/sci/ - Science & Math

Any chemists around?

This seems extremely simple, still, I can't seem to be able to solve it.

I tried using:


<span class="math">pH = pK_a + log \frac{[A^{-}]}{[HA]}[/spoiler]
as <span class="math">pH=pK_a[/spoiler]
<span class="math">log \frac{[A^{-}]}{[HA]} = 0[/spoiler]
<span class="math">\frac{[A^{-}]}{[HA]} = 1[/spoiler]
<span class="math">[A^{-}] = [HA][/spoiler]


So I've written the equilibrium reaction: (which I had to google, how would I know it's not a base?)

<span class="math">CH_3COOH + H_2O \rightleftharpoons H_3O^+ + CH3COO^-[/spoiler]


So, I tried finding <span class="math">K_a[/spoiler]

<span class="math">K_a = \frac{[CH_3COO^-][H_3O^+]}{[CH_3COOH]}[/spoiler]
And as I discovered <span class="math">[A^{-}]} = {[HA][/spoiler]


<span class="math">K_a = \frac{[x][H_3O^+]}{[x]}[/spoiler]
<span class="math">K_a = [H^+][/spoiler]
<span class="math">pK_a = pH[/spoiler]

See? I've been redundant during the entire time and couldn't find an answer...

Could someone, please, point the simplest way of solving this? Thank you.

Any chemists around?

This seems extremely simple, still, I can't seem to be able to solve it.

I tried using:


<span class="math">pH = pK_a + log \frac{[A^{-}]}{[HA]}[/spoiler]
as <span class="math">pH=pK_a[/spoiler]
<span class="math">log \frac{[A^{-}]}{[HA]} = 0[/spoiler]
<span class="math">\frac{[A^{-}]}{[HA]} = 1[/spoiler]
<span class="math">[A^{-}] = [HA][/spoiler]


So I've written the equilibrium reaction: (which I had to google, how would I know it's not a base?)

<span class="math">CH_3COOH + H_2O \rightleftharpoons H_3O^+ + CH3COO^-[/spoiler]


So, I tried finding <span class="math">K_a

<span class="math">K_a = \frac{[CH_3COO^-][H_3O^+]}{[CH_3COOH]}[/spoiler]
And as I discovered <span class="math">[A^{-}]} = {[HA][/spoiler]


<span class="math">K_a = \frac{[x][H_3O^+]}{[x]}[/spoiler]
<span class="math">K_a = [H^+][/spoiler]
<span class="math">pK_a = pH[/spoiler]

See? I've been redundant during the entire time and couldn't find an answer...

Could someone, please, point the simplest way of solving this? Thank you.

Any chemists around?

This seems extremely simple, still, I can't seem to be able to solve it.

I tried using:

<span class="math">
pH = pK_a + log \frac{[A^{-}]}{[HA]}
[/spoiler]
as <span class="math">pH=pK_a[/spoiler]
<span class="math">
log \frac{[A^{-}]}{[HA]} = 0
\frac{[A^{-}]}{[HA]} = 1
[A^{-}]} = {[HA]
[/spoiler]

So I've written the equilibrium reaction: (which I had to google, how would I know it's not a base?)

<span class="math">
CH_3COOH + H_2O \rightleftharpoons H_3O^+ + CH3COO^-
[/spoiler]

So, I tried finding <span class="math">K_a[/spoiler]

<span class="math">K_a = \frac{[CH_3COO^-][H_3O^+]}{[CH_3COOH]}[/spoiler]
And as I discovered <span class="math">[A^{-}]} = {[HA][/spoiler] :

<span class="math">
K_a = \frac{[x][H_3O^+]}{[x]}
K_a = [H^+]
pK_a = pH
[/spoiler]

See? I've been redundant during the entire time and couldn't find an answer...

Could someone, please, point the simplest way of solving this? Thank you.