- #1

- 3

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Three Alka-Seltzer tablets

Water

Three coffee cups

Ice

Thermometer

Watch with seconds

Procedure:

Chill some water with the ice.

Pour just the water into one coffee cup.

Heat some water and place it in a second coffee cup.

Put room temperature water into the third cup.

Use the thermometer to record, in a data table, the temperature of the water in each cup.

Simultaneously (get help from another person), add one full Alka-Seltzer tablet to each cup and begin timing with your watch.

Record the amount of time needed for each reaction to reach conclusion (stops fizzing).

Graph your results.

Part 2:

Materials

Three Alka-Seltzer tablets

Water

Spoon

Three coffee cups

Watch with seconds

Procedure

On a piece of paper, grind up one tablet with the back of the spoon until it is a fine powder.

On a second piece of paper, chop one tablet into several small pieces but do not grind it.

Fill the three cups with the same amount of water

Note: the water should be approximately the same temperature at the start.

Simultaneously (again, get help), add the ground tablet to one cup, the chopped tablet to a second cup, and the whole tablet to the third cup. Begin timing with your watch.

Record the amount of time needed for each reaction to reach conclusion (to stop fizzing).

Graph your results.

Note: On the Y axis = time of reaction; on X axis where you are putting "surface area exposed" use 1 = for whole tablets; 5 for small pieces; 10 for crushed.

Analysis:

What differences did you observe in the reactions in the three cups in Part I?

Look at your graph of temperature vs. reaction time. Describe this graph in mathematical terms—e.g., linear, parabolic (curved up).

As temperature increases, what happens to reaction time?

What differences did you observe in the reactions in the three cups in Part II?

Look at your graph of surface area vs. reaction time. Describe this graph in mathematical terms.

As surface area increases (smaller particles), what happens to reaction time?

Based on your data, under what conditions would you expect the reaction between baking soda and vinegar to occur most quickly?