein • Acid—stays clear • Base—turns hot pink

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