why is popping popcorn a chemical and physcial change?
i need reasoning, not just an agreement.
- 1 decade agoFavorite Answer
First of all, everything that happens around us is either a chemical or physical change, or sometimes both. In the case of popcorn, you can easily see that a change has happened because the inital product is different from the final product. Also, the popcorn you initially see is different from the popcorn that you eat. It tastes better, too.
Chemical changes in popcorn include the alteration of its chemical contents, for example, the starch contained in the corn now is converted to a more digestible form. It's pretty much the same when you fry an egg: when you break it, the white yolk is transparent, but when it's fried, the white becomes, well, white... and more edible if compared to its previous state.
Physical change is the easiest to observe; it can be seen from the obvious, for example increase in size and colour. Also, it's hot to touch, unlike before you pop it.
Hope that helps!
- 1 decade ago
As with all cereal grains, each kernel of popcorn contains a certain amount of moisture in its starchy endosperm. Unlike most other grains, the outer hull, or pericarp, of the popcorn kernel is thick and impervious to moisture.
As the kernel is heated past the boiling point, water in the kernel begins to turn to steam, generating an internal pressure of about 9 atm. In kernels of other grains (and in damaged kernels of popcorn), this steam escapes as fast as it forms, but in the tightly sealed popcorn kernel, the steam is held tight by the pericarp and the pressure starts to build until the pericarp suddenly ruptures, causing a small explosion. The force of the explosion turns the kernel inside out. More importantly, because the moisture is evenly distributed throughout the starchy endosperm, the sudden expansion turns the endosperm into an airy foam which gives popcorn its unique texture.
Two explanations exist for kernels which do not pop, known in the popcorn industry as "old maids," after being exposed to high temperatures. The first is that unpopped kernels do not have enough moisture to create enough steam for an explosion. The second explanation, according to research led by Dr. Bruce Hamaker of Purdue University, is that the unpopped kernel may have a leaky hull.
- Anonymous5 years ago
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The act of popcorn popping is a physical rather than chemical change. Air within the popcorn seed is heated, causing it to build up to higher pressure than the air outside. As a result of this, the air is explosively released to the area of lower pressure, in effect popping the popcorn.
- Anonymous1 decade ago
physical-- the look of it has changed; once a small kernel, now a piece of popcorn
chemical-- the atoms in it have rearranged, making it a chemical reaction
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- 1 decade ago
PHYSICAL, CAUSE THE FORM CHANGES, CHEMICAL, CAUSE HEAT ALTERS THE CHEMICAL MAKE UP
- 1 decade ago