1 / 22

Chemical Reactions and Evidence

Chemical Reactions and Evidence. Physical Science. A) Chemical Reactions. Chemical Reaction- the process that turns one set of chemical substances into another one set Chemical reactions are studied by specialized scientist called chemist- they study all things atomic

colm
Download Presentation

Chemical Reactions and Evidence

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 Reactions and Evidence Physical Science

  2. A) Chemical Reactions • Chemical Reaction- the process that turns one set of chemical substances into another one set • Chemical reactions are studied by specialized scientist called chemist-they study all things atomic • Antoine-Laurent de Lavoisier is considered to be the father of modern chemistry, thanks to his intensive study of reactions during the mid 1700’s • Was the first to publish the law of conservation of mass • The total mass of things that go into a reaction(products) equals the total mass of all things that are produced during the reaction(products) • Mass is neither created or destroyed in a RXN, it only changes forms

  3. How do we know when a chemical reaction has taken place? Absorb or Release of Heat -gets hot or gets cold or releases light ? Production of a Gas -can you smell it, like something rotting? -do you see bubbles in the liquid? Formation of a solid, called a precipitate -it “rains” or precipitates out of the solution -it is usually a different color?

  4. Chemical Vs. Physical Change • Physical changes are only concerned with changes in energy or states of matter ( S,L,G) • Starting and ending material are the same thing, thought they may look different • EX- Ice melting, Water evaporating

  5. B) Writing Chemical Reactions When a clear aqueous solution of potassium iodide is mixed with a clear aqueous solution of lead nitrate it produces(yields ) a clear solution of potassium nitrate and a yellow solid precipitate called lead(II) iodide Pb(NO3)2(aq) + KI(aq)  PbI2(s) + KNO3(aq) Reactants Products

  6. Symbols Used in an Equation • (g) means gaseous phase • (l) means liquid phase • (s) means solid phase • (aq) means dissolved in water • means yield (produces)

  7. Writing Word Equations • Aqueous silver nitrate reacts with solid copper metal to form solid silver and copper (II) nitrate.

  8. Types of Chemical Reactions • Synthesis or Combination • Two or more substances chemically combine to become one substance • Pattern A + B AB + • Mg + Cl2 MgCl2 _

  9. Types of Rxns. Cont… • Decomposition • One substance breaks down into two or more substances. • Pattern • AB A + B + MgCl2 Mg + Cl2

  10. Types of Rxns. Cont. • Single Replacement • When a single element switches placement with the anion or cation of another compound • Pattern • AB + C AC + B • + + • NaCl + K Na + KCl

  11. Types of Rxns. Cont. • Double Replacement • When the cations and anions of two different compounds switch places • Pattern • AB + CD AD + CB • + + • KCl + MgOH KOH + MgCl2

  12. Pb(NO3)2(aq) + KI(aq)  PbI2(s) + KNO3(Aq) Reactants Pb- N- O- K- I- Products Pb- N- O- K- I- 1 2 6 1 1 1 1 3 1 2

  13. C) Balancing Chemical Equations The conservation of mass says that you must equal amounts of reactants and products You can never change the chemical formulas in the equation *DO NOT CHANGE THE CHEMICAL FORMULAS* You can only alter the equation to balance it by adding coefficients, big numbers in from of a chemical formula to make everything equal ___Pb(NO3)2(aq) + ___KI(aq)  ___PbI2(s) + ____KNO3(Aq)

  14. ___Pb(NO3)2(aq) + ___KI(aq)  ___PbI2(s) +____KNO3(Aq) Reactants Pb- N- O- K- I- Products Pb- N- O- K- I- 1 2 6 1 1 1 1 3 1 2

  15. 2 ___Pb(NO3)2(aq) + ___KI(aq)  ___PbI2(s) +____KNO3(Aq) Reactants Pb- N- O- K- I- Products Pb- N- O- K- I- 1 2 6 2 2 1 1 3 1 2

  16. 2 2 ___Pb(NO3)2(aq) + ___KI(aq)  ___PbI2(s) +____KNO3(Aq) Reactants Pb- N- O- K- I- Products Pb- N- O- K- I- 1 2 6 2 2 1 2 6 2 2

  17. Pb(NO3)2(aq) + 2KI(aq)  PbI2(s) + 2KNO3(Aq) YAY!!! We Have a Balanced Equation

  18. Practice Equations SnO2 + H2 → Sn + H2O N2 + H2 → NH3 C3H8(g) + O2(g)  CO2(g)+ H2O(g) Na(s) + HCl(aq) → NaCl(aq) + H2(g)

  19. B4H10(g) + O2(g) -- B2O3(g) + H2O(g) Na3PO4 + Fe2O3 -- Na2O + FePO4 NaCl(aq) + AgNO3(aq) → NaNO3(aq) + AgCl(s)

More Related