Answer to Question #144044 in General Chemistry for Jake

Question

Some ball point pens have a small hole in the main body of the pen. What is the purpose of this hole?

Answer 1

While writing with the ball Pen the ink level in the capillary tube gradually decreases creating a vaccum inside the capillary tube of ink.

The small hole in the main body of the pen allow the air to pass through and fill the vaccum and push the ink from above.

If no such hole is present in the body of the ball pen there is no chance to fill that vaccum and air pressure out side the capillary do not let the ink to pass through the tip of the pen.

That's why some ball point pens have a small hole in the main body of the pen.