Easiest Chemistry Question Ever

basilmarket.com forums : Chat | 13 posts archived

thread starter frozenmage Sep 26 2010 + PM | QUOTE | PERMALINK | REPORT

Hey guys, can anyone help me with this? Thanks ! An unknown sample weighed 2.129 g. It contains CoCl2 • 6H2O and NaCl and was heated to drive off all of the water (CoCl2 • 6H2O --heat--> CoCl2 + 6H2O). The solid residue that remained weighed 1.712 g. Calculate the percentage of CoCl2 • H2O in the unknown sample.

My Characters: LuminousFire - 122 Broa F/P Arch Mage

tiganior1 + PM | QUOTE | PERMALINK | REPORT

I've had enough of chemistry tonight. I'll help in a bit. http://www.emporia.edu/chemist/davies/third.htm

My Characters: zezima4960 - 72 Broa Ranger

Podunkman 09/26/10 + PM | QUOTE | PERMALINK | REPORT

wait what? if it was heated to remove the water, then how is water still a product?

My Characters: SuperBow77 - 50 Scania Hunter

MsDit 09/26/10 + PM | QUOTE | PERMALINK | REPORT

subtract masses thats how much h2o there is add mass of CoCl2 to 6H2O divide that by 2.129

My Characters: AznSinDit200 - 105 Windia Chief Bandit

frozenmage 09/26/10 + PM | QUOTE | PERMALINK | REPORT

[quote] Podunkman : wait what? if it was heated to remove the water, then how is water still a product? [/quote] i have no idea I don't know if its a typo in my workbook or what...or maybe its intended

My Characters: LuminousFire - 122 Broa F/P Arch Mage

Podunkman 09/26/10 + PM | QUOTE | PERMALINK | REPORT

frozenmage just right "no". but seriously that question makes no sense.

My Characters: SuperBow77 - 50 Scania Hunter

punkgx1 09/26/10 + PM | QUOTE | PERMALINK | REPORT

im in 9th grade what is this

My Characters: MorninKnight - 59 Windia Dawn Warrior

tiganior1 + PM | QUOTE | PERMALINK | REPORT

[quote] frozenmage : i have no idea I don't know if its a typo in my workbook or what...or maybe its intended [/quote] I don't want to think right now. But didn't you get all of the H2O out of the sample when you heated it? So shouldn't it all just be CoCl2? You can probably find individual moles and weights, along with a formula, but I'm too lazy to plug it in right now. =/ Check out that link I gave you.

My Characters: zezima4960 - 72 Broa Ranger

frozenmage + PM | QUOTE | PERMALINK | REPORT

[quote] tiganior1 : I don't want to think right now. But didn't you get all of the H2O out of the sample when you heated it? So shouldn't it all just be CoCl2? You can probably find individual moles and weights, along with a formula, but I'm too lazy to plug it in right now. =/ Check out that link I gave you. [/quote] Well the question says that it contains NaCl also, so when you remove the water the residue (1.712 g) would have the NaCl in it also i'm guessing. The question asks for the percentage of CoCl2 • 6H2O soooo i dunno edit: oh and thanks for the link, i'm checking it out right now

My Characters: LuminousFire - 122 Broa F/P Arch Mage

tiganior1 09/26/10 + PM | QUOTE | PERMALINK | REPORT

[quote] frozenmage : Well the question says that it contains NaCl also, so when you remove the water the residue (1.712 g) would have the NaCl in it also i'm guessing. The question asks for the percentage of CoCl2 • 6H2O soooo i dunno edit: oh and thanks for the link, i'm checking it out right now [/quote] NaCl is sodium chloride. Or table salt.

My Characters: zezima4960 - 72 Broa Ranger

CommanderZeb 09/26/10 + PM | QUOTE | PERMALINK | REPORT

Well the little bullet point/dot thing between CoCl2 and 6H2O means that the water is part of the compound, but once you add heat the water comes off and you are left with water AND the CoCl2, but they aren't attached. Unfortunately I can't quite remember what else to do, but I thought i might clarify that..

My Characters: Uberville - 73 Windia Sniper

frozenmage + PM | QUOTE | PERMALINK | REPORT

[quote] tiganior1 : NaCl is sodium chloride. Or table salt. [/quote] yea, so how do I account for that in the calculation? The residue is 1.712 so i'm assuming the salt is included in addition to the CoCl2. So the percent of CoCl2 and NaCl would be • (1.712 / 2.129) * 100 = 80.4% The percent of water removed would be • (0.417 / 2.129) * 100 = 19.6% So roughly both add up to 100%. The thing is the 80.4% includes both the salt and the CoCl2 and the question asks for just CoCl2. This is confusing

My Characters: LuminousFire - 122 Broa F/P Arch Mage

wasdf 09/26/10 + PM | QUOTE | PERMALINK | REPORT

If only this was physics...

My Characters: wasdff - 135 Scania Shadower