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Chemical reaction equations play a pivotal role in representing chemical changes and reactions. In the Ostwald process, we use these equations to describe how ammonia (\(\mathrm{NH_3}\)) is transformed into nitric acid (\(\mathrm{HNO_3}\)). Each step of the process has unique reactants and products that make up individual chemical equations.
Each equation reflects a conservation of mass through balanced reactants and products. This means the number of each type of atom on the reactant side is equal to the number on the product side. For instance, in our first equation, 4 moles of ammonia react with 5 moles of oxygen, yielding 4 moles of \(\mathrm{NO}\) and 6 moles of water vapor.

• First equation: \(4 \mathrm{NH}_3(g)+5 \mathrm{O}_2(g) \rightarrow 4 \mathrm{NO}(g)+6 \mathrm{H}_2 \mathrm{O}(g)\)
• Second equation: \(2 \mathrm{NO}(g)+\mathrm{O}_2(g) \rightarrow 2 \mathrm{NO}_2(g)\)
• Third equation: \(3 \mathrm{NO}_2(g)+\mathrm{H}_2 \mathrm{O}(l) \rightarrow 2 \mathrm{HNO}_3(aq)+\mathrm{NO}(g)\)

Combining these step-wise reactions gives a comprehensive understanding of the overall chemical process and helps us derive the molar ratios necessary for further calculations.

Molar mass calculation involves determining the mass of one mole of a chemical substance, using atomic masses from the periodic table. For complex molecules like nitric acid (\(\mathrm{HNO_3}\)), you sum the atomic masses of each constituent element multiplied by their respective coefficients in the chemical formula.
Here's how to calculate the molar mass of \(\mathrm{HNO_3}\):

• Find the atomic mass of each element: Hydrogen (H) is 1 g/mol, Nitrogen (N) is 14 g/mol, and Oxygen (O) is 16 g/mol.
• Apply the formula: \(M_{\mathrm{HNO_3}} = (1 \times 1) + (1 \times 14) + (3 \times 16)\).
• Add them together: \(M_{\mathrm{HNO_3}} = 1 + 14 + 48 = 63\) g/mol.

These individual atomic contributions culminate in the total molar mass, which is essential for converting between mass and moles in chemical reactions.

Understanding mass-mole conversions is essential for translating between physical measurements and chemical calculations. Converting mass to moles and vice versa relies on knowing the substance's molar mass.
For instance, in the Ostwald process, if we want to determine the number of moles of \(\mathrm{HNO_3}\) produced from 1,000,000 kg, we use the molar mass of \(\mathrm{HNO_3}\) determined earlier:

• Convert mass to grams: \(1,000,000 \times 10^3\) grams.
• Use the molar mass: \(n_{\mathrm{HNO_3}} = \frac{1,000,000,000}{63}\) moles.

Similarly, the mole concept allows us to find the mass of \(\mathrm{NH_3}\) needed. With the stoichiometric relationships from the balanced equations, the conversion goes as follows:

• Using the ratio from the net equation (4 moles of \(\mathrm{NH_3}\) produce 2 moles of \(\mathrm{HNO_3}\)), find moles of \(\mathrm{NH_3}\) required: \(n_{\mathrm{NH_3}} = 2 \times n_{\mathrm{HNO_3}}\).
• Convert to mass using \(M_{\mathrm{NH_3}}\): \(m_{\mathrm{NH_3}} = n_{\mathrm{NH_3}} \times M_{\mathrm{NH_3}}\).

Each conversion is grounded in the balanced equations and molar masses, weaving together the theoretical and practical aspects of chemical calculations effectively.