Question

What pH level is considered to be acidic and basic?

Answer 1

In aqueous solution, for `pH` `<` `7`, an acidic solution is specified...........

Explanation:

And for `pH` `>` `7`, a basic solution is described. For `pH=7`, we describe a NEUTRAL solution.

But what is `pH`?

`pH` is a measure of the concentration of hydronium ion, `[H_3O^+]`, i.e. `pH=-log_10[H_3O^+]`. Equivalently, `pH=-log_10[H_^+]`. `H_3O^+` and `H^+` are used to represent the `"acidium ion"` in aqueous solution.

The use of logarithms is a bit old-fashioned, but back in the day A level students used to used log tables, before the advent of cheap electronic calculators.

For water:

`pH` `=` `-log_10[H_3O^+]`

`pOH` `=` `-log_10[HO^-]`

Now `K_w` `=` `[H_3O^+][HO^-]` `=` `10^(-14)" at 298K"`.

Thus `-log_10K_w=-log_10[H_3O^+] -log_10[HO^-]`

`=-log_10(10^-14)` `=` `+14`

And thus `pOH+pH=14` under standard conditions.

You should review the logarithmic function if you have any problem with this treatment. You should review it anyway, because I might have made a mistake.