February 28, 2017

Homework Help: chemisty

Posted by STACY on Tuesday, December 14, 2010 at 4:41pm.

Posted by STACY on Monday, December 13, 2010 at 7:56pm.

Consider an aqueous solution prepared from 250.0 mL of water and 1.27 g of potassium bromide. Express the amount of potassium bromide in this solution in terms of
(a) mass percent
(b) mole fraction
(c) molarity
assume the density of the solution is equal to that of water, 1.00 g mL-1.........help!

CHEMISTRY - DrBob222, Monday, December 13, 2010 at 8:54pm
Surely you don't want me to work all three. Surely you know SOMETHING about SOME of them. Just remember the definitions:
1. mass percent. grams solute/100 g solution.
2. mole fraction. moles solute/total mules.
3. molarity = moles/L of solution.
Apply those three definitions and you will have your answer(s).
Post your work if you get stuck.

CHEMISTRY - STACY, Tuesday, December 14, 2010 at 4:40pm
I surely do, and don't call me Shirley! LOL yessss i'm sorry I don't know much about chemistry that's why i'm here!!

1. Mass percent= grams solute/100solution 1.27g/250.0mL = 5.08x10^-03 is my answer but the correct one is 0.505%

2. Mole fraction= moles solute/total moles ?/119.002

3. Molarity 1.27g/119.002= 0.0107moles
than 0.0107/0.25L = 0.048 that's my answer but the correct one is 4.25x10^-2

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