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Topic: How to get atoms of something having % of mass?  (Read 9845 times)

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Offline sjb

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Re: How to get atoms of something having % of mass?
« Reply #15 on: August 14, 2018, 02:15:32 AM »
How many moles of M?

Offline IBM

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Re: How to get atoms of something having % of mass?
« Reply #16 on: August 14, 2018, 02:13:04 PM »
1 mole of M

Offline sjb

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Re: How to get atoms of something having % of mass?
« Reply #17 on: August 14, 2018, 04:09:55 PM »
No, if there are for example 2 moles of O in a sample of MO, how many moles of M are there?

Offline IBM

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Re: How to get atoms of something having % of mass?
« Reply #18 on: August 14, 2018, 09:49:38 PM »
2 moles of M are there
2M + 2O2 = 2MO

Offline sjb

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Re: How to get atoms of something having % of mass?
« Reply #19 on: August 15, 2018, 01:17:28 AM »
So in a sample of MO with 1.725 mole of O, how much M is there? (Ignoring the improperly balanced equation as that's not relevant at the moment)

Offline IBM

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Re: How to get atoms of something having % of mass?
« Reply #20 on: August 15, 2018, 02:50:22 AM »
1.725 moles of M weighs 74.4g
So, 1 mole of M weighs 74.4/1.725 = 43.13g 

Offline sjb

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Re: How to get atoms of something having % of mass?
« Reply #21 on: August 15, 2018, 03:45:42 AM »
Good, so in 100g of your second sample containing 30.0 % O, what is the mass of M, how many moles of M and O do you have?

Offline IBM

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Re: How to get atoms of something having % of mass?
« Reply #22 on: August 15, 2018, 02:35:15 PM »
70g of M,
1.875 moles of O and M

Offline sjb

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Re: How to get atoms of something having % of mass?
« Reply #23 on: August 15, 2018, 03:29:40 PM »
No, if the sample is 70g of M, with molecular weight 43.13g mol-1, what is the number of moles? (Does it make sense for both numbers of moles to be increased from your first sample?)

Offline IBM

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Re: How to get atoms of something having % of mass?
« Reply #24 on: August 16, 2018, 01:47:14 PM »
43.13g = 1 mole So, 70g = (70/43.13) = 1.62 moles

Offline sjb

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Re: How to get atoms of something having % of mass?
« Reply #25 on: August 16, 2018, 03:49:44 PM »
So what is the ratio in your second sample?

Offline IBM

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Re: How to get atoms of something having % of mass?
« Reply #26 on: August 16, 2018, 08:32:57 PM »
But how to calculate the moles' of O in the second sample?
would it be 43.13g O = 1 mole
               So, 30g O =.69 mole
So. the ratio in the second sample is M:O = 1.62:.69 = 54:23
« Last Edit: August 16, 2018, 08:47:40 PM by IBM »

Offline sjb

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Re: How to get atoms of something having % of mass?
« Reply #27 on: August 17, 2018, 08:00:50 AM »
You knew the mass of oxygen for sample 2 right at the start, and the atomic mass of oxygen is readily available.

Offline IBM

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Re: How to get atoms of something having % of mass?
« Reply #28 on: August 17, 2018, 02:33:20 PM »
So, what to do now?

Offline IBM

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how to calculate 'mole', 'molar mass' and 'molecular mass'?
« Reply #29 on: August 25, 2018, 01:50:41 PM »
Two oxides of a metal contain 27.6% and 30% of oxygen respectively. The formula is MO.
Now my questions are below:
In the case of the first formula MO:
1. If the compound is 'MO' as a product, The reactant would be 'M +0.5 O2 = MO'
So if the total amount is 100 g (MO), M + 0.5 O2 =100g. From this equation in the left side, what will be the mass of O and M (not from the MO because I am able to calculate the mass of O and M from 'MO')?

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