The ka of hydrofluoric acid (hf) at 25.0 degrees celsius is 6.8*10-4. what is the ph of a 0.15m aqueous solution of hf? the ka of hydrofluoric acid (hf) at 25.0 c is 6.8 x10-4. what is the ph of a 0.15 m aqueous 8) solution of hf? a) 4.60 b) 0.82 c)3.64 d) 1.17 e) 2.00

E) 2.00

Explanation:

Step 1. Calculate the concentration of hydronium ion

We can use an ICE table to organize the calculations.

                      HF + H₂O ⇌ H₃O⁺ + F⁻

I/mol·L⁻¹:       0.15                   0       0

C/mol·L⁻¹:      -x                     +x      +x

E/mol·L⁻¹:   0.15 - x                 x        x

Step 2. Calculate the pH

substituting a hydrogen atom with a halogen in a hydrocarbon:

- the single bond remains single. a is wrong.

- the bond with hydrogen is as strong as with a halogen. c is wrong

- a hydrocarbon is saturated if there is no double bond. we do not know that so d is wrong.

- carbon will always have four valence electrons. e is wrong.

by elimination, the correct answer is b. the boiling point of the new compound increases.

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