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30 Nov. 2010 Law of Conservation of Mass

30 Nov. 2010 Law of Conservation of Mass. Objective : SWBAT demonstrate the law of conservation of mass and show it symbolically through the use of coefficients in a balanced chemical equation. Do now : How many atoms of each element? (This is not multiple choice!)

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30 Nov. 2010 Law of Conservation of Mass

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  1. 30 Nov. 2010Law of Conservation of Mass • Objective: SWBAT demonstrate the law of conservation of mass and show it symbolically through the use of coefficients in a balanced chemical equation. • Do now: How many atoms of each element? (This is not multiple choice!) a) NaNO3 b) Mg(NO3)2 c) 2H2O

  2. Agenda • Do now • Law of Conservation of Mass Notes • Practice Problems • Demonstration • Balancing Equations Examples • Practice problems Homework: Week 13 #1-15: Weds. Lab report 1st draft: Fri.

  3. Announcements • Did you miss the test on Wednesday? • Take it after school TODAY, or come see me to make other arrangements.

  4. Law of Conservation of Mass

  5. Big Picture If 5.00 grams of oxygen are reacted with 5.00 grams of hydrogen, what mass of water is formed? • Is there any oxygen or hydrogen left over? • Which one? • How much?

  6. Review of writing chemical equations • Remember: • (g) = gas (l) = liquid (s) = solid • (aq) = aqueous • Must use rules for naming/writing formulas • Ionic compounds – balance charges, NO prefixes • Covalent compounds – use prefixes

  7. Information from Chemical Equations • To produce fertilizers, Nitrogen gas is combined with Hydrogen gas to produce Nitrogen trihydride (ammonia). • N2(g) + H2(g)  NH3(g)

  8. Information from Chemical Equations • Making fertilizer uses a lot of energy and a lot of raw materials • Efficiency is key!! • How can knowledge about chemical reactions make This process as efficient as possible?

  9. CS2(l) + O2(g)  CO2(g) + SO2(g) Liquid carbon disulfide reacts with oxygen gas to produce carbon dioxide gas and sulfur dioxide gas. • Solid aluminum reacts with a solution of zinc chloride to produce solid zinc and a solution of aluminum chloride. Al(s) + ZnCl2(aq)  Zn(s) + AlCl3(aq)

  10. The Law of Conservation of Mass • In a chemical reaction, matter is never created or destroyed. • The number of atoms and the mass of the reactants must be equal to the number of atoms and the mass of the products.

  11. Demonstration • Solid sodium bicarbonate reacts with a solution of acetic acid to produce… • NaHCO3(s) + CH3COOH(aq)  CO2(g) + H2O(l) + NaCO3(aq) Initial mass: Final mass: Thoughts? Why doesn’t this reaction satisfy (obey) the law of conservation of mass?

  12. What could we do to make it satisfy the law of conservation of mass?

  13. More examples:Law of Conservation of Mass • CS2(l) + O2(g)  CO2(g) + SO2(g) • If I reacted 5 grams of CS2 with 5 grams of O2, and the reaction produced 2 grams of CO2, how many grams of SO2 must have been produced? • If my products had a total mass of 20 grams, how many grams of reactants must I have started with? • If I reacted 3 grams of CS2 with an unknown number of grams of O2 and produced a total of 4 grams of products, what was the mass of the O2?

  14. A: 30 Nov. 2010 • Take Out Homework: Week 13 #1-8 • Objective: SWBAT use coefficients to balance equations, satisfying the Law of Conservation of Mass • Do now: a) Write the formula equation: Hydrogen gas reacts with fluorine gas to produce hydrogen fluoride gas. b) If 3 grams of hydrogen gas is reacted with 2 grams of fluorine gas, how many grams of hydrogen fluoride gas are produced?

  15. Agenda • Do now, Homework solutions • Balancing Equations Examples • Practice Problems Homework: Week 13 #9-15 Lab report: Friday

  16. How do we show, in a chemical equation, that the law of conservation of mass is being obeyed? • The law of conservation of mass must be satisfied by equalizing the number of atoms on the reactant and the product sides. • Use coefficients to show how many molecules of each compound.

