## Which is not a way to express the hydroxide and hydronium ion concentrations in pure water at 25°C? A.) pH of 7 B.)1.0 x 1

Question

Which is not a way to express the hydroxide and hydronium ion concentrations in pure water at 25°C?

A.) pH of 7
B.)1.0 x 107 M
C.)1.0 x 10-7 M

in progress 0

1. Here the word pure water means that there is nothing present in water only and only 100 % water 🙂 .

As we know that water can dissociate producing Hu207a (Hu2083Ou207a) and OHu207b as shown below,
Hu2082O u2194 Hu207a + OHu207b
or,
Hu2082O + Hu2082Ou2194 Hu2083Ou207a + OHu207b
Now,
The amount of Hu207a and OHu207b are very small in pure water and their concentration is as,
[Hu207a] = 1x 10u207bu2077 M (Option C is correct)

[OHu207b] = 1 x 10u207bu2077 M,

Taking antilog of [Hu207a],
-log [Hu207a] = pH

-log [1 x 10u207bu2077] = pH

pH = 7 (Option A is correct)
But,
Option B (i.e. 1.0x 10u2077 M) concentration is incorrect because it is very high concentration both for Hu207a ions ( making it acidic) and for OHu207b ions (making it basic).