A 0.0500 L solution of a 0.1000 M solution of a weak acid, HY. Ka = 1.80 x 10^-8. The solution is titrated with 0.1000 M NaOH. The pH at the equivalence point is approximately 10.20
A. Find the net ionic equation
B. Determine the pH of the original weak acid solution. (before the titration took place = initial pH)
A. You want the net ionic equation FOR WHAT? THE TITRATION? THE IONIZATION OF HY? THE HYDROLYSIS OF HY?
B. ............HY + H2O ==> H3O^+ + Y^
I................0.1......................0.............0
C................-x........................x..............x
E.............0.1- x.....................x...............x
Ka = (H^+)(Y^-)/(HY)
1.8E-8 = (x)(x)/(0.1-x)
Solve for x = (H3O^+) and convert to pH.
Thank you for your help on B !
The net ionic equation is for the titration
The molecular equation for the titration is as follows:
HY(aq) + NaOH(aq) ==> NaY(aq) + H2O(l)
Net ionic equation is as follows:
HY(aq) + OH^-(aq) --> Y^-(aq) + H2O(l)
A. To find the net ionic equation, we first need to determine the reaction that occurs between the weak acid, HY, and the strong base, NaOH. The reaction can be represented as follows:
HY + NaOH → H2O + NaY
In this net ionic equation, HY (the weak acid) loses a proton (H+) to form water (H2O), and NaOH (the strong base) donates a hydroxide ion (OH-) to form NaY (the salt). Please note that HY and NaY are typically written in their dissociated ionic form in solution.
B. To determine the pH of the original weak acid solution (before the titration took place), we need to consider the dissociation of the weak acid. The equation for the dissociation of the weak acid, HY, can be written as follows:
HY ⇌ H+ + Y-
The Ka value given (1.80 x 10^-8) represents the acidity constant, which is a measure of the degree of dissociation of the weak acid. It can be used to calculate the concentration of H+ ions in the solution at equilibrium.
To find the pH of the weak acid solution, we need to use the equation:
pH = -log[H+]
Given that the initial concentration of HY is 0.1000 M in a 0.0500 L solution, we can assume that the concentration of H+ will be very small compared to the concentration of HY due to its weak acidity. Therefore, we can approximate the concentration of H+ ions to be equal to the concentration of the weak acid, HY, at the beginning of the titration.
Substituting the values into the equation:
pH = -log(0.1000) = 1
Therefore, the initial pH of the weak acid solution is approximately 1.