September 18, 2019, 03:23:08 AM
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Topic: Substance left after evaporation- is it a new chemical?  (Read 453 times)

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Offline puddi_puddi

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Substance left after evaporation- is it a new chemical?
« on: February 14, 2019, 06:33:35 PM »
hi!
i'm really sorry if this question is ridiculous. it's my first time posting so let me know if i should go elsewhere.

i did a lab today where we mixed 2g of a CaCl2 + CaCO3 mixture with 10mL deionized water. we put the solution through a filter and boiled the resulting filtrate. when all of the water was boiled out, there was a crusty white solid left.

i'm trying to figure out what this white solid was. i don't think there was a chemical change (there was no fizzing/bubbling, color change, effervescence, or immediate precipitation formation. solid only formed when the water turned into vapor), so i think it's either CaCl2 or CaCO3, not a new chemical. but i could be wrong.

how do i know what it is? what are the clues?

thank you so so much!!

Offline puddi_puddi

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Re: Substance left after evaporation- is it a new chemical?
« Reply #1 on: February 14, 2019, 08:00:04 PM »
i don't mean to HURR DURR BOOST or whatever, but i think i might have found the solution! i don't know if it's correct but i think i'm onto something.

the key i think is that CaCO3 is insoluble in water. so logically it got left behind in the filter paper at least mostly, right? which means the filtrate was (mostly) just water and CaCl2. which means boiling off the water would leave only the CaCl2, right?

i guess i feel unsure because the CaCl2 is all crusty and off-white instead of the chunky solid that it was before. plus, i'm having a hard time believing that all of the CaCO3 was left behind in the filter.

i think for now though, that's the answer i'm going with. please let me know if i've made a mistake m(_ _)m

Offline AWK

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Re: Substance left after evaporation- is it a new chemical?
« Reply #2 on: February 15, 2019, 02:57:51 AM »
OK
AWK

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