Unit 5 Part 1 - Chemical Change

  • 3,647 views
Uploaded on

 

More in: Technology , Business
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
  • I liked the presentation, is worth every second spent
    watching it.
    http://www.debtsettlementideas.com
    http://www.debtsettlementideas.com/category/credit-repair
    http://www.debtsettlementideas.com/category/compare-credit-cards
    Are you sure you want to
    Your message goes here
    Be the first to like this
No Downloads

Views

Total Views
3,647
On Slideshare
0
From Embeds
0
Number of Embeds
0

Actions

Shares
Downloads
114
Comments
1
Likes
0

Embeds 0

No embeds

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
    No notes for slide

Transcript

  • 1. Chemical Reactions
  • 2. Part 1 Chemistry and Change…
  • 3. Review
    • Chemists classify the changes that they observe in substance into two broad categories:
      • Physical
      • Chemical
    • When water as a liquid changes to steam, is there a Chemical change?
  • 4. Is there a chemical change here?
    • Can you reverse the change made to the tomato? Chemical Reaction A chemical change is also known as a chemical reaction
    • Chemical reaction – is a process by which one or more substances undergo chemical changes into one or more different substances
      • “ Process” – this means it takes time.
      • “ one or more substances”
      • “ new” – different from what you started with.
  • 5. Law of Conservation of Mass
    • Law of Conservation of Mass “Mass is neither created nor destroyed during a chemical reaction”
      • I.e. If you started with 10kg of substances at the beginning of the reaction, you will end with 10kg of new substances at the end.
    • A toms rarely, if ever, change into other elements during most chemical changes. Therefore the atoms of each element we started with will be present at the end of the reaction.
  • 6.
    • Ex: Two H 2 molecules and one O 2 make 2 water molecules.
  • 7. Chemical Equations
    • Chemical Equations are how chemists represent a chemical reaction.
    • Chemical Equations: Indicate the substances “reacting” (changing) during the reaction.
      • Indicate chemicals which affect the time for the reaction to occur (catalysts).
      • Indicate the new substances formed following the reaction.
  • 8. Writing Chemical Equations
    • There are three ways to indicate chemical reactions. 1. Word Equation 2. Skeleton Equation 3. Balanced Chemical Equation (Preferred)
  • 9. Things you will find in a chemical equation.
    • Reactant(s) – the starting substances.
    • Product(s) – the new substances formed by the reaction.
    • Values – indicating the amount of substances (like a recipe). Symbols, to divide the reactants from the products and tell chemists the state of substances
  • 10. Word Equations
    • The least descriptive way to explain a chemical reaction. Iron(s) + Chlorine(g)  iron (III) chloride In sentence form it reads: “solid iron when combined with gaseous chlorine produces iron (III) chloride.”
  • 11. Writing Word Equations
    • Write a word equation for the following chemical reactions:
      • Water under electrolysis produces hydrogen gas and oxygen gas.
      • Solid Sodium and chlorine gas will combine to yield sodium chloride.
    • Word equations are too long to write and do not give enough information about the substances in the reaction. Typically they are not used.
  • 12. Skeleton Equations
    • Instead of writing words, skeleton equations use chemical formulas.
    • Writing a Skeleton Equations
      • Write skeleton equations for the two examples above.
      • Note: remember diatomic molecules?
    • Skeleton equations are an improvement over word equations, but do not satisfy the law of conservation of mass.
  • 13. Balanced Chemical Equations
      • Similar to skeleton equations, but satisfy the Law of Conservation of Mass.
    • Balancing a Chemical Equation
  • 14.  
  • 15. Write Balanced Chemical equations for the skeleton equations above: