One mole of aspartame (C14H18N2O5) reacts with two moles of water to produce one mole of
aspartic acid (C4H7NO4), one mole of methanol (CH3OH) and one mole of phenylalanine.

a. What is the molecular formula of phenylalanine?

b. What mass of phenylalanine is produced from 378 g of aspartame?

A. The molecular formula of phenylalanine is C₉H₁₁NO₂

B. The mass of phenylalanine, C₉H₁₁NO₂ produced from 378 g of aspartame is 212.14 g

A. Determination of the molecular formula of phenylalanine.

To obtain the molecular formula of phenylalanine, we shall write the balanced equation. This is given below

C₁₄H₁₈N₂O₅ + 2H₂O → C₄H₇NO₄ + CH₃OH + C₉H₁₁NO₂

Thus, the molecular formula of phenylalanine is C₉H₁₁NO₂

B. Determination of the mass of phenylalanine, C₉H₁₁NO₂ produced from 378 g of aspartame

C₁₄H₁₈N₂O₅ + 2H₂O → C₄H₇NO₄ + CH₃OH + C₉H₁₁NO₂

Molar mass of C₁₄H₁₈N₂O₅ = (14×12) + (18×1) + (14×2) + (16×5) = 294 g/mol

Mass of C₁₄H₁₈N₂O₅ from the balanced equation = 1 × 294 = 294 g

Molar mass of C₉H₁₁NO₂ = (9×12) + (11×1) + 14 + (16×2) = 165 g/mol

Mass of C₉H₁₁NO₂ from the balanced equation = 1 × 165 = 165 g

From the balanced equation above,

294 g of C₁₄H₁₈N₂O₅ reacted to produce 165 g of C₉H₁₁NO₂

Therefore,

378 g of C₁₄H₁₈N₂O₅ will react to produce = (378 × 165) / 294 = 212.14 g of C₉H₁₁NO₂

Thus, 212.14 g of C₉H₁₁NO₂ were obtained from the reaction.

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a. Molecular formula of phenylalanine → C₉H₁₁NO₂

b. 234.2 g of C₉H₁₁NO₂

Explanation:

Let's think the reaction:

C₁₄H₁₈N₂O₅  +  2H₂O →  CH₃OH  +  ‎C₉H₁₁NO₂ + C₄H₇NO₄

In order to work with this reaction, we assume that water is on excess.

Let's determine the moles of aspartame → molar mass = 294 g/mol

Moles = mass / molar mass → 378 g / 294 g/mol = 1.28 moles

As ratio is 1:1, 1 mol of aspartame can produce 1 mol of phenylalanine; therefore 1.28 moles of aspartame must produce 1.28 moles of phenylalanine.

Let's convert the moles to mass → molar mass C₉H₁₁NO₂ = 183 g/mol

Moles . molar mass = Mass → 1.28 mol . 183 g/mol = 234.2 g