Physical Changes and Chemical Changes, Exams of Chemistry

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Physical ChangesPhysical ChangesPhysical ChangesPhysical Changes

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Chemical ChangesChemical ChangesChemical ChangesChemical Changes

Physical ChangesPhysical ChangesPhysical ChangesPhysical Changes A physical change is when a substancechanges, but remains the same substance.
Change in size.  If a piece of paper is cut into two pieces, the paper becomessmaller, but still remains as paper.
Change in shape.  A tree is carved into a baseball bat. The wood changes shape,but still remains as wood.
Change in state.  HO as liquid water freezes and changes into solid ice. The H^2

O 2

changes state from a liquid to a solid, but still remains H

O. 2

More about changes of state…change from onestate of matter to another.
^ Liquid to Solid / Solid to Liquid^ ^ If something changes from a liquid to a solid it is called freezing.^ ○^ Substances do not have to be “cold” to freeze. Most metals willchange from liquid metal to solid metal at room temperature.^ ^ If something changes from a solid to a liquid it is called melting.^ ○^ Substances do not have to be “hot” to melt. Ice will melt at roomtemperature.
^ Liquid to Gas / Gas to Liquid^ ^ If something changes from a liquid to a gas it is calledvaporization.^ ○^ After a rain, the liquid water (H

O) on the ground eventually 2 disappears. The water changes from a liquid to H

O gas in the air. 2

^ If something changes from a gas to a liquid to a gas it is calledcondensation.^ ○^ Clouds are a result of H

O changing from a gas to a liquid. 2

Chemical ChangesChemical ChangesChemical ChangesChemical Changes A chemical change is when a substancechanges into a new substance.
Change into a new substance.  When a chemical change occurs, a new substance forms that hascompletely different properties than the original substance.^ ○^ Paper is a white solid. When paper is burned, it is turned into ashwhich is a black, flaky substance. Ash has completely differentproperties than paper.^ ○^ When sodium, a slivery colored soft metal is combined with chlorine, agreen poisonous gas, it forms table salt!  When a chemical change occurs it is very difficult if notimpossible to return the substance to its original form.^ ○^ Once paper has burned and turned into ash, it is impossible to turn itback into paper!

Is this a Physical orIs this a Physical orIs this a Physical orIs this a Physical orChemical change?Chemical change?Chemical change?Chemical change?Bread Toasting…..This is a Chemical Change!Butter melting on your toast…..This is a Physical Change!

Is this a Physical orIs this a Physical orIs this a Physical orIs this a Physical orChemical change?Chemical change?Chemical change?Chemical change?Getting a haircut…..This is a Physical Change!Ice Cubes Melting…..This is a Physical Change too!