Stoichiometry question! Help, please Watch

amamsy
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Q- on heating, 0.02 mol of the element M reacts with 0.025 mol of Oxygen gas. What is the empirical formula of the Oxide of M?
I tried doing this question, but I keep getting a wrong answer! :dontknow:

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username1445490
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What empirical formula do you get?

The numbers in the empirical formula are the lowest whole number mole ratios.
You have a mole ratio of 0.02 : 0.025 but it isn't a whole number ratio so you need to divide them both by the smallest number to get a 1: something ratio and then multiply them until they are both whole numbers and put those into the empirical formula.
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Borek
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(Original post by Madasahatter)
You have a mole ratio of 0.02 : 0.025
Actually - no, that's not the mole ratio you have.

What do you know about oxygen?
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username1445490
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(Original post by Borek)
Actually - no, that's not the mole ratio you have.

What do you know about oxygen?
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amamsy
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(Original post by Madasahatter)
What empirical formula do you get?

The numbers in the empirical formula are the lowest whole number mole ratios.
You have a mole ratio of 0.02 : 0.025 but it isn't a whole number ratio so you need to divide them both by the smallest number to get a 1: something ratio and then multiply them until they are both whole numbers and put those into the empirical formula.
Thanks for answering, I discussed the question with my chemistry teacher today, so I'm good We need to multiply the 0.025 by 2, because Oxygen gas is always in molecules, but we need to use atoms for the empirical formula.
*Then* we do the dividing by the smaller number (0.02). The ratio is then 1 : 2.5.
It's a multiple choice question (sorry,I forgot to mention that earlier! ) And the answer is M2O5.

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