Saltpeter and Chile saltpeter are two important mineral...

Key Concepts

Percent Composition

Percent composition is the ratio of the mass of a specific element in a compound to the total molecular mass of the compound, expressed as a percentage. This concept is fundamental in determining the contribution of different elements to a compound, especially when evaluating compounds for their nutritional or chemical properties.

Mass Percent Calculation

Mass percent calculation involves summing the contributions of the individual atoms (obtained by multiplying their atomic masses with their counts in the formula) to obtain the total molecular mass, then dividing the mass of the element of interest by the total molecular mass and multiplying by 100. This calculation is central to deriving the mass percent of any element in a compound.

Atomic Mass

Atomic mass is the mass of an individual atom, typically expressed in atomic mass units (amu), and is crucial for calculating the molecular mass of compounds. It provides the weighting factor for each element in a chemical formula, making it possible to determine how much each atom contributes to the overall mass.

Molecular Formula

The molecular formula of a compound indicates the types and numbers of atoms present in the molecule, which is essential to determine its overall molecular mass and the mass contribution of each element. Understanding the molecular formula allows one to break down the compound into its constituent atoms and facilitates further calculations such as percent composition.

Transcript

00:02 So salt peter and chili salt peter are two important mineral sources for nitrogen.

00:09 We have to calculate the mass percent of nitrogen in each mineral.

00:16 So recall that salt peter, let's write that down, peter has the chemical formula k -n -o -3.

00:32 And then for chili salt -peter, we have the formula n -a.

00:41 And all three we're asked to find the mass percent of nitrogen in each mineral so what we need to do is since we're not given any information but we do know the molar mass of each um molecule we can find the molar mass of each element in our molecular formula and then multiply that by or actually divide that by abogado's number to find the grams of our of each one of the each element in our molecular formula.

01:15 And then from there, we can divide the mass of nitrogen by the sum of the masses of our molecular formula.

01:27 So let's begin.

01:29 So we're going to need to start by finding, let's see, we need the mass of k, which is in salt peter.

01:37 So the mass of k is equal to the molar mass of k, which is 39 .10 grams.

01:46 Per mole.

01:47 Now let's divide that by avogadjo's number to just get this in terms of grams.

01:54 So this gives me 6 .5 times 10 to the power of negative 23 grams.

02:01 Now what's next? we need to find the mass of n, but that's equal to 14 .01 grams per mole.

02:11 This is the molar mass of nitrogen times one mole over 6 .022 times 10 to the power of 23.

02:20 Which is equal to 2 .3 times 10 to negative 23 grams...

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