Pure water is neutral. What is the appropriate justification for this?

Question

teddyiswatshecallsme · Answer

Choice A, neutral means the H+ ions equal the OH- ions, giving a pH of 7. The first choice is pretty much that exact definition

anonymous · Answer

@Teddyiswhatshecallsme where is choice A from?

anonymous · Answer

Yes, pure water is neutral because we have an equal concentration of $$H _{3}O ^{+} $$ and $$OH ^{-}$$ ions.

In fact water only very slightly ionizes, so  $$K _{w}$$ value is very very small$$= - 1 \times10^{-14}$$

Finding the equilibrium expression of water gives us $$Kw = [OH ^{-}][H3O ^{+}]$$
That is for the reaction:

$$H _{2}O + H _{2} O \leftarrow \rightarrow H _{3}O ^{+} + OH ^{-}$$

And  $$Kw = 1 \times 10 ^{-14}$$
And 
$$[OH ^{-}] = [H _{3} O ^{+}]$$ $$= 1 \times 10^{-7}$$

Finding pH= $$-\log ([H _{3} O ^{+}] )$$= $$-\log( 1 \times 10^{-7}) = 7$$

7 pH is neutral.

teddyiswatshecallsme · Answer

Just A. lolol

teddyiswatshecallsme · Answer

Multiple choice.