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### Topic: How to get atoms of something having % of mass?  (Read 9577 times)

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#### IBM

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##### How to get atoms of something having % of mass?
« on: August 10, 2018, 09:06:27 PM »
Two oxides of a metal contain 27.6% and 30% of oxygen respectively. If the formula of the first oxide is MO, find that of the second?
Now my problem is how to find the atoms of O from the masses of 27.6% and 30.0 %?
How to get atoms of something having % of mass? I am confused.

#### sjb

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##### Re: How to get atoms of something having % of mass?
« Reply #1 on: August 11, 2018, 03:25:09 AM »
If you have, for instance 100g of oxide, what mass is M, and what mass is O? How many moles of each?

#### IBM

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##### Re: How to get atoms of something having % of mass?
« Reply #2 on: August 11, 2018, 05:51:56 AM »
O is 16g and M is (100-16) = 84g. 16g O = 1 mole.

#### sjb

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##### Re: How to get atoms of something having % of mass?
« Reply #3 on: August 11, 2018, 07:03:02 AM »
What do the percentages you have quoted mean?

#### IBM

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##### Re: How to get atoms of something having % of mass?
« Reply #4 on: August 11, 2018, 09:27:44 AM »
In the first MO, if the total amount is 100g, then O is 27.6g similarly,
in the second MO, if the total amount is 100g, then O is 30g respectively

#### sjb

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##### Re: How to get atoms of something having % of mass?
« Reply #5 on: August 11, 2018, 09:50:15 AM »
How many moles of O is 27.6g? In the example of MO, what is the mass of M left and how many moles of it are there?

#### IBM

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##### Re: How to get atoms of something having % of mass?
« Reply #6 on: August 11, 2018, 08:43:40 PM »
1.725 mole of O is 27.6g.
in the MO, 72.4g of M left.
But my question is how to calculate the mole of M? because I don't know the molar mass of M

#### sjb

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##### Re: How to get atoms of something having % of mass?
« Reply #7 on: August 12, 2018, 03:26:44 AM »
In the word MO, what is the ratio of the letters M to O?

#### IBM

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##### Re: How to get atoms of something having % of mass?
« Reply #8 on: August 12, 2018, 04:58:32 AM »
M:O = 1:3 or 13 : 15

#### sjb

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##### Re: How to get atoms of something having % of mass?
« Reply #9 on: August 12, 2018, 05:15:20 AM »
I'm not sure where you get these figures from - care to explain a little more?

#### IBM

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##### Re: How to get atoms of something having % of mass?
« Reply #10 on: August 12, 2018, 08:08:22 PM »
In the word MO, what is the ratio of the letters M to O?

#### sjb

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##### Re: How to get atoms of something having % of mass?
« Reply #11 on: August 13, 2018, 01:41:04 AM »
If you have 1 mole of a compound MO, how many moles of M and how many moles of O do you have?

#### IBM

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##### Re: How to get atoms of something having % of mass?
« Reply #12 on: August 13, 2018, 10:49:04 AM »
1 mole of M and 1 mole of O present

#### sjb

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##### Re: How to get atoms of something having % of mass?
« Reply #13 on: August 13, 2018, 01:30:26 PM »
So in a sample of MO with 1.725 mole of O, how much M is there?

#### IBM

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##### Re: How to get atoms of something having % of mass?
« Reply #14 on: August 14, 2018, 02:05:42 AM »
in 100g MO, M = (100 - 27.6) = 72.4g