Chemical reactions


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Chemical reactions

  1. 1. Chemical Reactions Use Models to represent chemical reactions. Describe chemical reactions using equations. Investigate chemical and physical change.
  2. 2. Next Tuesday-Lab <ul><li>If you could bring in one bottle of Elmer’s glue, we will be able to do the lab on Tuesday!!! Thanks. </li></ul><ul><li>I need it by Monday! </li></ul>
  3. 3. Chemical Reactions <ul><li>Vocabulary </li></ul><ul><li>Reactant-participate in the reaction </li></ul><ul><li>Product-what is produced by the reaction </li></ul><ul><li>Exothermic-Release energy </li></ul><ul><li>Endothermic-Absorb energy </li></ul>
  4. 4. Brain Storm <ul><li>With a partner-take 1 minute to make a list of chemical reactions that you witness or do every day. </li></ul>
  5. 5. <ul><li>Chemical reactions Rearrange atoms </li></ul>
  6. 6. Synthesis-combines substances <ul><li>A + B AB </li></ul><ul><li>2Na + Cl 2 2NaCl </li></ul><ul><li>You start with two separate substances and they combine to make something new. </li></ul>
  7. 7. Decomposition <ul><li>AB A + B </li></ul><ul><li>2H 2 O 2H 2 + O 2 </li></ul><ul><li>Start with one substance and break it down into two. </li></ul>
  8. 8. Single Replacement Reaction <ul><li>AX + B AB + X </li></ul><ul><li>The “Scandalous” element steals away the Compounds partner and replaces it with itself . </li></ul>
  9. 9. Combustion Reaction <ul><li>Use oxygen as a reactant </li></ul><ul><li>CH 4 + 2O 2 CO 2 + 2H 2 0 </li></ul>
  10. 10. Double Replacement Reaction <ul><li>AX + BY AY + BX </li></ul><ul><li>A reaction where two compounds appear to exchange ions </li></ul>
  11. 13. <ul><li>Chemical Rxns (reactions) rearrange the atoms in an equation </li></ul><ul><li>Occur when substances go through chemical changes to form new substances. </li></ul><ul><li>Add energy to break bonds </li></ul><ul><li>Release energy to form bonds </li></ul>
  12. 14. <ul><li>____ Ag 2 SO 4 + ____ NaNO 3  </li></ul><ul><li>____ NaI + ____ CaSO 4  </li></ul><ul><li>____ HNO 3 + ____ Ca(OH) 2  </li></ul><ul><li>____ CaCO 3  </li></ul><ul><li>____ AlCl 3 + ____ (NH 4 )PO 4  </li></ul><ul><li>6) ____ Pb + ____ Fe(NO 3 ) 3  </li></ul>
  13. 15. Signs of a chemical reaction <ul><li>Changes you can see </li></ul><ul><ul><li>Formation of a gas, </li></ul></ul><ul><ul><li>Formation of a solid </li></ul></ul><ul><ul><li>Color Changes </li></ul></ul><ul><ul><li>Release of energy (heat/energy) </li></ul></ul>
  14. 16. Law of Conservation of Mass/Energy <ul><li>Energy is Conserved </li></ul><ul><li>The energy you start with is the same energy that you end with just in a different form. </li></ul><ul><li>Total amount of energy of reactants must always equal the total amount of energy in the products and their surrounding environment. </li></ul>
  15. 17. <ul><li>Reactions that release energy are exothermic </li></ul><ul><li>Reactions that absorb energy are endothermic </li></ul>
  16. 18. Energy and Reactions <ul><li>Reactions that release energy are exothermic- </li></ul><ul><li>Examples-combustion reactions are always exothermic </li></ul><ul><li>Products have less energy than the reactants. </li></ul>
  17. 20. Reaction Rates <ul><li>Anything that increases contact between particles will increase the rate of reaction. </li></ul>
  18. 21. <ul><li>Most reactions go faster at higher temperatures </li></ul><ul><li>Large surface area </li></ul><ul><li>Higher concentrations of reactants react faster </li></ul>
  19. 22. <ul><li>Higher pressure increases reaction rate </li></ul><ul><li>Catalysts speed up reactions </li></ul><ul><li>Enzymes are biological catalysts </li></ul>
  20. 23. Balancing Equations <ul><li>1. Get yourself an unbalanced equation .  I might give this to you, or I might make you figure it out. </li></ul><ul><li>2. Draw boxes around all the chemical formulas.   Never, ever, change anything inside the boxes . Ever. Really. If you do, you're  guaranteed  to get the answer wrong. </li></ul>
  21. 24. <ul><li>3. Make an element inventory .  How are you going to know if the equation is balanced if you don't actually make a list of how many of each atom you have?  </li></ul><ul><li>4 . Write numbers in front of each of the boxes until the inventory for each element is the same both before and after the reaction.  Whenever you change a number, make sure to update the inventory - otherwise, you run the risk of balancing it incorrectly. When all the numbers in the inventory balance, then the equation can balance. </li></ul>
  22. 25. <ul><li>Example </li></ul><ul><li>1. __NaCl + __BeF 2  --> __NaF + __BeCl 2 </li></ul><ul><li>2. __FeCl 3  + __Be 3 (PO 4 ) 2  --> __BeCl 2  + __FePO 4 </li></ul><ul><li>3. __AgNO 3  + __LiOH --> __AgOH + __LiNO 3 </li></ul><ul><li>4. __CH 4  + __O 2  --> __CO 2  + __H 2 O </li></ul><ul><li>5. __Mg + __Mn 2 O 3  --> __MgO + __Mn </li></ul>
  23. 26. <ul><li>Bill Nye </li></ul>
  24. 27. Exit Ticket <ul><li>Predict what products will be found in </li></ul><ul><li>The decomposition of HgO </li></ul><ul><li>Calcium Carbonate and Hydrochloric Acid (HCL) reacting together. </li></ul>
  25. 28. Exit ticket <ul><li>List 3 signs that could indicate that a chemical reaction is taking place. </li></ul>