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Topic: Question about mass percentage in a mixture  (Read 1433 times)

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Offline Smileylover1

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Question about mass percentage in a mixture
« on: April 29, 2022, 11:21:50 AM »
Hello,
There's this one problem I'm having quite a lot of trouble with.
I know that to solve it, you have to find out the 'amount' (coefficients) of each compound in the mixture, but I honestly have no clue on how to do that.

The question goes as follows:

There's a mixture containing K2S, K2SO3 and K2SO4 (unequal amounts of each compound)
The m% of K is 60,0%
How much O is present in this mixture?


Any help would be greatly appreciated, thanks

Online Borek

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Re: Question about mass percentage in a mixture
« Reply #1 on: April 29, 2022, 11:34:27 AM »
If there is 60% of K, can you calculate how much S is present?

(hint: compare all formulas)
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Offline Corribus

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Re: Question about mass percentage in a mixture
« Reply #2 on: April 29, 2022, 11:37:36 AM »
It is also sometimes helpful in problems like this to just assume a certain mass of mixture, like 100 g. Working with absolute masses can be more intuitive than working with mixture %'s. You can then convert back to a % at the end.
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Re: Question about mass percentage in a mixture
« Reply #3 on: April 29, 2022, 03:26:27 PM »
It is also sometimes helpful in problems like this to just assume a certain mass of mixture, like 100 g.

That's my standard advice, but in this particular question it is probably not the most important thing :)
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Offline Smileylover1

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Re: Question about mass percentage in a mixture
« Reply #4 on: April 29, 2022, 05:29:42 PM »
It is also sometimes helpful in problems like this to just assume a certain mass of mixture, like 100 g. Working with absolute masses can be more intuitive than working with mixture %'s. You can then convert back to a % at the end.

Thank you so much! This lead to a break-through

using n=m/M and 100g, and the amount of moles of S being 1/2 of those of K, it worked :)


Offline Smileylover1

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Re: Question about mass percentage in a mixture
« Reply #5 on: April 29, 2022, 05:30:13 PM »
If there is 60% of K, can you calculate how much S is present?

(hint: compare all formulas)

Thank you for the comment, along with another one it helped me find the solution :)

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