A weak acid HA is 1.0% dissociated in a 1.0 M solution. What would its percent dissociation be
in a 5.0 M solution?
...........HA ==> H^+ + A^-
...........1M......0....0
C.......-0.01...0.01..0.01
E........0.99....0.01..0.01
Ka = (H^+)(A^-)/(HA)
Substitute the above into Ka expression and solve for Ka. I think you should obtain about 1E-4 but that isn't exact.
Then.........HA ==> H^+ + A^-
I............5......0.....0
C............-x.....x.....x
E...........5-x.....x....x
Ka = (H^+)(A^-)/(HA)
about 1E-4 = (x)(x)/(5-x)
Solve for x and I get about 0.02 (you need to do it more accurately).
% ionization = (0.02/5)*100 =?
To determine the percent dissociation of a weak acid in a 5.0 M solution, we need to use the concept of the dissociation constant (Ka) and the equation for percent dissociation.
The percent dissociation of a weak acid is given by the equation:
percent dissociation = (concentration of dissociated species / initial concentration of acid) * 100
In this case, we know that the weak acid HA is 1.0% dissociated in a 1.0 M solution. Therefore, we can calculate the concentration of the dissociated species as follows:
concentration of dissociated species = (percent dissociation / 100) * initial concentration of acid
In the 1.0 M solution, the concentration of the dissociated species would be:
concentration of dissociated species = (1.0% / 100) * 1.0 M = 0.01 M
Now, let's calculate the percent dissociation in a 5.0 M solution using the same equation:
percent dissociation = (concentration of dissociated species / initial concentration of acid) * 100
To determine the concentration of the dissociated species in the 5.0 M solution, we can use the fact that the dissociation constant (Ka) remains constant for a given weak acid. Therefore, we can assume that the value of Ka is the same for both solutions.
Since the initial concentration of acid is different (1.0 M for the 1.0 M solution and 5.0 M for the 5.0 M solution), we need to calculate the new concentration of the dissociated species in the 5.0 M solution. We can use the following equation:
concentration of dissociated species = (concentration of dissociated species in 1.0 M solution) * (initial concentration of acid in 5.0 M solution) / (initial concentration of acid in 1.0 M solution)
Plugging in the values:
concentration of dissociated species = 0.01 M * 5.0 M / 1.0 M = 0.05 M
Finally, we can calculate the percent dissociation in the 5.0 M solution:
percent dissociation = (concentration of dissociated species / initial concentration of acid) * 100 = (0.05 M / 5.0 M) * 100 = 1.0%
Therefore, the percent dissociation of the weak acid HA in a 5.0 M solution would also be 1.0%.