Suppose that 85 mL of 0.4 M NaF and 50 mL of 0.4 M HCl are mixed.
What is the K for the dominant equilibrium in terms of Ka's, Kb's, Kw etc.?
Ka of HCl
1/Ka of HCl
Ka of HF
1/Ka of HF
Kb of F-
1/Kb of F-
Kb of Cl-
1/Kb of Cl-
Kw
1/Kw
There is no reaction.
millimols HCl = 0.4 x 50 = 20
millimols NaF = 85 x 9.4 = 34
.......F^- + H^+ ==> HF
I.....34.....0.......0
add.........20............
C....-20...-20.......+20
E.....14....0........20
Ka for the rxn = (HF)/(H^+)(F^-)
Doesn't that look like 1/Ka of HF to you. You could use the Henderson-Hasselbalch equation and calculate the pH of the solution.
To determine the K for the dominant equilibrium, we need to analyze the possible reactions that can occur in the given mixture and identify which one has a dominant equilibrium.
In this case, we have 85 mL of 0.4 M NaF and 50 mL of 0.4 M HCl. When these two solutions are mixed together, a neutralization reaction can occur between NaF and HCl:
NaF + HCl → NaCl + HF
In this reaction, NaF and HCl react to form NaCl (sodium chloride) and HF (hydrofluoric acid). The presence of HF indicates a possible dominant equilibrium involving HF.
The equilibrium expression for HF can be written as follows:
HF ↔ H+ + F-
The constant for this equilibrium is represented as K.
Now, let's consider the given options and determine their relevance to the dominant equilibrium:
1. Ka of HCl: This represents the acid dissociation constant for HCl, but it is not directly related to the dominant equilibrium involving HF.
2. 1/Ka of HCl: The reciprocal of the acid dissociation constant for HCl is also not directly related to the dominant equilibrium involving HF.
3. Ka of HF: This represents the acid dissociation constant for HF, which is directly related to the dominant equilibrium we are interested in.
4. 1/Ka of HF: The reciprocal of the acid dissociation constant for HF is directly related to the dominant equilibrium we are interested in.
5. Kb of F-: This represents the base dissociation constant for F-, which is not directly related to the dominant equilibrium involving HF.
6. 1/Kb of F-: The reciprocal of the base dissociation constant for F- is not directly related to the dominant equilibrium involving HF.
7. Kb of Cl-: This represents the base dissociation constant for Cl-, which is not directly related to the dominant equilibrium involving HF.
8. 1/Kb of Cl-: The reciprocal of the base dissociation constant for Cl- is not directly related to the dominant equilibrium involving HF.
9. Kw: This represents the ion product constant for water, which is not directly related to the dominant equilibrium involving HF.
10. 1/Kw: The reciprocal of the ion product constant for water is not directly related to the dominant equilibrium involving HF.
Based on the above analysis, the relevant option for the dominant equilibrium involving HF is "Ka of HF." The K for the dominant equilibrium in terms of Ka's is Ka of HF.
Therefore, the answer to the question is: The K for the dominant equilibrium in terms of Ka's is the Ka of HF.