Logarithms

[Rachel Chan 1B]

What did Professor Lavelle mean that it's more convenient to write [H3O+] and [OH-] as logarithms? Is it because there are logarithmic rules we can apply to make calculations easier? How would I write them as logarithms (an example would be great, if possible!)?

[Stephen_Kim_1D]

He just means that it's convenient to write their concentrations as -log[concentration], which is why we have the pH scale. If we have a H3O+ concentration of 1x10^-7 M, -log[10^-7] = -(-7) = 7, and it's more convenient to write 7 instead of 1x10^-7. That's why we say the pH of water is 7 rather than saying the concentration of H3O+ in water is 1x10^-7 M.

[Christina Gigoux 1D]

Writing these values as logs (as pH or pOH) is much easier because it is shorter and easier to compare values. For example [H3O+] = 1.7 x 10^-7 is much longer than 6.77 and comparing [H3O+] = 1.7 x 10^-7 and [H3O+] = 5.8 x 10^-8 is much more complicated than comparing pH of 6.77 and 7.24

[Diya Kar]

Professor Lavelle implied that it is easier to depict the concentrations of H30+ and OH- as logarithms as the log of both concentrations will equate to pH and pOH. A low pH and high pOH indicates acidic behavior. A high pH and low pOH indicates basic behavior. Thus, it is easier to visualize the behavior of a molecule based off its logarithmic value.

[briana lay 3c]

Hello!
I believe he said that because writing the actual concentrations would get tedious over time (imagine having to write "x10^n" over and over again!). Writing it in logarithmic form would just simplify things. Hope it helps!

[Crystal Ma 2J]

-log[H30+] if H30+ = 6.7x10^-7 would be 6.17 for example, which is easier to use in calculations than a long number such as 6.7x10^-7