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Particle Size vs Rate of a Chemical Reaction | Alka-Seltzer

Effect of Particle Size on
Rate of Reaction

01Introduction

Big thoughts coming at you: The rate of a chemical reaction is affected by the physical size of the reactants. If this makes any sense to you then you are clearly a genius.

02Materials

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    3 Clear glasses

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    3 original formula effervescent
    Alka-Seltzer tablets

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    Mortar and pestle

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    Stopwatch

Particle size versus rate of reaction experiments materials

03Procedure

Part A. Whole Tablet

1.

Fill a clear glass with exactly 8 oz./240 mL of room temperature or lukewarm water.

2.

Drop 1 whole Alka-Seltzer tablet into the water. Measure and record the time to dissolve.

Alka-Seltzer tablet, broken, crushed

Part B. Tablet Broken into ~8 Pieces

1.

Place 1 Alka-Seltzer tablet onto a sheet of paper and break into approximately 8 pieces of about equal size.

2.

Fill a clear glass with exactly 8 oz./240 mL of room temperature or lukewarm water.

3.

Slide broken tablet into the water from the sheet. Measure and record the time to dissolve.

Part C. Powdered Tablet

1.

Place 1 Alka-Seltzer tablet into mortar and grind to a fine powder.

2.

Transfer powder into a clear cup. (Note: It's important to have the powder in the cup before adding water.)

3.

Add 8 oz./240 mL of water to the glass. Measure and record the time to dissolve.

04 CONCLUSION

Decreasing the size of the particles, which make up a given weight, will increase the number of particles represented by the same weight. Smaller particle size results in an increase in the rate of reaction because the surface area of the reactant has been increased.