K-value missing in acid-base problem?

[alingy2]

What initial concentration of HF (aq) in water would give a solution with a pH = 1.5?

I think the K value is missing... How could we solve this problem?

 

[majormaaz]

What initial concentration of HF (aq) in water would give a solution with a pH = 1.5?

I think the K value is missing... How could we solve this problem?

Hey there!
I'm sure you know the K of water - what you're looking for is the K_a value of HF. Have you not been given the value?

 

[Borek]

Is there a table of Ka values in your book?