Physical and chemical changes happen all the time in the world. The labs which were done last week revolved around similar concepts. Basically, the ideas of physical changes and chemical changes were experienced and fully understood through the exposure to these labs. Since the class was learning about states of matter and the correlations between them, these concepts really helped us understand how matter is altered through specific changes.
To start off with, a physical change is a change of the appearance of a substance, where the identity of the substance does not change. On the other hand, a chemical change is the result of a substance being changed into one or more new substances.
In a similar lab, a lighted candle was met with carbon dioxide. The carbon dioxide was composed of the mixture of baking soda and vinegar. Carbon dioxide is a gas. Gas is a phase of matter that does not have a definite shape or volume. The flame of the candle blew out because the presence of the carbon dioxide caused the fire to have no oxygen. This was evident as a chemical change because the fire substance was altered and in fact, it vanished. The knowledge of carbon dioxide can be used in daily life situtations. In the future, if you have problems with fires, you can always put them out by exposing them to carbon dioxide.
In the third lab, we roasted marshmallows for our amusement. In the process of roasting marshmallows, the class discovered a chemical change. Marshmallows were held above a bunsen burner and soon the marshmallow started to burn. The white and solid substance of the marshmallow turned into a burnt and gooey substance. The marshmallow was gooey because it was near a hot fire and its composition melted in some ways. Most importantly, the marshmallow was burnt and the process of combustion is known to be a chemical change. In this lab, the chemical makeup of the marshmallow changed drastically. For another part of this lab, a physical change was identified. The original marshmallow was split into half but no chemical makeup was changed. As a matter of fact, only the appearance of the marshmallow changed. By the way, the marshmallow was known to be a solid only because it had a definite shape and definite volume. The particles inside the marshmallow were closely packed together which made it a solid.
In another lab, the purpose was to burn sugar and identify changes. When the sugar substance was heated on the bunsen burner, the white of the sugar became a burnt and black color. Combustion was evident and I immediately knew that it was a chemical change. The original composition of the sugar was changed into a burnt mixture. The burnt mixture had a bit of yellow in it too. Also, since water was combined with sugar when the substance was heated, the water evaporated. Basically, a liquid turned into a gas. In other words, the water changed into water vapor. A liquid is a state of matter which is known to have a definite volume, but no definite shape. Knowledge of evaporation can help people understand how water vapor forms in the future.
Therefore, in all four labs, physical changes and chemical changes were experienced. Some changes included melting, combustion, and evaporation. Also, the key points of these labs can be helpful in understanding situations in the future. For instance, the melting of a substance is a major physical change. When you are cutting a birthday cake in the future, you should make sure to blow out your candle soon enough so it doesn't melt into your cake. Also, combustion definitely changes the chemical make up of an object. Burning has to do with fire and when fire encounters an object it is likely to burn the object. The fire will also create a chemical build up, changing the object's composition. In daily life, you should be aware that fire could change the internal and external make up of anything it catches onto. For example, when you are making a campfire, fire burns the wood. The chemical change is that the wood could turn to ash. A final example of a change in matter is with an ice cube. In the future, an ice cube could physically change to water through the process of melting.
Some citations:
http://scienceprojectideasforkids.com/2009/states-of-matterenthalpy/
http://boomeria.org/chemtextbook/cch15.html
http://www.clker.com/clipart-10942.html
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