chapter 19 chemical reactions

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Across
  1. 2. a chemical reaction in which one substance breaks down, or decomposes, into two or more substances.
  2. 6. a reaction in which the energy released is in the form of heat (thermal energy).
  3. 11. a change in which one or more substances are converted into new substances while energy is released or absorbed. Ex: combustion, growth, corrosion
  4. 12. an insoluble compound that comes out of solution during a double-displacement reaction.
  5. 13. number that represents the number of units of each chemical taking part in a reaction. Ex: 4NaCl (4 is the coefficient, meaning 4 units of NaCl)
  6. 15. the new chemicals present after a reaction. Ex: ashes + smoke
  7. 18. the chemicals present before a reaction. Ex: firewood + O2
Down
  1. 1. a chemical reaction in which the positive ion of one compound replaces the positive ion of the other to form two new compounds. Ex: precipitate formation (aka double-replacement)
  2. 3. a chemical reaction in which one element replaces another element in a compound. (aka single-replacement reaction)
  3. 4. a reaction that occurs when a substance (fuel) reacts with oxygen to release energy in the form of heat and light. Ex: fire wood burning, explosions
  4. 5. a way to describe a chemical reaction using chemical formulas and other symbols. Ex: Na + Cl  NaCl
  5. 7. a chemical reaction that absorbs energy primarily in the form of heat. SEE p.596
  6. 8. representation of what elements a compound contains and the exact number of the atoms of each element in a unit of that compound. Ex: H2O
  7. 9. a chemical reaction in which two or more substances combine to form another substance. Ex: photosynthesis; a metal combines with O2 to form rust
  8. 10. substance that is used to slow down a chemical reaction. Ex: Food preservative; paint preventing corrosion
  9. 14. a substance is dissolved in water
  10. 16. means ‘written below’; written after a chemical symbol to tell how many atoms of that element are in a unit of that compound.
  11. 17. substance that speeds up a chemical reaction without being permanently changed itself. SEE p.601 Ex: enzymes in saliva