WEBVTT
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to describe the composition or makeup of a chemical compound
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or molecule. There are three different ways in which
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we can describe the elements president. The first is
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called the empirical formula, which is the lowest whole
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number ratio of moles of each element in the compound
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. So for examples, a compound might have an
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empirical formula of C H three. This means for
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every mole of carbon, there are three moles of
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hydrogen. The molecular formula is the actual ratio of
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moles of Utah, element in a compound, and
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it's usually a multiple of the empirical formula. So
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a molecular formula for a compound that exists to see
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to H six and you can see that this means
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that there are two moles of carbon and six moles
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of hydrogen in one mole of the compound, you
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can see this is a multiple of the empirical formula
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. Finally, a structural formula is a picture or
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a drawing that shows how everything is arranged in the
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Adam. So this is usually the molecular formula,
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but drawn as a picture. So this would be
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an example of a structural formula. You have two
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carbons and six hydrogen around each carbon, so the
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question is, what information do you need to have
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to determine the molecular formula? If you know the
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number of moles of each type of Adam and the
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sample of compound, this is Onley enough to tell
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you the empirical formula. So a is not enough
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information. If you have the mass of each element
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and the total number of atoms in a molecule the
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compound you can use this information to find the molecular
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formula. The first step is ticked, a mass
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of each element and change it to moles. And
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you do this by using the molar mass. Once
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you have the moles of each element, you confined
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the ratio. And this allows you to write the
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empirical formula. To find the molecular formula, we
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have to compare total number of Adams and the empirical
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formula to the total number of atoms in the molecule
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. So after you found the empirical formula, you
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find total number of atoms in the molecule divided by
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the atoms. In the empirical formula. This gives
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us the multiplier and then you can find the molecular
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formula. Similarly, if you have the mass,
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each element in the total number of Adams of only
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one element. We can still use that to find
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the ratio of the empirical formula to molecular formula.
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So see also gives us enough information. Follow the
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same steps to find the empirical formula. And then
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we confined the ratio between the number of atoms of
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one element in the empirical formula and the Adams one
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element in a molecule, and this again gives us
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the multiplier to find the molecular formula. If we
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know the empirical formula and massive each element, that
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is not enough information to find the ratio between molecular
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an empirical formula. Finally, given a structural formula
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, this is perhaps the most informative, and you
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can use it to find the molecular formula, and
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you do this simply by counting up the number of
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each Adam present.