Calculate the number of moles of the indicated substance...

Calculate the number of moles of the indicated substance present in each of the following samples. a. $21.2 \mathrm{g}$ of ammonium sulfide b. $44.3 \mathrm{g}$ of calcium nitrate c. $4.35 \mathrm{g}$ of dichlorine monoxide d. 1.0 Ib of ferric chloride e. $1.0 \mathrm{kg}$ of ferric chloride

Calculate the number of moles of the indicated substance present in each of the following samples.
a. $21.2 \mathrm{g}$ of ammonium sulfide
b. $44.3 \mathrm{g}$ of calcium nitrate
c. $4.35 \mathrm{g}$ of dichlorine monoxide
d. 1.0 Ib of ferric chloride
e. $1.0 \mathrm{kg}$ of ferric chloride

Key Concepts

Mole Concept

The mole is a fundamental unit in chemistry that represents a specific number of particles, typically atoms, molecules, or ions. It provides a bridge between the atomic scale and the mass scale, allowing chemists to count entities by weighing them. One mole is defined as containing exactly 6.022 x 10^23 particles, known as Avogadro's number.

Molar Mass

Molar mass is the mass of one mole of a substance, expressed in grams per mole (g/mol). It is calculated by summing the atomic masses of all atoms in the molecular formula. This value is essential for converting between the mass of a substance and the number of moles.

Mass-to-Mole Conversion

The mass-to-mole conversion is a process that uses the relationship moles = mass/molar mass. This conversion allows chemists to translate a measured mass into the number of moles of a substance, which is a vital step in quantifying the amount of reactants and products in a chemical reaction.

Unit Conversion

Unit conversion is the process of converting quantities from one unit to another to ensure consistency in calculations. This is especially important when dealing with different units of mass, such as converting pounds to grams or kilograms to grams, so that the mass used in mole calculations corresponds correctly to the molar mass units of g/mol.

Transcript

00:01 Here we have five compounds and we have their mass and we are trying to find their number of moles and the number of moles in each mass.

00:13 So we're calling the formula for moles.

00:17 We know that it's mass over molar mass.

00:22 So all we're going to do is take the mass is given and divided by their molar mass.

00:27 All right.

00:28 So let's get started.

00:29 Here we have ammonium sulfide.

00:35 So to find ammonium sulfide's molar mass, we simply sum up the molar mass of each individual element in this compound.

00:46 And we also have to take into account the number of atoms of each element.

00:52 And yeah, when summing that up, i found it to be 68 .154 grams per mole.

01:04 Okay, and if we do this division, the quotient comes up to being 0 .3116, if we were to have kept all the units.

01:31 Okay, that's the routine.

01:35 Next, we have calcium nitrate, and we have 44 .3 grams of it.

01:40 So after calculating the molar mass, found it to be 164 .088 grams per mole.

01:59 After this division, the number of moles is 0 .269 moles.

02:18 Okay.

02:19 Next up, we have dichloric.

02:27 Dichlorine monoxide.

02:30 Diaclorine monoxide.

02:34 So the molar mass of dichlorine monoxide is 86 .9 grams per mole.

02:46 Mm -hmm.

02:58 When we do this division, we get the number of moles coming out to be 0 .05 moles.

03:13 Okay, next up we have iron.

03:17 Trichlorite.

03:21 So here we have one pound, but we must work in grams.

03:26 If we're going to use molar mass, grams per mole.

03:30 So let's do a nice unit conversion...

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