Rates if Reaction GCSE Cousrework

Introduction
I am investigating what affects the rate at which to reactants react and make a product. The two reactants in particular are marble (CaCO3) and hydrochloric acid (2HCl); the products that they produce are carbon dioxide (CO2), water (H20) and a calcium chloride (CaCl2). The product that will be measured (to show that the reaction has taken place) will be carbon dioxide, as a gas it can easily be bubbled off and measured in burette. The test will be time related e.g. seeing how long the mixture took to fill a 50 ml burette with carbon dioxide.
Values and Variables
The definiti…