Asbestos and Lung Disease Inhalation of asbestos fibers may...

Asbestos and Lung Disease Inhalation of asbestos fibers may lead to a lung disease known as asbestosis and to a form of lung cancer called mesothelioma. One form of asbestos, chrysotile, is $26.31 \%$ magnesium, $20.27 \%$ silicon, and $1.45 \%$ hydrogen by mass, with the remainder of the mass as oxygen. What is the empirical formula of chrysotile?

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Key Concepts

Empirical Formula

The empirical formula represents the simplest whole-number ratio of atoms of each element in a compound. It is determined by converting the mass of each element (often given as percentages) to moles and then finding the simplest ratio among those moles.

Percent Composition

Percent composition describes the percentage by mass of each element in a compound. It forms the basis for calculating the number of moles of each element when determining the empirical formula, by assuming a convenient total mass (often 100 grams) for calculation purposes.

Mole Concept

The mole concept is essential for converting between the mass of an element and the number of atoms or molecules. By dividing the given mass (or percent by weight) of each element by its atomic weight, one can calculate the number of moles, which is fundamental to establishing the ratios necessary for the empirical formula.

Stoichiometry

Stoichiometry involves the quantitative relationships between reactants and products in chemical reactions, but in this context, it refers to the method of using mole ratios derived from percent composition to determine the relative proportions of each element in a compound.

Transcript

00:01 All right, so we're giving a little bit of information about a compound, and we're going to try to determine its empirical formula.

00:07 We're told that this compound is 26 .31 % magnesium, 20 .27 % silicon, 1 .45 % hydrogen, and the rest is oxygen.

00:18 So the first thing we have to do is to determine how much of this is oxygen from these numbers.

00:24 So it's going to be 100 % at all.

00:26 We're going to add all of these up, subtract it from 100, and you'll see that the number that we're left with is 51 .97%.

00:37 So 51 .97 % of this compound is going to be oxygen.

00:41 The next thing that we're going to do to determine the lowest molar ratio in between these elements is going to divide each percentage by its molar mass.

00:53 So first off here, we're going to have magnesium, which has a molar mass of 24 .305.

01:00 So we're going to take 26 .31 and divide that by 24 .305.

01:11 And we can go ahead and see that that is going to be 1 .08.

01:19 Okay.

01:20 For silicon, it's going to be 20 .27 over its smaller mass, which is 28 .08.

01:31 And that's going to give us 0 .72.

01:35 Right here, hydrogen, it's just one.

01:40 The atomic mass of hydrogen is just one.

01:43 So we can just go ahead...