Here's the question you clicked on:
valiyuh
Can someone please explain to me how calculate the ph of 0.003 M HCLplease?
\[pH= - \log_{10}([H^+])\] The pH is just the negative logarithm of the Hydrogen ion concentration. It's purely out of convenience since it's easier to talk about the pH rather than the really small number usually is. So what is concentration? It's literally just the number of hydrogen atoms per volume of liquid. We count them by using moles rather than just the direct number. But if you have say, 6 mols of Hydrogen you can just multiply that by 6.02x10^23 to get the actual number of atoms just like if you have 6 dozen eggs you can multiply that by 12 to get the actual number of eggs. Since you're given 0.003 M HCl that's a good sign, you don't have to calculate anything! M is the symbol for Molar which is just moles per Liter \[1 Molar = 1 \frac{moles}{Liter}\] Or written like this, same thing.\[1 M = 1 \frac{mol}{L}\] Since HCl is a Strong Acid it will dissociate completely, giving you 1 mol of H+ for every mol of HCl you have. Another strong acid such as H2SO4 will dissociate 2 mols of H+ for every mol of acid you have, so you would multiply by 2 in that case. So that being said, we really just plug the number in, and out comes our pH! \[pH=-\log_{10}(.003)\]