[easyorganic]

I'm sorry, you are correct going to less polar solvent will slow SN1, however you are changing concentration too.

Well what is the definition of molarity?  Its moles something per liter.  Figure out your total moles and then divide  it by the total volume.

This is one of the biggest problems in our ochem chem labs, students don't know gen chem, basic definitions and unit conversions.  It seems as soon as gen chem is over, they purge it from their brains.

[orgopete]

Just to keep this going in the correct direction, it doesn't matter what the product is, HCl is released. The NaOH/indicator simply times the reaction rate. What is varied is the amount of water or water/acetone. It’s the water that increases the reaction rate though. The t-butylchloride is the number of moles per total volume present. It should be the same for all the variations, if done as we had in our labs.