At equilibrium, what is the hydrogen-ion concentration if the acid dissociation constant is 0.000 001 and the acid concentration is 0.01M?

Question

aaronq · Answer

HA <-> H+ + A-

Ka=[H+][A-]/[HA]

[H+]=[A-]=x

Ka=x^2/[HA]

anonymous · Answer

what does H stand for?

anonymous · Answer

or is it the answer?

aaronq · Answer

[H+] = would be be hydrogen cation concentration

anonymous · Answer

oh A stands for Acid?

aaronq · Answer

which is what you are looking for, just plug in your values into that last equation and solve for x

anonymous · Answer

can you help me with that?

aaronq · Answer

HA is any acid, A- is the conjugate base

aaronq · Answer

Ka=x^2/[HA]

Ka=0.000 001 

 [HA]= 0.01M

anonymous · Answer

ok itd be like  0.000 001= x^2/ 0.1?

anonymous · Answer

@Festinger

festinger · Answer

yes.

anonymous · Answer

ok then what

anonymous · Answer

do I move 0.1 to 0.000 001 and add them?

festinger · Answer

$$ 0.000 001= \frac{x^{2}}{0.1}$$
$$ 0.000 001*0.1 = x^{2}$$

anonymous · Answer

ok itd be 0.00000001^2?

anonymous · Answer

@Festinger

festinger · Answer

You need to brush up on your algebra.

$$0.000 001*0.1 = x^{2}$$$$0.000 000 1 = x^{2}$$$$x=\sqrt{0. 000 000 1}$$ pH is defined as -log[H]. Thus:
$$-log[H]=-log x = 3.5$$