  17. Balancing Equations • H2(g) + F2(g)  HF(g) • H2(g) + F2(g)  HF(g) 2

  18. H2O(l)  H2(g) + O2(g) • H2O(l)  H2(g) + O2(g) 2 2

  19. Balancing Chemical Equations • Ca(s) + S8(s)  CaS(s) 8 • Ca(s) + S8(s)  CaS(s) 8

  20. Zn(s) + HCl(aq)  ZnCl2(aq) + H2(g) 2 • Zn(s) + HCl(aq)  ZnCl2(aq) + H2(g)

  21. Rules for balancing an equation 1. Only change the coefficients that appear in front of an element or compound 2. Never change any subscripts in a formula 3. Coefficients should be written as the lowest possible ratios 4. Begin by balancing elements that appear ONLY once on each side of the equation

  22. A: 1 Dec. 2010 Take Out Homework: Week 13 #9-12 Objective: SWBAT balance chemical equations and model the law of conservation of mass. Do now: Count the number of atoms of each element: 5Mg(NO3)2

  23. Agenda • Do now, homework solutions • More balancing equations • Paperclip bonding mini-lab • Mole ratios Homework: Finish Mini-Lab Handout: Thurs. Lab Report: Fri. Read “Mass and Mole Relationships” lab and do pre-lab (p. 2)

  24. C: 1 Dec. 2010 Take Out Homework: Week 13 #1-15 Objective: SWBAT balance chemical equations and model the law of conservation of mass. Do now: Count the number of atoms of each element: 5Mg(NO3)2

  25. Agenda • Do now, homework solutions • More balancing equations Homework: Week 13 Homework #16-23 Lab Report: Fri.

  26. Examples __CaCO3 + __HCl __CaCl2 + __CO2 + __H2O __H2S + __O2 __SO2 + __H2O __CaO + __HNO3 __Ca(NO3)2 + __H2O __Fe(OH)3 __Fe2O3 + __H2O

  27. Balancing Chemical Equations • __CaO + __HNO3 __Ca(NO3)2 + __H2O • __Fe(OH)3 __Fe2O3 + __H2O • __ZnS + __ O2 __ ZnO + __ SO2 • __ Ag3PO4 + __KBr __K3PO4 + __ AgBr • __ H2SO3 + __O2 __ H2SO4 • __Na2SO4 + __Fe(NO3)3__NaNO3 + __Fe2(SO4)3 • __ AgNO3 + __CaCl2__AgCl + __Ca(NO3)2

  28. Na2O2 + H2O NaOH + O2

  29. 2Na2O2 + 2H2O  4NaOH + O2

  30. KClO3KCl + KClO4

  31. 4KClO3KCl + 3KClO4

  32. CaCl2 + Fe2(SO4)3 CaSO4 + FeCl3

  33. 3CaCl2 + Fe2(SO4)3 3CaSO4 + 2FeCl3

  34. Al2O3 + HCl AlCl3 + H2O

  35. Al2O3 + 6HCl  2AlCl3 + 3H2O

  36. AgNO3 + CaCl2AgCl + Ca(NO3)2

  37. 2AgNO3 + CaCl2 2AgCl + Ca(NO3)2

  38. Na2SO4 + Fe(NO3)3 NaNO3 + Fe2(SO4)3

  39. 3Na2SO4 + 2Fe(NO3)3 6NaNO3 + Fe2(SO4)3

  40. 3Na2SO4 + 2Fe(NO3)3 6NaNO3 + Fe2(SO4)3

  41. C12H22O11 + O2 CO2 + H2O

  42. C12H22O11 + 12O2 12CO2 + 11H2O

  43. BaCl2 + (NH4)2CO3 BaCO3 + NH4Cl

  44. BaCl2 + (NH4)2CO3 BaCO3 + 2NH4Cl

  45. Liquid silicon tetrachloride reacts with liquid water to produce solid silicon dioxide and a solution of hydrochloric acid.

  46. SiCl4(l) + 2H2O(l)  SiO2(s) + 4HCl(aq)

  47. Nitrogen gas reacts with oxygen gas and water to produce a solution of hydrogen nitrate.

  48. 2N2(g) + 5O2(g) 2H2O(l)  4HNO3(aq)

  49. KOH + Cl2KCl + KClO3 + H2O

  50. 6KOH + 3Cl2 5KCl + KClO3 + 3H2O

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