Just my $.02...
I have a page that - some time ago - had an url
and it was 197th in the google search for the 'something' KW.
I have changed it to
no other changes (apart from changes in internal links throughout
the site - but anchor texts remained unchanged,no new links were
added and so on).
First the page disappeared completely from the SERPS, after two
weeks from the change it was back - as 119th. Now it is 97th (still
no further changes on my side and no IBL changes that I know off).
http://www.chembuddy.com - chemical calculators for labs and education
BATE - program for pH calculations
CASC - Concentration and Solution Calculator
pH lectures - guide to hand pH calculation with examples