The ionization constant of lactic acid, CH3 CH(OH) CO2 H , an acid found in the blood after stre

step 1 lactic acid is 90 .078 gram per mole. The number of mole of nova cane equivalent to 20 gram of l

The ionization constant of lactic acid, CH3 CH(OH) CO2 H ,...

The ionization constant of lactic acid, $\mathrm{CH}_{3} \mathrm{CH}(\mathrm{OH}) \mathrm{CO}_{2} \mathrm{H}$ , an acid found in the blood after strenuous exercise, is $1.36 \times 10^{-4} .$ If 20.0 g of lactic acid is used to make a solution with a volume of 1.00 $\mathrm{L}$ , what is the concentration of hydronium ion in the solution?

Key Concepts

Acid Dissociation Constant (Ka)

The acid dissociation constant, Ka, is a quantitative measure of the strength of a weak acid in solution. It expresses the equilibrium concentration ratio of the dissociated ions to the undissociated acid. In weak acids, only a small fraction of the acid molecules ionize, and Ka allows us to calculate how much acid will donate a proton in a solution to form hydronium ions.

Equilibrium in Weak Acid Solutions

In weak acid solutions, the acid partially ionizes, establishing an equilibrium between the undissociated acid and the ions produced. Understanding this equilibrium involves writing the dissociation reaction and the corresponding equilibrium constant expression, which is crucial for determining the concentration of hydronium ions in the solution.

Molarity and Stoichiometric Calculations

Molarity is the concentration of a solute in a solution, defined as the number of moles of solute divided by the volume of the solution in liters. Converting a given mass of acid to moles using its molar mass, and then finding its molarity, is an essential step in connecting the initial concentration of the acid to the extent of its ionization.

Approximations in Equilibrium Calculations

When solving equilibrium problems for weak acids, it is common to use approximations assuming that the change in concentration due to ionization is small compared to the initial concentration. This simplifies the algebraic manipulation of the equilibrium expression and is justified when the Ka value is very small relative to the initial concentration of the acid.

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