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Physical or Chemical change?
sodium hydroxide dissolves in water?
hydrochlorlc acid reacts with sodium hydroxide to produce a salt,water, and heat?
a pellet of sodium is sliced in two?
water is heated and changes to steam?
wood rots?
potassium chlorate decomposes to potassium chloride and oxygen gas?
acid on limestone produces carbon dioxide gas?
cooking?
2 Answers
- Anonymous1 decade agoFavorite Answer
A physical change is one where the chemicals remain the same, just get mixed together.
A chemical change is a reaction of some kind where you get different chemicals.
sodium hydroxide dissolving in water is CHEMICAL because this is the reaction:
NaOH + H2O >> Na+ + H20 + OH- now you have separate ions, Na & OH in the H2O.
Same with #2.
HCl + NaOH >> H20 + NaCl (the heat is given off by the chemicals reacting - this is an EXOTHERMIC reaction)
A pellet of Na sliced in 2? Don't you still have a pellet of Na, just 2 1/2s?
Water changes state, from liquid to steam, but it is STILL H2O.
Wood rots, turning into something else.
2KClO3 >> 2KCl + 3O2
acid on limestone is dissolving it, the CO2 is a PRODUCT of the reaction. If it's a chem reaction, it's a _______ change?
Cooking can be either physical or chemical - think about it.
If you burn chicken, it gets a carbon (charcoal) skin as the carbon in the proteins are burned. It can be physical as well - cooking rice is adding rice to hot H20. In the end, the rice absorbs the H20, but it is still RICE. I guess you could call that a chem change because now it's rice with h20 in its cells... Salad is a physical change. You cut everything up and mix it together. The lettuce is still lettuce. However, if you add the cooked chicken, even though you burned the chicken - it's STILL chicken, and just mixed with the rest of the salad!
Hope this helps!
- wehrlyLv 44 years ago
CHEMICAL. actual is what you do to a bite of paper once you rip it aside. You my have replaced its visual charm, yet you haven't any longer replaced the certainty that it somewhat is paper, its identification. Its chemical composition has no longer replaced. usually this is something like bending, breaking, cracking, splitting, etc. Chemical is once you modify the molecular shape or something. Baking is a chemical reaction, have faith it or no longer. the place do you think of the air wallet in bread come from? gasoline released because of the fact of a chemical reaction. plus the cake is popping from liquid to stable.
