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Problem 102 Medium Difficulty

A magnesium salt has the following elemental composition: 16.39$\%$ Mg, 18.89$\%$ N, 64.72$\%$ O. Determine the empirical formula of the salt.

Answer

$\mathrm{MgN}_{2} \mathrm{O}_{6}(\text { or }) \mathrm{Mg}\left(\mathrm{NO}_{3}\right)_{2}$

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Video Transcript

Okay, so here we're again finding empirical formula, and we've been nicely given the mass percent of each element. So we have magnesium, nitrogen, oxygen. So the one for magnesium 16.39 the one for a nitrogen with compound is 18 point 8 to 9% nitrogen and 64 0.72% oxygen. So to find the empirical formula to find the ratio of each element to on one another, we need to work. You need to use moles. No, isn't. Sees Mel's. So to find malls, we need to find mass. And by the Bible, A mass. Okay, so we have mass percent, which is basically a mass. Yeah, And if you were to have, you know, ah, 100 grams of substance, this would be of mass. So we will use this. His mask invited by the molar mass of each moment we're gonna take for magnesium 16.39 And the by the by it's more mass, which is 24.3 to give us a number of malls of six point of 0.6743 And for a nitrogen, we take 18.89 and divided by 14. It's for most. It was 1.34 feet. And then for oxygen. You take this mass 64.2 divided by its more mascot like 16. That gives us basically four. All right, so now these numbers are supposed to give us You prefer formula, but they look a bit here. And so we're going to do some division. Are you their 0.67 divided by 0.67 be sent. Its the smallest number, which is one I'm gonna take, um, 1.34 and divided by this number, which comes out to being too analytic. Four and again divided by this number. Springs comes about 26 All right to them. There we have it. Nice and easy. Magnesium one nitrogen to oxygen. 606 So you don't have to write this this way, But if you can just like, we'll get it. This is magnesium nitrate. Yeah, just m Jean Anne 03 to Yeah, so, yeah, there's no leg trip as to knowing what actually is. You look at it in, be familiar enough with chemical compounds to know to recognize what it is. So both are correct. It doesn't. It doesn't really matter.

McMaster University
Top Chemistry 101 Educators
Stephanie C.

University of Central Florida

Lizabeth T.

Numerade Educator

Nadia L.

Rice University

Jake R.

University of Toronto