Chapter 17, Problem 17.30UKC

(a)

Interpretation Introduction

Interpretation:

The reason for using the terms pyruvate and lactate rather than pyruvic acid and lactic acid at $pH=7.4$ has to be explained.

Concept Introduction:

Carboxylic acid: One $-OH$ group is attached to the carbonyl carbon atom of the compound. It is represented as $RCOOH$

Carboxylate anion: They are anions formed when hydrogen atom is removed from the $-COOH$ group of carboxylic acid. It forms an equilibrium with carboxylic acid in an aqueous solution.

Answer to Problem 17.30UKC

At $pH=7.4$, pyruvic acid and lactic acid exist as anions(pyruvate and lactate)

Explanation of Solution

Carboxylate anions are anions formed when hydrogen atom is removed from the $-COOH$ group of carboxylic acid. It forms an equilibrium with carboxylic acid in an aqueous solution.

At $pH=7.4$, pyruvic acid and lactic acid exist as anions where hydrogen atom is removed from the $-COOH$ group.

Therefore,

At $pH=7.4$ pyruvate and lactate exist.

(b)

Interpretation Introduction

Interpretation:

The structures acid altered to create pyruvic and lactic acid has to be drawn.

Concept Introduction:

Carboxylic acid: One $-OH$ group is attached to the carbonyl carbon atom of the compound. It is represented as $RCOOH$

Carboxylate anion: They are anions formed when hydrogen atom is removed from the $-COOH$ group of carboxylic acid. It forms an equilibrium with carboxylic acid in an aqueous solution.

Answer to Problem 17.30UKC

The altered structure is

Explanation of Solution

Carboxylate anions are anions formed when hydrogen atom is removed from the $-COOH$ group of carboxylic acid. It forms an equilibrium with carboxylic acid in an aqueous solution.

To alter the structures of pyruvate and lactate to create pyruvic acid and lactic acid, one hydrogen atom is added to the $-CO{O}^{-}$ group.

Therefore,

The structures acid altered to create pyruvic and lactic acid are,

(c)

Interpretation Introduction

Interpretation:

The hydrogen bonding in pyruvate and lactate has to be drawn. The expected difference in the solubility of pyruvate and lactate in water has to be explained.

Concept Introduction:

Solubility: The maximum quantity of a solute which can be dissolved at a particular amount of solvent in a certain temperature.

Carboxylic acid: One $-OH$ group is attached to the carbonyl carbon atom of the compound. It is represented as $RCOOH$

Carboxylate anion: They are anions formed when hydrogen atom is removed from the $-COOH$ group of carboxylic acid. It forms an equilibrium with carboxylic acid in an aqueous solution.

Hydrogen bonding is a type of dipole-dipole interaction of molecules when the hydrogen is bonded to strong electronegative atom in the molecules.

Answer to Problem 17.30UKC

• The solubilities of pyruvate and lactate in water is similar.
• Hydrogen bonding in pyruvate,

• Hydrogen bonding in lactate,

Explanation of Solution

Hydrogen bonding is a type of dipole-dipole interaction of molecules when the hydrogen is bonded to strong electronegative atom in the molecules.

• The oxygen atom in the $-CO{O}^{-}$ group of pyruvate and lactate forms hydrogen bond with the hydrogen atom of water molecule.
• The hydrogen atom in the $-OH$ group present in the lactate forms hydrogen bonding with oxygen atom of water molecule whereas oxygen atom on the carbonyl carbon present in the pyruvate forms hydrogen bonding with hydrogen atom of water molecule
• Since both pyruvate and lactate can form hydrogen bond with water molecule, they are soluble in water. The solubilities of pyruvate and lactate in water is similar.

Hydrogen bonding in pyruvate,

Hydrogen bonding in lactate,