Pre-Lab Information Purpose Explore the rate of a chemical reaction at different temperatures and with different reactant particle sizes. Time Approximately 45 minutes Question What are the effects of temperature and a reactant’s particle size on reaction rate? Hypothesis 1 If you increase the temperature of a reaction, then the reaction rate will increase because particles experience more collisions at higher temperatures. Hypothesis 2 If you decrease the particle size of a reactant, then the reaction rate will increase because more of the reactants’ surface area is exposed allowing more particles to make contact with each other. Variables Independent variables: particle size, temperature Dependent variable: reaction rate Summary The reaction between effervescent tablets and water will produces CO2 gas, which you can observe in the form of bubbles; when the bubbling stops, the reaction is complete. You will measure the reaction times and rates for tablets dissolved at four temperatures and broken into three different particle sizes