If you flip a coin 150 times about how many times would you expect to get heads?

You cannot have any expectations, statistics cannot apply here, you are as likely, in theory to get 150 heads as none at all as each coin toss is totally independent of the one before and after.
Chaos theory would probably show that you are unlikely to get more or less than a certain number of heads or tails but mathematically there is absolutely no way of predicting a percentage out of any number of tosses.