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PART 1 : Introduction to Chemical Reactions 9a

PART 1 : Introduction to Chemical Reactions 9a. In a chemical reaction…. atoms are ____________ (fill in the blank). What are some common reactions in your everyday life?. How can you tell when a chemical reaction has taken place ?.

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PART 1 : Introduction to Chemical Reactions 9a

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  1. PART 1:Introduction to Chemical Reactions9a

  2. In a chemical reaction… atoms are ____________ (fill in the blank)

  3. What are some common reactions in your everyday life?

  4. How can you tell when a chemical reaction has taken place?

  5. Formation of a ___________________also known as a ___________________

  6. HOW DO CHEMISTS REPRESENT CHEMICAL REACTIONS?

  7. Chemists use ______________ to represent chemical reactions. The starting substances are __________________What youend up with are _____________When do you use chemical equations in your own life?

  8. REAL LIFE EXAMPLE: You are going to bake cookies. You know that: ____flour + ____sugar + ____baking powder + ___butter + ___chocolate chips makes ___cookies This is a _______________EQUATION. What are the product(s)? What are the reactant(s)?

  9. What else do you need to know…. if you already know that you need to bake them at 350 for ½ hour??

  10. You need to know the _________________ ______________________ of the ingredients with respect to each other.In other words, you need a ___________________ ________________(Remember – cooking is chemistry!!)

  11. HOW MIGHT A CHEMIST USE A CHEMICAL EQUATION?

  12. You are an EVIRONMENTAL CHEMIST concerned about GLOBAL WARMING You are asked to determine how much carbon dioxide will be produced from the amount of methane burned by a factory. The first thing you need is a WORD EQUATION

  13. methane + oxygen yields carbon dioxide + water

  14. Word equations are clunky and they don’t tell you very much… You can make your equation less clunky if you use _________________________instead of words.

  15. __ CH4 + __O2 __CO2 + __ H2O This type of equation is a ____________ equation.

  16. In addition, to give more information in an equation, symbols are used to represent the _____________________ of the substances, including:Solids = _______ Aqueous = ______Gases = _______ Liquids = ______(Aqueous means ___________________________________________________

  17. __ CH4(g) + __ O2(g) __ CO2(g) +__ H2O(l)This equation still doesn’t have enough information…What else do you need?

  18. What law allows us to balance equations? State this law.

  19. CH4 CO2 O2 H2O

  20. A very important rule in balancing equations: never change the________________________ For example:______ cannot be changed to _______

  21. PART 2BALANCINGEQUATIONS The Skill

  22. The Law of Conservation of Mass says…You must have the same number of atoms of a particular element on both sides of a chemical equation…i.e., the equation must be BALANCED!

  23. There are 2 different types of numbers in chemical equations.COEFFICIENTS__ CH4 + 2 O2 __CO2 + 2 H2O SUBSCRIPTSSubscripts cannot be changed while balancing an equation…remember CO vs CO2?

  24. However,COEFFICIENTScan be changed in order to balance an equation.Begin by counting the number of atoms of each element… ___ Na(s) + ___ Cl2(g) ___ NaCl(s)

  25. ___H2(g) +___ N2(g) ___ NH3(g)

  26. __ Al2O3(s) ___ Al(s)+ ___O2(g)

  27. ___ Fe(BrO3)3 → ___ FeBr3 + ___ O2

  28. ANOTHER RULE: If you balance an equation, and then find that all of the coefficients are divisible by a common number, you must divide them by that number…

  29. 2CH4 + 4O22CO2+4H2O WRONG!

  30. CH4 + 2O2CO2+2H2O RIGHT!!

  31. Hint #1If a polyatomic ion appears unchanged on both sides of the equation, balance it as a UNIT – not as individual atoms

  32. __Al(NO3)3 + __LiOH __LiNO3 + __ Al(OH)3

  33. ] [ [ ] [ ] [ ] [ ] [ ] Al(OH)3 Al(NO3)3 [ ] [ ] LiOH LiNO3

  34. __(NH4)3PO4 +__ BaSO4 __(NH4)2SO4 +__Ba3(PO4)2

  35. Example of an acid-base reaction.__ H2SO4 + __KOH ___K2SO4 + __ H2O

  36. Hint #2 First, balance an element that only appears in one reactant and one product (leaving oxygen to last and hydrogen to second last.)

  37. __C3H8+__O2 __CO2 + __H2O

  38. __C5H12 (g)+__O2(g) __CO2(g) + __H2O(l)

  39. HINT #3If you balance all of the elements and the polyatomic ions, except for one element, and there’s an odd # of that last element on one side, and an even number on the other side – balance that element with a fractional number (containing ½) and then double all of the coefficients

  40. __C5H10 + __O2 __CO2 + __H2O

  41. __C6H14 + __O2 __CO2 + __H2O

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