[TheGreatDeath]

Hello, I'm having a few problems with this question.

If 535 mL of gaseous HCL, at 26.5ºC and 747 mmHg, is dissolved in enough water to prepare 625 mL of solution, what is the pH of this solution?

I partially understand what to do for this equation. Use the ideal gas law, PV = nRT, and solve for n. Then somehow use that to find the HCL concentration. Then use Kw = [H30][OH] = 1.0 x 10^-14 and find OH. Finally, use OH concentration to find pH. But each attempt to try to solve this, I am not getting the correct answer. The back of the book answer is, "pH= 1.466".

Thanks for reading, and for any helpful advice or solution.

[Borek]

1. To calculate concentration you just divide n by V.

2. No need to calculate OH^- concetration. See pH of strong acid (equation 7.6).

3. Hardly surprising, but the book answer looks correct

[TheGreatDeath]

Thanks, I'm not sure why I was struggling with this one. Probably typos in the calculator 

[enahs]

Thanks, I'm not sure why I was struggling with this one. Probably typos in the calculator 

You are probably using the wrong Gas Constant for the units with pressure in mmHG/Torr. Or you can convert your pressure units to kPa to use 8.314 L · kPa · K^-1 · mol^-1. Or many other options.
http://en.wikipedia.org/wiki/Gas_constant

The units on the left hand side of PV=nRT must cancel/equal the units on the right hand side. The gas constant does that, if you use the wrong gas constant for the units, that does not happen and your equation is invalid.


And your temp is in Kelvin, right?


Units units units!