Concentration of OH in HCl

[brake4country]

Homework Statement

At 10 C, the concentration of OH in 1 M of HCl is approximately:

Answer: 3x10^15

Homework Equations

K_w=K_aK_b

The Attempt at a Solution

This answer throws me off. If we assume that HCl completely dissociates, we use the [H+] from the acid in the above equation:
1x10^-14 = 1 [OH]

I get 1 x 10^-14, not 3 x 10^-15. What am I missing here? Is my book wrong? Thanks.

 

[Borek]

See the table here: http://www.chembuddy.com/?left=pH-calculation&right=water-ion-product

 

[brake4country]

Thanks for the table but I still don't think I get it. Since this is for the mcat, how am I supposed to calculate the OH concentration at 10 C?

 

[Borek]

What is the definition of K_w?

 

[brake4country]

Kw is the equilibrium constant for [H+] and [OH-]. In aqueous solution, Kw remains at 10^-14.

 

[Borek]

In aqueous solution, Kw remains at 10^-14.

Have you really seen the table? What is the K_w value at 10°C?