From the two candle labs we conducted in class, much information was learned. In the first lab, there was an example of physical and chemical properties and changes and it helped us better understand them. By observing an unlit candle, it was easy to describe physical properties such as looks or appearance. Since the candle was still unlit, there were no chemical properties seen. After the candle was lit, immediate changes were easily noticed, both physically and chemically. Since these were noticed after adding fire to the candle, these were classified as physical and chemical changes. Common changes described were things such as the candle melting, the wick turning black, smoke being produced, and the candle burning. It was also realized that in order to observe a chemical property of the candle, it must be lit on fire. This lab helped distinguish physical and chemical properties and the difference between a physical and chemical change. By taking a small birthday candle and adding a flame to it, students were able to clearly see and understand the simple scientific concept of classifying physical and chemical properties and changes. Skills learned were to be able to tell physical and chemical properties apart, keeping in mind their definitions. This lab helps people in real life because when things are occurring in the world around them, like water evaporating, baking a cake, or rust forming on metal, they will be able to classify them and better understand what certain things caused this reaction to take place. Below, see the comparison between before and after the flame was lit.
In the second lab, carbon dioxide being able to put out a flame was being observed. In this lab, a candle was lit on fire and was able to burn. By mixing baking soda with vinegar, carbon dioxide was formed (shown below). This is an example of a chemical change, because a new substance was formed.
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| Baking soda and vinegar form carbon dioxide when mixed |
After following lab instructions, it was learned that tipping carbon dioxide gas over a flame would cause the flame to extinguish. It was concluded that this was because carbon dioxide smothers the oxygen from the candle, so the flame is unable to burn. Carbon dioxide does this because it is heavier than air. This lab taught us the skills to observe details closely, measure precisely, and be extremely careful to follow lab instructions. It showed us chemical changes that occurred. This can be applied to real life because it is known that carbon dioxide is heavier than air, so carbon dioxide could be used to put out grease and electrical fires, which cannot be contained with just water. The carbon dioxide would blanket the fire. It could also be used in making carbonated soft drinks, which use carbonated water to cause fizz. Carbon dioxide could also be used in the form of dry ice, to cause fog in movies, or used to chill perishable foods during transport.
