Given the following data NH3(g)...

Given the following data $$ \begin{array}{ll} \mathrm{NH}_{3}(g) \longrightarrow \frac{1}{2} \mathrm{~N}_{2}(g)+\frac{3}{2} \mathrm{H}_{2}(g) & \Delta H=46 \mathrm{~kJ} \\ 2 \mathrm{H}_{2}(g)+\mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{H}_{2} \mathrm{O}(g) & \Delta H=-484 \mathrm{~kJ} \end{array} $$ calculate $\Delta H$ for the reaction $$ 2 \mathrm{~N}_{2}(\mathrm{~g})+6 \mathrm{H}_{2} \mathrm{O}(g) \longrightarrow 3 \mathrm{O}_{2}(g)+4 \mathrm{NH}_{3}(g) $$ On the basis of the enthalpy change, is this a useful reaction for the synthesis of ammonia?

Given the following data
$$
\begin{array}{ll}
\mathrm{NH}_{3}(g) \longrightarrow \frac{1}{2} \mathrm{~N}_{2}(g)+\frac{3}{2} \mathrm{H}_{2}(g) & \Delta H=46 \mathrm{~kJ} \\
2 \mathrm{H}_{2}(g)+\mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{H}_{2} \mathrm{O}(g) & \Delta H=-484 \mathrm{~kJ}
\end{array}
$$
calculate $\Delta H$ for the reaction
$$
2 \mathrm{~N}_{2}(\mathrm{~g})+6 \mathrm{H}_{2} \mathrm{O}(g) \longrightarrow 3 \mathrm{O}_{2}(g)+4 \mathrm{NH}_{3}(g)
$$
On the basis of the enthalpy change, is this a useful reaction for the synthesis of ammonia?

Key Concepts

Thermodynamic Feasibility in Synthesis

Assessing the thermodynamic feasibility of a chemical synthesis involves analyzing the overall enthalpy change of the reaction. A highly endothermic process may require significant energy input, making it less suitable for efficient production, while exothermic operations are usually more advantageous.

Endothermic vs. Exothermic Reactions

This concept distinguishes reactions that absorb heat from those that release heat. Understanding which category a reaction falls into is vital when evaluating its practicality for industrial synthesis, since exothermic reactions are generally preferred for their energy efficiency.

Reaction Enthalpy

Reaction enthalpy is the measure of the heat change that occurs during a chemical reaction at constant pressure. It is a quantitative measure that indicates whether a reaction absorbs (endothermic) or releases (exothermic) heat, helping chemists assess the energy requirements or outputs of a process.

Hess's Law

Hess's Law allows the calculation of the enthalpy change for an overall reaction by summing the enthalpy changes of individual steps or related reactions. This principle is crucial because it shows that the total enthalpy change is independent of the reaction pathway and only depends on the initial and final states.

Stoichiometry in Thermochemical Calculations

Stoichiometry in thermochemical calculations involves using the mole ratios of reactants and products to appropriately scale and combine chemical equations. This ensures that the calculated overall enthalpy change correctly reflects the proportions of substances involved in the target reaction.

Transcript

00:01 We are given the following two chemical equations.

00:13 Actually, i like to do my target first.

00:15 I'm going to write the target first.

00:18 My target reaction is 2n2 plus 6h2, yields 302 plus 4nh3.

00:44 And that's our target.

00:46 And our given reactions are nh3.

00:52 And we have one half n2 plus 3 over 2 h2.

01:03 I'm given my heat of 46 kilojoules.

01:08 My second reaction is 2h2 plus o2 yields 2 h2.

01:20 I don't often see that one written like that.

01:31 Okay.

01:34 So let's, and then we're asked to respond to, is this reaction a useful, useful for the synthesis of ammonia? and we're going to be looking for exothermic or not very endothermic.

02:15 If it's very endothermic, then it won't work well.

02:21 Let's begin.

02:23 I'm going to go with a little bit darker blue.

02:25 Perfect.

02:26 So what we're going to do is rearrange these reactions.

02:30 Easy peasy.

02:32 I'm just looking at them now to see what's good.

02:37 I'm going to go with a super light green here and see.

02:40 I can see that i have nh3 right here and right here...

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