Science chapter 5

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Across
  1. 3. energy-the minimum amount of energy required to start a chemical equation
  2. 5. to form a new substance
  3. 7. reaction-is any process with an increase in the enthalpy H of the system
  4. 8. change-changes affecting the form of a substance
  5. 9. when compounds break down into similar products
  6. 10. reaction-reaction for which the overall standard enthalpy change is negative
  7. 11. species formed from chemical reactions
  8. 12. amount of a substance in a given volume
  9. 15. system-A closed system is a physical system that does not allow transfer of matter in or out of the system
  10. 16. a number placed in front of a chemical formula in an equation
  11. 18. when 2 or more elements or compounds combine to make a more complex substance
  12. 19. substance to be deposited in solid form from a solution
  13. 20. of conservation of mass-the mass of the system must remain constant over time
Down
  1. 1. substance that takes part in and undergoes change during a reaction
  2. 2. catalysts that help reactions occur at body temperature
  3. 4. equation-the symbolic representation of a chemical reaction in the form of symbols and formulae
  4. 6. one element replaces another in a compound or if 2 elements in different compounds trade places
  5. 13. change-occurs when a substance combines with
  6. 14. system-a material system in which mass or energy can be lost to or gained from the environment
  7. 15. increases-the reaction rate by lowering the activation energy needed
  8. 17. material used to decrease the rate of a chemical reaction