Explain why Montag hides books in the Blacks’ kitchen.

Once Montag decides that something must be done about the
burning of the books and the muder of some of the people that has come about because of the
necessity of burning the books, his original plan is to hide books in the homes of the
firefighters in order to turn the society against the firefighters in general  and hopefully
undermine their authority.

At the time, he is fleeing the
authorities and is partially sedated after his encounter with the hound, but he still sticks to
his original plan in the hopes that it might deflect some of fury of the manhunt, etc. by again
casting some of the light on someone else, in this case Black.