On réalise la réaction dont l'équation stœchiométrique s'écrit : 2 NH3+5 F2 =N2 F4+6 HF. On ut

On réalise la réaction dont l'équation stœchiométrique...

On réalise la réaction dont l'équation stœchiométrique s'écrit : $2 \mathrm{NH}_3+5 \mathrm{~F}_2$ $=\mathrm{N}_2 \mathrm{~F}_4+6 \mathrm{HF}$. On utilise 4 moles d'ammoniac et 5 moles de difluor. Exprimez les masses des quatre constituants du système en fonction de la masse de HF formée à un instant quelconque. Déterminez les masses des trois autres constituants lorsqu'il reste $3,5 \mathrm{~mol}$ de difluor.

On réalise la réaction dont l'équation stœchiométrique s'écrit : $2 \mathrm{NH}_3+5 \mathrm{~F}_2$ $=\mathrm{N}_2 \mathrm{~F}_4+6 \mathrm{HF}$. On utilise 4 moles d'ammoniac et 5 moles de difluor. Exprimez les masses des quatre constituants du système en fonction de la masse de HF formée à un instant quelconque.
Déterminez les masses des trois autres constituants lorsqu'il reste $3,5 \mathrm{~mol}$ de difluor.

Key Concepts

Mole-to-Mass Conversions

Mole-to-mass conversions are fundamental in chemistry for translating the number of moles of a substance into mass using its molar mass. This conversion is necessary because practical laboratory measurements are often made in mass, thus linking the theoretical stoichiometric calculations with real-world experimental data.

Reaction Extent

Reaction extent is a concept used to measure the progress of a chemical reaction, often represented by a variable that tracks the moles of reactants consumed or products formed. This allows for the expression of the amounts of all species in the system as functions of a single variable, which is useful for both theoretical analysis and practical calculations.

Stoichiometry

Stoichiometry is the study of quantitative relationships between the amounts of reactants and products in a chemical reaction. By using the balanced chemical equation, one can determine the proportionate amounts (in moles) that react or are produced, ensuring the law of conservation of mass is satisfied.

Limiting Reactant

The limiting reactant is the substance that is completely consumed first in a chemical reaction, thereby limiting the amount of products that can be formed. Determining the limiting reactant is essential in stoichiometric calculations because it directly influences the maximum yield of the desired products.

Transcript

00:01 Today we have a reaction of ammonia and fluorine and a few questions and answer about that.

00:07 Some stoichiometric questions and problems.

00:10 Intervalating different substances in here, interpreting them in terms of moles or mass or virtually anything.

00:19 Let's see what we have.

00:21 The first part here, question is to figure out if we want to make four moles of hydrogen fluoride, how many moles of the ammonia and h3 we would need and how much of the fluorine we need.

00:36 So these are all that would be a classic mole -mole calculation.

00:41 So we're just looking at really these subscript or coefficients here.

00:47 Coections would be the number of moles of each substance.

00:52 All right.

00:52 So simple conversion.

00:55 I'm going to take my six moles of hf and put it in the, denominator, omitting the unit mole here to make things a little bit easier.

01:06 So the reason that works is because you want to convert it.

01:10 So you want to remove that preceding unit.

01:12 All right.

01:13 So we're trying to figure out here.

01:14 I'm going to do the five fluorines, five moles of fluorine.

01:20 I'm going to do fluorine first here in this example.