Suppose you know the mass per mole (in units of g / mol ) of a substance. (a) Without doing any

step 1 Okay, so let's consider a scenario. Okay, so we know mass per mole 2S's of a certain atom. So wi

Suppose you know the mass per mole (in units of g / mol ) of...

Suppose you know the mass per mole (in units of $\mathrm{g} / \mathrm{mol}$ ) of a substance. (a) Without doing any calculations, how can you determine the mass of one of its atoms (expressed in atomic mass units)? (b) What information about the sample is obtained when you divide its mass by the mass per mole? Problem A certain element has a mass per mole of $196.967 \mathrm{~g} / \mathrm{mol}$. What is the mass of a single atom in (a) atomic mass units and (b) kilograms? (c) How many moles of atoms are in a $285-\mathrm{g}$ sample?

Suppose you know the mass per mole (in units of $\mathrm{g} / \mathrm{mol}$ ) of a
substance. (a) Without doing any calculations, how can you determine the mass of one of its atoms (expressed in atomic mass units)? (b) What information about the sample is obtained when you divide its mass by the mass per mole? Problem A certain element has a mass per mole of $196.967 \mathrm{~g} / \mathrm{mol}$. What is the mass of a single atom in (a) atomic mass units and (b) kilograms? (c) How many moles of atoms are in a $285-\mathrm{g}$ sample?

Key Concepts

Mole Concept

The mole concept is the foundation of quantifying substances in chemistry. It defines a mole as the amount of substance containing as many entities as there are atoms in 12 grams of carbon-12. Dividing the mass of a sample by its molar mass yields the number of moles, which is a measure of the amount of substance present in the sample.

Avogadro's Number

Avogadro’s number is a fundamental constant that represents the number of particles (atoms, molecules, ions, etc.) in one mole of a substance, approximately 6.022 x 10^23. This constant is key in converting between the number of discrete particles and the amount in moles, thus linking microscopic and macroscopic world measurements.

Unit Conversion (Mass and Weight)

Conversion between different mass units, such as from atomic mass units to kilograms or grams, is an essential concept. For instance, knowing that 1 amu corresponds to 1.660539 x 10^-27 kilograms facilitates the translation between atomic-scale masses and the larger-scale masses measured in laboratories. This conversion is crucial when calculations require expressing results in SI units.

Molar Mass

Molar mass is the mass of one mole of a substance, usually expressed in grams per mole. It numerically matches the atomic or molecular mass when the mass is measured in atomic mass units (amu), providing a bridge between the atomic scale and macroscopic quantities. This allows one to determine the mass of a single atom or molecule by recognizing that 1 amu is equivalent to 1 g/mol on a numerical basis.

Atomic Mass Unit

An atomic mass unit (amu) is a convenient unit for expressing the masses of individual atoms and molecules. It is defined such that one atom of carbon-12 has a mass of exactly 12 amu, making it directly relatable to the molar mass scale where 1 amu corresponds to 1 g/mol. This definition simplifies the conversion between the mass of a single atom and the molar mass of a substance.

Transcript

00:04 Okay, so let's consider a scenario.

00:07 Okay, so we know mass per mole 2s's of a certain atom.

00:24 So without doing any calculations, how would we refine the mass of a given atom? so to cover ways to do it, you could either take the unit value for atomic mass units, unit conversion for atomic mass units, which is one atomic mass unit is equivalent to 1 .6 .605 times 10 to negative 27 kilogram.

00:52 So you could just take that value, multiply it by this, and you'll have the weight of a single atom.

01:00 Alternatively, you could say take the periodic table atomic mass unit's value, and you could divide it by apogadro's number.

01:08 This would work because you'd be atomic mass units which are basically grams per mole then you can take one divided by abogadro's number of particles which would give you the number of grams per given atom now how would we determine the number of moles set of a certain substance given the mass well if we had the atomic mass too we can just take the mass and divide it by the am to you the atomic mass units which are just, yeah, let's write it away.

02:03 Basically, atomic mass units are just in grams.

02:09 Units mass per mole.

02:12 So we know the mass units would cancel out, but we'd just be left with the way.

02:18 So basically, you take mass, divide it by atomic mass unit value from your periodic table just below the letter that corresponds to the element.

02:34 So we're given another problem.

02:38 Let's start with part a.

02:42 It's doing otherwise be a travesty.

02:49 So how do we find, say we're given 196 grams per mole.

02:59 How do we find that value in atomic mass units? or what is the mass of a single, single atom in atomic mass units? so let's go ahead and solve for that.

03:15 So it's grams per mole or grams for mole is equivalent to units.

03:39 So it's just 196 .967 atomic mass units.

03:45 They're the same thing...

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