I'm just wondering, if you are diagnosed with a form of chronic leukemia can it change to an acute leukemia?

Yes, sometimes: There are two separate types of chronic leukemia;these go by the names CML and cll. They follow a separate course and can have a long course of disease. CML often ends up as acute leukemia(called blastic change which is a type of acute leukemia bearing poor survival once this transformation has taken place. Fortunately the risk of this happening is much reduced with the modern treatments for cml.