can i calculate equilibrium constant of this reaction? Good day,
i had organic chemistry labs. And we had this reaction:
$$\ce{(CH3)3COH + HCl -&gt; (CH3)3CCl + H2O}$$

My question is:
how do i explain my yield of reaction is only 40%? 

My theory is:
reaction is reversible so the K isn't so high and that lead to yield 40%. 
If my theory is right please explain me how to calculate K?

I had these informations:

V$\ce{((CH3)3COH)}$ = 10 ml

V$\ce{(HCl)}$ = 20 ml
HCl was concentrated.

Thank for answers.
$\ce{H2O}$ is a very poor nucleophile and we are dealing with a tertiary substituted carbon, so we can minimize the scope of possible reaction mechanisms to the $\ce{E 1}$ and $\ce{S_{n}1}$ type mechanisms. $\ce{E 1}$ will compete here with $\ce{S_{n}1}$, forming tert-Butyl chloride and isobutylene respectively. That is probably where most of your loss is coming from. Other reasons can be indeed that a bit is left in the equilibrium, but I don't think that would be much since $\ce{H3O+}$ is a much better leaving group than $\ce{Cl-}$. Note that is chemistry papers the yield obtained is almost never a 100% of theory.