Calculate the percent ionization of 0.140 M lactic acid in a solution containing 8.5×10−3 M sodium lactate.
Call lactic acid HL and sodium lactate NaL.
..........HL ==> H^+ + L^-
I.........0.140...0...0.0085
C.........-x......x.....x
E.......0140-x....x...0.0085+x
Substitute into the Ka expression for HL and solve for x = (H^+).It may be necessary to solve a quadratic.
Then %ion = [(H^+)/0.140]*100 = ?
To calculate the percent ionization of lactic acid in a solution containing sodium lactate, we need to know the Ka (acid dissociation constant) of lactic acid. The Ka expression for lactic acid is as follows:
Ka = [H+][C3H5O3-]/[C3H6O3]
First, we need to determine the initial concentration of lactic acid ([C3H6O3]). Since it is given that the initial concentration of sodium lactate is 8.5×10^−3 M, and assuming strong electrolyte dissociation, we can consider the initial concentration of lactate ion ([C3H5O3-]) to also be 8.5×10^−3 M.
Next, we need to calculate the equilibrium concentration of lactic acid and lactate ion using the given information and the Ka value. Assuming x is the amount of ionization, we can write the following expression for the concentrations at equilibrium:
[C3H6O3] = 0.140 M - x
[C3H5O3-] = 8.5×10^−3 M + x
[H+] = x
Substituting these values into the Ka expression, we get:
Ka = x * (8.5×10^−3 + x) / (0.140 - x)
Since the percent ionization is the ratio of the ionization to the initial concentration of the acid, we can approximate percentage ionization as x / 0.140 * 100.
To solve for x, we can use an iterative method or simplify the expression and solve for x numerically using a calculator or software. After finding the value of x, we can substitute it into the percent ionization formula to get the final result.
To calculate the percent ionization of lactic acid, we need to first understand the concept of ionization and its relationship with dissociation constant.
The ionization of an acid refers to the process in which it dissociates or breaks apart into ions when it dissolves in water. In the case of lactic acid, it can dissociate into the lactic acid anion (CH3CH(OH)COO-) and a hydrogen ion (H+). The equilibrium equation for this dissociation can be represented as:
CH3CH(OH)COOH ⇌ CH3CH(OH)COO- + H+
The extent to which an acid dissociates, or ionizes, is given by its dissociation constant (Ka). For lactic acid, the Ka is a constant that represents the equilibrium expression for the dissociation of the acid.
The dissociation constant (Ka) for lactic acid can be calculated using the concentrations of the products and reactant involved in the equilibrium expression. In this case, we can take the initial concentration of lactic acid (0.140 M) as the "reactant" concentration, and the equilibrium concentration of the lactic acid anion (CH3CH(OH)COO-) as the "product" concentration. However, it is important to note that the hydrogen ion (H+) concentration is not included in the expression, as it is typically very small and can be assumed to be negligible compared to the concentration of lactic acid.
Next, we need to determine the equilibrium concentration of the lactic acid anion (CH3CH(OH)COO-). This can be done by using the initial concentration of sodium lactate (8.5×10−3 M), as it dissociates into the lactic acid anion and sodium ion in solution. Since the concentration of the lactic acid anion is equal to the concentration of sodium lactate (as it completely dissociates), we can substitute the concentration of sodium lactate into the equilibrium expression.
To summarize the steps to calculate the percent ionization of lactic acid:
1. Calculate the dissociation constant (Ka) using the initial concentration of lactic acid (0.140 M).
2. Determine the equilibrium concentration of the lactic acid anion (CH3CH(OH)COO-) using the concentration of sodium lactate (8.5×10−3 M).
3. Use the dissociation constant and equilibrium concentration of the lactic acid anion in the equation to calculate the percent ionization.
Please note that the percent ionization is calculated by dividing the equilibrium concentration of the lactic acid anion by the initial concentration of lactic acid, and then multiplying by 100 to get a percentage.