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Physical changes are the changes in which the original substance hasn't been chemically altered. Physical changes pertain to changes of energy and states of matter; the substance has only changed form. [1] This change does not produce a new substance; it merely changes the distance between particles.
Physical Properties
Physical properties are observations made with the senses and observations that can be made without changing the object/substance.
Changes of State
Changes of state whether it be melting, freezing, vaporizing, or condensing doesn't alter the chemical composition of a substance. Physical changes can be reversed, like freezing a liquid to become a solid and then it returns to a liquid state when the heat is added [2].
- When you freeze water, you get a solid called ice. When you melt the ice, you get water, a liquid. When you boil the water, you get water vapor, which is a gas. When you boil water (H2O), the process produces steam, which is still the molecules of water (H2O) but in a different form [3].
- When water freezes, the water (H2O) becomes a solid, but it is still water (H2O).Throughout this whole time, the substance kept it's "fundamental components" of hydrogen and oxygen, with common name H20 [3].
In solids, the water molecules are locked into rigid positions and close together. [3] In liquids, the water molecules are still close together but can move around to some extent [3]. In gases, the water moecules are far apart and move randomly. [3]
This type of change is one in which "chemical bonds are not broken" [4]. To put it in a different way, a physical change involves the modification "in the form of a substance" [3]. There is "no change in the fundamental components that make up a substance." [3]
Other examples of physical changes are smashing a rock into tiny pieces, melting wax, carving wood, and deflating a balloon.
Differences Between Physical and Chemical Changes
In a chemical change, the atoms of individual molecules get rearranged, chemical bonds are made and/or broken [5]. In a physical change, the molecules remain intact while other properties change [6]. Physical changes will only allow the same chemical compound to take one of the four states of matter (solid, liquid, gas and plasma). Chemical changes will allow the chemical compound to rearrange its molecular structure into a different compound that also may exist at any of the four physical states of matter [7]. There are really only two criteria for whether a change is chemical or physical: 1) After the change does it look the same and 2) can you change it back? If the answer is yes, the change is physical every time [8]. If the answer is no the change is chemical every time.
See Also
The other kind of change within a substance is called a chemical change. A chemical change is also referred to as a chemical reaction. Chemical reactions create a new substance that has new physical and chemical properties compared to its original form [9]. At a molecular level, a physical change involves rearrangements at the substance's particles, meanwhile, a chemical change is the forming of a new substance as it's particles are broken apart and then rearranged into new particles [10]. Some examples of chemical changes are lighting a match, digesting food in our stomachs, or leaves turning different colors in the fall [11]. Reversing objects back into its original form after a chemical change has occurred is not an easy task. For example, its not difficult to change the state of water; heating or cooling it. When frying an egg, it is impossible to change it back to its original form. You can't unfry an egg.
References
- ↑ Westbroek, Glen. "Physical Change". January 28, 2009 http://www.usoe.k12.ut.us/curr/science/sciber00/8th/matter/sciber/change.htm
- ↑ Rivera, Dan (2005). "Chemical Changes". Retrieved February 5, 2009, from http://www.ric.edu/faculty/ptiskus/chemical/
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Zumdahl, S.S., Zumdahl, S. L., DeCoste, D. J. (2006). World of Chemistry. Houghton Mifflin Company.
- ↑ Monroe County Women's Disability Network. (n.d.) Physical and Chemical Changes. Retrieved January 14, 2009, from http://www.mcwdn.org/chemist/pcchange.html
- ↑ Leon, Nelson De (2002). "Physical and Chemical Properties". Retrieved February 5, 2009, from http://www.iun.edu/~cpanhd/C101webnotes/matter-and-energy/properties.html
- ↑ Leon, Nelson De (2002). "Physical and Chemical Properties". Retrieved February 5, 2009, from http://www.iun.edu/~cpanhd/C101webnotes/matter-and-energy/properties.html
- ↑ Radar, Andrew (2007). "Chem4Kids". February 5, 2009, from http://www.chem4kids.com/files/matter_intro.html
- ↑ Smith, George (2009). "Physlink.com". Retrieved February 5, 2009, from http://www.physlink.com/Education/AskExperts/ae244.cfm
- ↑ The Annenberg Foundation (2009). "Physical Science". Retrieved February 5, 2009, from http://www.ric.edu/faculty/ptiskus/chemical/
- ↑ The Annenberg Foundation (2009). "Physical Science". Retrieved February 5, 2009, from http://www.ric.edu/faculty/ptiskus/chemical/
- ↑ The Annenberg Foundation (2009). "Physical Science". Retrieved February 5, 2009, from http://www.ric.edu/faculty/ptiskus/chemical/
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