1. Physical vs. Chemical Changes Notes

2. TEKS 6.5D identify the formation of a new substance by using the evidence of a possible chemical change such as production of a gas, change in temperature, production of a precipitate, or color change. TEKS 8.5E investigate how evidence of chemical reactions indicate that new substances with different properties are formed. 3. Matter undergoes changes all of the time. 4. There are two types of changes: chemicalchemical physicalphysical && 5. Physical changes: 6. Physical changes occur when the appearance of a substance changes 7. but chemicallychemically the substance is the same. 8. The individualThe individual molecules domolecules do notnot changechange.. 9. Examples ofExamples of physical changesphysical changes are, melting,are, melting, freezing,freezing, 10. or changingor changing sizesize oror shapeshape.. 11. A physicalA physical change alsochange also occursoccurs whenwhen substancessubstances areare 12. mixedmixed and somethingand something dissolvesdissolveslike makinglike making salt water or Kool-salt water or Kool- aid.aid. 13. The water, saltThe water, salt and sugar stilland sugar still keep theirkeep their originaloriginal propertiesproperties andand the substancesthe substances can be separatedcan be separated again.again. 14. ChemicalChemical ChangesChanges 15. AA chemicalchemical changechange occursoccurs when the atomswhen the atoms making up mattermaking up matter rearrangerearrange.... 16. to form a newto form a new substance withsubstance with new propertiesnew properties.. 17. This usuallyThis usually occurs during aoccurs during a chemicalchemical reactionreaction.. 18. Evidence ofEvidence of a chemicala chemical change:change: 19. ProductionProduction of a gas.of a gas. 20. bubblesbubbles fizzingfizzing foamingfoaming smokesmoke odorodor 21. color changecolor change *not all color*not all color changes arechanges are chemical!chemical! 22. AA differentdifferent color appearscolor appears 23. *not all color*not all color changes arechanges are chemical!chemical! 24. FormationFormation of aof a precipitateprecipitate 25. cloudinesscloudiness foggyfoggy solidsolid atat bottom ofbottom of containercontainer 26. Change inChange in heatheat or lightor light energyenergy 27. SparksSparks explosionexplosion glowingglowing 28. temperaturetemperature increases orincreases or decreasesdecreases 29. TheseThese are onlyare only cluesclues 30. a chemical changea chemical change has not actuallyhas not actually taken place unlesstaken place unless matter has changedmatter has changed into ainto a newnew substancesubstance.. 31. Some commonSome common examples ofexamples of chemicalchemical changeschanges includeinclude 32. RustingRusting 33. TarnishingTarnishing 34. BurningBurning 35. CookingCooking 36. DigestingDigesting 37. If you have theIf you have the chemicalchemical equationequation,, you can tell if ayou can tell if a chemical changechemical change has taken placehas taken place byby 38. Looking to seeLooking to see if the productsif the products in the equationin the equation are.are. 39. differentdifferent fromfrom thethe reactantsreactants..