Calculate the number of moles of hydrogen atoms present in each of the following samples. a. 2.7

Calculate the number of moles of hydrogen atoms present in...

Key Concepts

Mole Concept

The mole is a fundamental unit in chemistry that represents a specific quantity of particles, typically atoms or molecules. One mole is defined as containing exactly 6.022 x 10^23 of these entities, and it is used to convert between the number of atoms or molecules and the mass of a chemical substance.

Molar Mass

Molar mass is the mass of one mole of a substance, usually expressed in grams per mole (g/mol). It is determined by summing the atomic masses of each element as given in its chemical formula, and it serves as a conversion factor between the mass of a substance and the number of moles.

Chemical Formulas

Chemical formulas represent the composition of molecules and compounds by indicating the number of atoms of each element present. Understanding the chemical formula is critical in stoichiometry as it informs the ratio of atoms in a molecule, which is necessary for calculations involving the number of atoms per mole of substance.

Stoichiometry

Stoichiometry involves the quantitative relationships among reactants and products in a chemical reaction, based on the coefficients in the balanced chemical equation. It is essential for determining the number of atoms or molecules of a given element when the amount of a compound is provided.

Dimensional Analysis

Dimensional analysis is a problem-solving technique used to convert one set of units to another. In chemistry, it is applied to convert between mass, moles, and number of particles by using conversion factors such as molar mass and Avogadro’s number.

Transcript

00:01 Okay, so here we have four compounds, and we're doing something a bit different.

00:05 We are finding the moles of hydrogen atoms in particular, right? okay, so in order to do that, we will first find the moles of the whole compound, which we know the formula for moles is mass over molar mass, and it'll be mass of the whole compound divided by the molar mass of the entire compound.

00:37 Right? so now in order to take moles of the whole compound to the molds of the mold of hydrogen, we need to understand like how these molar ratios work.

00:54 So we know that just by looking at it, we have ammonia here.

00:59 One mole of ammonia will always.

01:02 Have one mole of nitrogen for every three moles of hydrogen.

01:10 So like we really need to understand what these subscripts here means.

01:14 So they are basically molar ratios of each other.

01:18 So one mole of ammonia, one mole of nitrogen, three moles of hydrogen.

01:26 Yeah, i hope that makes sense.

01:28 So that's basically what we're going to do to solve all of these.

01:34 Questions? okay.

01:35 So here, ammonia.

01:38 2 .71 grams of ammonia divided by the molar mass of ammonia, which found to be 17 grams per mole.

01:50 Right? so that equals 0 .159 moles of ammonia is present now.

02:07 Right? so to find moles.

02:12 Of hydrogen, what we basically are going to do now, let me use another color, i guess, is multiply total moles by you guessed it three.

02:27 Because for every mole of monia, we have three extra moles of hydrogen, just because of the subscript here.

02:38 Right, so then this multiplied by three gives us 0 .477 moles of hydrogen.

02:48 Yeah, i know it's interesting.

02:50 I'm a bit counterintuitive that we would have more moles of hydrogen than of ammonia, but if you really understood what i just said like a minute ago, it makes sense.

03:06 Because there are more molds of hydrogen than there are atoms, or not atoms, compounds of ammonia.

03:15 So let me say that again.

03:16 There are more moles of hydrogen atoms than there are of oresidents.

03:20 Ammonia molecules because there's three times more.

03:25 Okay, i think it makes sense now.

03:27 Okay, now we're moving on to water...

Please give Ace some feedback