Posted by . on Thursday, October 29, 2009 at 12:00pm.
This problem looks simple enough. I would be interested in your thoughts before I go all out on a typing blitz for four questions. Part a is the easiest and you can start there. Cp x M = 25. You are given Cp and you can calculate M.
Tell us what you don't understand (in some detail) if you get stuck.
Here's what I got for:
(a) 69.44 g/mol
(b) 46.4 g M/mol O
I don't understand how to use those two information in order to determine the empirical formula (question (c)). I'm guessing it's some sort of ratio but I don't know how to use the answers that I got for (a) and (b) to solve for (c)
Thanks for you help!
46.4/69.4 = 0.668 = moles M
16/16 = 1 mole O
Now take the ratio. You want small whole numbers with the lowest number being 1. The easiest way to do that is to divide the smallest number by itself, then to keep things equal divide the other number(s) by that same small number.
0.668/0.668 = 1 mole M
1/0.668 = 1.5 moles O
so that is the ratio of 2:3 and the formula is xxxxx?
OK, so the formula is:
...and the identity and atomic mass of the metal M is:
(d) Chromium which has a 51.9 amu
Did I get the answers right?
I wouldn't have gone that route. Isn't the atomic mass of M something like 69.4 (from part a)? Cr isn't close to that although it does form Cr2O3 as the oxide.
Eh, so what is the answer - Ga2O3 (basing it on the atomic mass of part (a))?
That's what I would pick as the oxide and Ga as M.
Great! Thank you so much for all the help, DrBob222!
How did you get the answer on part (B)
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