# Le Chatelier’s Principle: Concentration and Rxn Rate

You will examine the reaction of baking soda and vinegar (surprise! surprise!).  The reaction again is:

NaHCO3(s) + HC2H3O2(aq) ---> NaC2H3O2(aq) + CO2(g) + H2O(l)  Your question is: How does concentration affect reaction rate?

Procedures:

1. Obtain the following materials: 1 gas collecting flask, 1 large beaker, 1 small or medium beaker, 1 100mL graduated cylinder, 1 small piece of cardboard, and 1 stopwatch.
2. In the small beaker place 20g of NaHCO3 (baking soda); in the medium beaker place 100mL of vinegar.
3. Fill the graduated cylinder up to the brim with water and fill the large beaker ¾ full of water.  Place the cardboard on top of the graduated cylinder and quickly invert it and place in the large beaker of water.  (The goal here to not let any air in.)
4. Connect the rubber tubing as shown in the diagram below.
5. Place the 20g of baking soda into to square flask and put the top on.
6. When ready, add the 100mL of vinegar to the flask and start the stopwatch immediately.  BE CAREFUL NOT TO SPILL.  POUR SLOWLY BUT CONSISTENTLY.
7. After 50mL of gas have been formed, stop the stop watch and record the time.
8. Repeat three more times for diluted vinegar (as shown in data chart), using 20g baking soda each time.
 Vinegar Water % Vinegar Time (s) Rate (mL CO2/s) 100mL 0 mL 100% 50mL 50mL 50% 25mL 75mL 25% 12.5mL 87.5mL 12.5%

Graph the data carefully on a separate piece of paper.  Your dependent variable (on Y-axis) should be reaction rate and your independent (on X-axis) is % vinegar.

Question:  Describe the relationship between the concentration of vinegar and the rate of carbon dioxide production. (use back of page)

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