[3mpathogens]

My understanding:
pH = -log[H+] applies to all acids. For strong acids, the molar concentration of the acid itself can be used in place of [H+] given that strong acids dissociate completely (assuming we're using H₂O. For weak acids, however, [H+] must be calculated.

Is this correct? Any nuances to add in? Thanks in advance.

[Borek]

Is this correct?

As a first approximation - yes.

Any nuances to add in?

Plenty

Even some strong acids are not as strong as it is commonly assumed (like nitric acid with pKa=-1), but there is another, much more important problem. Observed/measured pH is not just log of H⁺ concentration, it is log of H⁺ activity - for diluted solutions these are almost identical, the higher the concentration, the higher the ionic strength of the solution, the larger the difference. Google Debye-Huckel theory for a starting point.

[3mpathogens]

Is this correct?

As a first approximation - yes.

Any nuances to add in?

Plenty

Even some strong acids are not as strong as it is commonly assumed (like nitric acid with pKa=-1), but there is another, much more important problem. Observed/measured pH is not just log of H⁺ concentration, it is log of H⁺ activity - for diluted solutions these are almost identical, the higher the concentration, the higher the ionic strength of the solution, the larger the difference. Google Debye-Huckel theory for a starting point.

Thanks so much!