What number of atoms of phosphorus are present in 1.00 g of each of the compounds in Exercise 54

What number of atoms of phosphorus are present in 1.00 g of...

Key Concepts

Mole Concept

The mole concept is a fundamental principle in chemistry that provides a bridge between the mass of a substance and the number of particles it contains. By converting grams to moles using the substance's molar mass, we can determine the amount of a compound in terms of the number of moles, which is a key step in quantifying atoms, molecules, or ions.

Avogadro's Number

Avogadro's number, approximately 6.022 x 10^23, is the number of entities (such as atoms or molecules) in one mole of any substance. This constant is crucial for converting the amount in moles to the actual number of atoms, which allows us to determine the total count of phosphorus atoms in a given mass.

Molar Mass

Molar mass is the mass of one mole of a substance, expressed in grams per mole (g/mol). It is used to convert a given mass of a compound to the number of moles. Accurately determining the molar mass of a compound is essential for stoichiometric calculations, where the mass of a substance is related to the number of constituent particles.

Stoichiometry

Stoichiometry involves using the relationships between reactants and products in a chemical equation to calculate the quantities of substances involved. In the context of this problem, stoichiometry is used to connect the number of moles of a compound to the number of phosphorus atoms present, by taking into account the chemical formula and the number of phosphorus atoms it contains.

Transcript

00:02 Hi there.

00:02 Previously in problem number 54, we calculated the molar mass for the three compounds in number 54.

00:11 Those were p406, which had a molar mass of 219 .88 grams per mole.

00:26 We had ca3, p .o .4, 2, with a molar mass of 3, 2, with a molar mass of 3, 2.

00:39 10 .18 grams per mole.

00:45 And then we had letter c, which was na2hpo4, which had a molar mass of 141.

01:01 .96 grams per mole.

01:06 For this problem, in each of these, we want to know how many phosphorus atoms we would have if we have one gram of each of these substances.

01:15 So, sounds like a little bit of stoichiometry here.

01:18 Let's go ahead and get started.

01:20 So we have one.

01:21 0 .00 grams of p4 .06.

01:30 So the first thing i want to do is use that molar mass to convert to moles.

01:35 There are 219 .88 grams of the p4 .06 in every mole of it.

01:52 Now that i have moles, i can use avogadros number in one mole of anything, in this case, our anything is p406, there are 6 .02 times 10 to the 23rd molecules.

02:14 In this instance, those are molecules of p406.

02:19 We don't want to know the number of molecules.

02:21 We want to know how many phosphorus atoms we have.

02:24 So we need to do one more step.

02:27 Looking at the formula for this, we see that in one molecule of p4 -06, there are four atoms of phosphorus.

02:45 Right now we can calculate the answer because molecules will cancel, moles will cancel, grams will cancel, and we will obtain an answer in number of atoms.

02:59 This answer is 1 .10 times 10 to the 20.

03:07 2nd atoms of phosphorus.

03:14 So even in just one gram of this we have an extremely high number of atoms of phosphorus.

03:24 All righty, let's move on to letter b where we are just going to repeat this process, but this time we are starting off with one gram of ca3, p .04.

03:41 First step is going to be to divide by molar mass 310 .18 of ca3.

03:52 P .o .4 .2...

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