Acidic vs. Basic Solution

[Nigah Fatima]

I understand that acidic solutions have more hydronium ions, while basic solutions have more hydroxide ions. However, my confusion is how do logarithms play a role in this as to how we decide how many hydronium ions versus how many hydroxide ions are there. In lecture, I remember seeing that the concentrations of the hydronium and hydroxide ions written as logarithms is a more convenient method. If someone can explain this, I would greatly appreciate it.

[Jaden Nguyen 2A]

The pH scale is logarithmic because when using the -log for pH, it's the -log10(Hydronium Concentration). When going down the pH scale, each transition is a difference of 10x. The pH scale was made to be logarithmic because of what Dr. Lavelle said in class: simplicity. Instead of referring to hydronium concentration in terms of molarity, we use pH instead.

[Shivani Sakthi 1l]

Hello! You are absolutely correct when you say that the PH scale is used to express the relative acidity and basic nature of solutions for convenience. Let us put this concept into motion through an example. Say you have one solution that has a concentration of 10^-6 H3O+ ions. Another solution has a concentration of 10^-5 H3O+. Off of first look, it may be difficult to decipher which of these solutions may be more acidic and basic. By using the PH scale that relies on logarithms, we get a more clear answer.

PH= -log10[10^-6]=6
PH=-log10[10^-5]=5

Since the second solution has a lower PH than the first solution, we know that it is more acidic. This makes sense because the second solution has more hydronium ions. However, it is more convenient to express a single PH number than to express the concentration of hydronium ions to assess acidity. Furthermore, the one value difference between the PH of the first solution and the PH of the second solution shows that the second solution is 10 times more acidic than the first solution. This is far more convenient to assess with the logarithmic PH scale.

[205678283]

Hi! the logarithm function is just used for the formula to calculate the value of pH or pOH. You can look at this chart for a better visual!

[AJackman]

Because when describing the actual concentration of H+ or OH- in a solution, the numbers can get ridiculously small/large. Taking the negative log puts it on a neat 1-14 scale that's easier to deal with and compare.