Formic acid has a concentration of 0.1M and Kais 1.77 x 10-4. What is ...
The dissociation constant K = [H+][HCOO–]/[HCOOH] = x2/0.1 – x = 1.77 x 10-4; x = [H+] = 0.0042M. The percent of dissociation is x/0.1 = (0.042M)100% = 4.2. Therefore the value of degree of dissociation is 4.2
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Formic acid has a concentration of 0.1M and Kais 1.77 x 10-4. What is ...
To find the value of the degree of dissociation, we need to use the equilibrium constant expression for the dissociation of formic acid. Formic acid (HCOOH) dissociates into hydrogen ions (H+) and formate ions (HCOO-).
The balanced chemical equation for the dissociation of formic acid is:
HCOOH ⇌ H+ + HCOO-
The equilibrium constant expression for this reaction is given by:
K = [H+][HCOO-]/[HCOOH]
Given that the concentration of formic acid (HCOOH) is 0.1 M and K is 1.77 x 10^-4, we can substitute these values into the equilibrium constant expression:
1.77 x 10^-4 = [H+][HCOO-]/0.1
Now, let's assume that the degree of dissociation of formic acid is x. This means that at equilibrium, the concentration of hydrogen ions ([H+]) and formate ions ([HCOO-]) will be x, and the concentration of undissociated formic acid ([HCOOH]) will be (0.1 - x).
Substituting these values into the equilibrium constant expression, we get:
1.77 x 10^-4 = x * x / (0.1 - x)
Now, we can solve this equation to find the value of x, which represents the degree of dissociation.
By solving this equation, we find that x is approximately 0.042 or 4.2%.
Therefore, the correct answer is option B: 4.2.