When heated, lithium reacts with nitrogen to form lithium...

When heated, lithium reacts with nitrogen to form lithium nitride: $$6 \mathrm{Li}(s)+\mathrm{N}_{2}(g) \longrightarrow 2 \mathrm{Li}_{3} \mathrm{N}(s)$$ What is the theoretical yield of $L$ is $N$ in grams when 12.3 g of $L$ i are heated with $33.6 \mathrm{g}$ of $\mathrm{N}_{2}$ ? If the actual yield of $\mathrm{Li}_{3} \mathrm{N}$ is $5.89 \mathrm{g}$, what is the percent yield of the reaction?

When heated, lithium reacts with nitrogen to form lithium nitride:
$$6 \mathrm{Li}(s)+\mathrm{N}_{2}(g) \longrightarrow 2 \mathrm{Li}_{3} \mathrm{N}(s)$$
What is the theoretical yield of $L$ is $N$ in grams when 12.3 g of $L$ i are heated with $33.6 \mathrm{g}$ of $\mathrm{N}_{2}$ ? If the actual yield of $\mathrm{Li}_{3} \mathrm{N}$ is $5.89 \mathrm{g}$, what is the percent yield of the reaction?

Key Concepts

Molar Mass Calculation

Molar mass calculation involves determining the mass of one mole of a substance, which is crucial for converting between grams and moles. This conversion is necessary for stoichiometric calculations when using a balanced equation to relate reactants to products.

Percent Yield

Percent yield is a measure of the efficiency of a chemical reaction. It compares the actual yield obtained from an experiment to the theoretical yield, expressed as a percentage, and provides insight into the practical limitations and losses during the reaction.

Stoichiometry

Stoichiometry involves calculating the quantitative relationships between the reactants and products in a chemical reaction, as dictated by the balanced chemical equation. It allows the conversion of amounts (in moles or grams) between substances using mole ratios, and is fundamental to determining yields and reactant limitations.

Limiting Reactant

The limiting reactant is the substance that is completely consumed first in a reaction, determining the maximum amount of product that can be formed. Identifying the limiting reactant is essential for calculating the theoretical yield since it dictates the reaction's overall product formation capacity.

Theoretical Yield

The theoretical yield is the maximum amount of product that can be produced from a given amount of reactants, based on stoichiometric calculations from the balanced reaction. It represents the ideal output assuming perfect conditions and complete reaction of the limiting reactant.

Transcript

00:01 So for this problem, we have a reaction involving lithium and nitrogen, and we want to first find for part a, or for the first question, the theoretical yield of l -i -n, or l -i -3 -n.

00:13 So we know that the reaction that we're dealing with is the following.

00:23 So the first thing when we're going to try to find the theoretical yield of anything is we have to find the mole masses of all of our relevant substances.

00:32 So first for nitrogen, well, we have two nitrogen atoms, which is 14 .01.

00:42 So we get that our molar mass is 28 .02 grams per mole.

00:48 And then for la3n, well, for lithium, we have three of them, and they're each 6 .94 grams from mole.

00:57 And we add 14 .01 for the one nitrogen atom.

01:03 And when we multiply that out we'll get 34 .83 grams per mole.

01:11 And then finally lithium, singular element, is 6 .94.

01:16 If we look at the periodic table.

01:20 So now that we have the molar masses of all of our relevant compounds and elements, we want to find which is the limiting reactant.

01:28 Is it lithium or nitrogen gas? so then we can then find the theoretical yield of li3.

01:34 So let's first analyze the lithium.

01:39 So we know that we are given 12 .3 grams of lithium.

01:45 So given 12 .3 grams of lithium and 33 .6 grams of n2.

01:56 So let's first take our lithium and see how many moles of n2 are required to react with all of the lithium.

02:03 So we have 12 .3 grams of lithium.

02:09 We convert this to moles by dividing the molar mass.

02:16 And we take the multiple ratio.

02:18 Well, we see that in order to produce, or in order to react with one mole of nitrogen gas, we need six moles of lithium.

02:26 So the multiple ratio is 1 to 6 as such...

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