dissolving salt.. physical or chemical change?

Question

my chemistry teacher said its a chemical change, but i cant find an online source that can tell me why... can someone please help me?

Answer 1

chemical, it melted in the water, so it is no longer salt

Answer 2

Assuming that you dissolve the salt in water: physical change. If you dissolve the salt in, say, vinegar, then it'll be a chemical change because the chlorine from the salt (NaCl) will combine with some hydrogen in the acetic acid (don't remember the formula) and you'll end up with some weak hydrochloric acid (HCl) -- the salt will have been changed chemically, not physically. Water does not have the necessary electronic properties to dissociate the sodium (Na) and the chlorine (Cl) the way acetic acid (vinegar) does.

Do this experiment to prove that dissolving salt in water is a physical change: get a glass dish and weigh it, then add a little salt and weigh again. Put enough water in to dissolve the salt and weigh once more. Do the math and you'll have the mass (weight) of the dish, the salt, and the water, individually. Stir it around to dissolve the salt. Wait until the water evaporates (the next day?) and the salt will remain in the dish as a white residue. The salt won't be cute little cubes like before you dissolved them, but it certainly is not a chemical change. Assuming that no additional mass got into the dish while you were waiting for the water to evaporate (actually, a negligible amount of solids were dissolved in the water before you started the experiment but they shouldn't affect the results), the weight of the dish will now be equivalent to the dish plus the salt because only the water will have evaporated, not any of the salt (it's why the oceans are salty. . . the water evaporates while the salt stays behind). If you're a girl, pick some residue up on the tip of your finger and taste it (it will taste like salt, proving that it has not changed chemically, only physically). If you're a guy, simply pick up the dish and lick it (it will still taste like salt for the same reason).

Answer 3

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It is chemical reaction. you are going from a balanced charged compound to two compounds with charge. If it was a physical change you would never have ppt from solutions. eg add Ba(NO3)2 + CuSO4 you get a ppt of BaSO4 this is not the same compound therefore the compound must dissasociate for this to happen. Need I go further into the chemistry of salts in water in the transistion metal range? Every time salt dissolves in water heat is needed (or released). Now a reaction can be exothermic (burn you) or endothermic (freeze you). Of course a physical change will do this. BUT they will not do it if both compounds are at the same temperature. So, therefore, dissolving salt in water is a chemical reaction. I need to qualify this a bit more. It is a reversible chemical reaction. eg. BaCl2(s) + 6H2O(l) <===> [Ba(H2O)6]2+(aq) + 2Cl-(aq) There is a whole branch of science devoted to this>

Answer 4

A physical change in which a substance changes states between solid, liquid and gas is called a phase change.

Also, the reaction is reversable, a charecteristic of a physical change. Table salt is simly NaCl, and will remain that way even when dissolved in water.

Answer 5

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RE:
dissolving salt.. physical or chemical change?
my chemistry teacher said its a chemical change, but i cant find an online source that can tell me why... can someone please help me?

Answer 6

Ok, all these people are plain stupid. Dont answer a damn question if you dont know the answer.

Its a physical change. Why? Because the salt doesnt change to something else, it stays salt. Boil the water and the salt will still be there, not something else.

Answer 7

probably gonna get hate for my answer, but CHEMICAL because the salt is being being turned from a solid into its aqueous state, thus the salt is separated and the different atoms are dissociating to their negative or positive ions

Answer 8

your chem teacher is totally wrong... its a physical change because you can get the salt back by heating the solution. moreover the bonding of the water and salt does not change to make a whole new substance

Answer 9

its a phyisical change....your teachers is wrong =_=

dissolving salt does not change the arrangement of atoms...

if you can recover the salt (which you can) through...say..like distillation...then its physical...

chemical changes are permanent...you cant recover your original reactant

Answer 10

you are only diluting it. then, if you heat the solution,...you will have salt again!.

the NaCl separates itself into ions..Na+ ions and Cl- ions..and these are surrounded by polar water molecules through hydrogen bonding (blah blah...I better don't confuse you) and maybe that is why your teacher said it was a chemical change.

Answer 11

that's Physical