Since you are asking this question, I assume that you are new to the game and so you don't strike the ball consistently all the time.  Hey, we all had to be beginners sometime.\nTherefore, for now, if you are more than 100 yards away from the pin use your 5-iron.  Inside 100 yards, use a more lofted club like your 9-iron or pitching wedge if you have one.\nAs you progress, spend some time at the range just learning to strike the ball solidly.  At the same time you will learn how far each club goes when you hit it right and then you can use that on the course later.  Also, if you think you like the game, why not sign up and take just three lessons from a pro.  He'll get you swinging correctly and you'll progress faster.