I don’t like remembering a formula without knowing exactly how it happens, but when I was doing Chemistry A-Level last year the method we was taught was too complex, especially since you had to remember the formulas to work it out that way too.
pH of a Weak Acid = -log(√Ka c)
Where ‘Ka’ is the dissociation constant, and ‘c’ is concentration
Where ‘Ka’ is the dissociation constant, and ‘c’ is concentration
Some methods involve solving a quadratic, but this one skips it. In all of the cases where I tried this, the result using the quadratic method is about 0.5% larger than this formula will give you. It’s barely any different, so you probably don’t need to worry about it.