Out of a candle burning, salt dissolving in water, vinegar and baking soda producing bubbles, adding hydrochloric acid to magnesium, Which of those four are an example of physical change?

Question

aaronq · Answer

which one do you think is right?

anonymous · Answer

I think that it's a trick question and that they all are examples of physical change... But I'm afraid that isn't correct.. Is it?

aaronq · Answer

well think about this, a physical change is typically easily reversible, like melting ice. 
lets run through the options..

A candle burning.. can you easily reverse that? i would think not because it involves combustion which is a chemical reaction.. 

Salt dissolving in water.. are you really changing anything chemically? can you easily get it back?

Vinegar and baking soda producing bubbles.. you're creating gas from the reaction of the 2, it sounds like a physical change, but i't's actually chemical.

Magnesium with HCl.. this is highly reactive and you can't easily get the magnesium back.. so definitely chemical..

anonymous · Answer

So.. none of the above???

aaronq · Answer

salt dissolving in water !

aaronq · Answer

going from solid to aqueous

anonymous · Answer

oh! Foof. I had to re-read what you had written. Sorry. Thank you! You are very helpful!

aaronq · Answer

no problem !  i hope so, and i hope I'm not confusing you :S

anonymous · Answer

X3 For a few seconds I was cofused.. but you set me straight! :D

aaronq · Answer

wooo ;D

anonymous · Answer

:3

aaronq · Answer

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