What is the empirical formula of the ingredient in Bufferin tablets that has the percent composi

What is the empirical formula of the ingredient in Bufferin...

Key Concepts

Chemical Formula Determination from Percent Composition

After obtaining the mole ratios, one compares the calculated ratios with known chemical compounds. In this context, matching the computed percentages to known atomic masses leads to identifying the compound's empirical formula.

Mole Ratio Calculation

This key step involves dividing the percent by the atomic mass of each element to calculate the number of moles present in a hypothetical 100 g sample. These mole values are then compared to determine the simplest ratio among the elements.

Percent Composition

This concept explains how the mass of each element contributes to the total mass of a compound, expressed as a percentage. It is the basis for determining how much of each element is present in a given sample and is essential for subsequent calculations.

Empirical Formula

The empirical formula of a compound is the simplest whole-number ratio of atoms of each element present. It is deduced from percent composition by converting the mass percentages into moles and then reducing these amounts to the smallest whole numbers.

Transcript

00:01 We are given the mass percent composition of a compound and asked to find its empirical formula.

00:08 To understand how we're going to find the empirical formula, it helps us to know what it is.

00:13 To recall that the empirical formula gives the simplest whole number ratio of atoms in a compound.

00:23 Now, because we're dealing with number of atoms, we can't work in units of mass.

00:30 That's not going to be sufficient.

00:31 When we're dealing with atoms and things that we can count, the units that we work with in chemistry are moles.

00:38 So when we write an empirical formula for this compound, c -o -m -g, the coefficients represent number of atoms, and we work with units of moles.

00:52 So we need to take this percent composition, which gives us information about mass, and first change it into moles.

01:01 To that end, we're going to make an assumption.

01:05 Now, we could have a gram of this compound, 100 grams, a thousand grams, a ton, and it wouldn't matter.

01:13 We would still have 14 % carp.

01:16 So to make our lives easy, we're going to make the assumption that we're working with 100 grams of compounds.

01:31 Well, if we have 100 grams of compounds, then we must have 14 .25 grams of carbon, 56 .93.

01:47 Grams of oxygen and 28 .83 grams of magnesium.

01:57 Cool.

01:58 Now remember what we said.

02:01 Working with grams isn't going to help us with a formula that involves a number of atoms.

02:05 So we need to change these number of grams to moles.

02:09 And to do that, we need to divide by the molar mass for each of these substances.

02:13 But for carbon, that means dividing by one mole of carbon for every 12 .01...

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