ssNake's Chemistry [u2] Q's

[REBORN]

like that's a type of Q when you work out limiting and all that....when there are two reactants given with data.

[Lasercookie]

guys don't revise for chem....lets all start together after my spesh exam..

Don't worry, we won't start revising before you.

Seeing that this is a Unit 2 thread, we'll be starting revision in about 10 months time (exact number of months would vary). 

[REBORN]

Q - 70.0g of an ionic compound is dissolved in 1L of pure water, which immediately turned the solution blue. The anion concentration was found to be 1.377M. Identify the ionic compound.

[BlueSky_3]

For some reason I kept on getting sulfur nitrate.....but i think i'm most likely wrong so i too want to know how to do this question

Edit: WTF? can't be sulfur that's an anion what was i thinking ...... wait it must be copper something right?

[REBORN]

Turns solution blue = Cu2+

dw bout it, I received help from a chem genius.

[thushan]

LOL snake that's nice of you!

[BlueSky_3]

@snake: lemme guess Thushan?

Anyways what is the answer? And how did you derive it Thushan???

[thushan]

Oh, I got CuF2 - I assumed Cu2+ from blue, assumed -1 charge on anion coz it looked like that must be the case (judging on numbers given) then did calcs and got molecular weight of anion = 19, F-.

[BlueSky_3]

Hmmm...how did you simply deduce that the charge must be negative 1 on anion? are there any specific rules regarding those which we must know for unit 3/4 chem? Oh and what about the colours of solutions i.e. apart from blue= cu 2+ are there anymore which are also a good idea to know?

[thushan]

Hunch. It was given that mass was 70.0 g and conc of anion was 1.377 M. If charge on anion was -2, then there would only be a single anion and so [salt] = [anion] = 1.377 M so molecular mass of salt = 70/1.377 < 63.6...so it kinda doesnt work.

[BlueSky_3]

Yeah I tried that and thats probably why it didn't make sense. Hmmm....interesting question and thanks for that