Purpose: To compare the effects of temperature, concentration, and surface area on the rate of a reaction. C 6 H 8 O 7(aq) + 3NaHCO 3(aq) → 3H 2 O (l) + 3CO 2(g) + Na 3 C 6 H 5 O 7(aq) citric acidcitric acid + baking soda → water + carbon dioxide + sodium citratebaking sodawatercarbon dioxidesodium citrate

Materials:2 250 mL beakers Hot plate Water Ice 2 Alka-Seltzer Tablets Pasco CO 2 Probe Mortar and Pestle

Procedure: 1. Break each of tablets into FOUR equal pieces for the 6 trials you will be conducting. 2. Add 50 mL of tap water into your reaction chamber. Drop one-fourth tablet into the canister and at the same time, start the Pasco Probe and place it in the mouth of the chamber. 3. Stop the probe when the CO2 concentration reaches 20,000 ppm and record the time in seconds.

Procedure (cont.): 3. Repeat this procedure for Trial 2 but now grind the quarter tablet into powder using the mortar and pestle. 4. After the 2 trials with tap water, repeat your experiments (trials 3 and 4) with ice water and then finally with warm, not boiling water (5 and 6). 5. Record the ambient CO2 concentration in the classroom to use as the initial concentration.

Tap WaterWarm WaterIce Water Time (s) Whole Powder

Data Analysis: 1. Calculate the reaction rate for each trail using the following equation: 4. Write a short paragraph with your conclusion about the effects of temperature and surface area on reaction rates. average rate =  [CO 2 ] tt = [CO 2 ] final – [CO 2 ] initial t final - t initial