Alka-Seltzer Experiment

Introduction
Alka-Seltzer has been on the market since 1931 and has helped to relieve indigestion and upset stomach. The tablets began to fizz and bubble when dropped into water. “The fizziness happens when baking soda (sodium bicarbonate) and citric acid react chemically in water. They yield sodium citrate, water and carbon dioxide gas, which causes bubbles.” Based on this information, we will measure the reaction time of AlKa- Seltzer dissolved in 200 ml of water at 3 different tempertures in the first portion of this experiment. In the second portion of this experiment we will keep the temperature constant and divide the ½ tablet of Alka- Seltzer into 2 pieces ,3 pieces and an unbroken ½ tablet. It is my belief that Alka-Seltzer

Identify the independent
Variable

Size of the tablet
Identify the dependent
Variable

Reaction time
List the controlled variables The solution (water), temperature, volume of water (200 mls)
The amount of Alka- Seltzer
How will the dependent variables be measured A stop watch will be started as the pieces of
Alka-Seltzer are dropped into 200ml of room temperture water
Describe the expected results if the hypothesis is true The 3 smaller pieces of Alka Seltzer will dissolve quicker than the ½ tablet .

Data Table 2 dRun No. Cup Temp (*C) Time (sec.) observations ½ tab 17.9 55.30
1 ½ tab divided in 2 pc. 19.5 49.37 The pieces of alka-seltzer were drawn to each other in the cup ½ tab divided n 3 pc. 20.8 37.24 The pieces of alka-seltzer were drawn to each other in the cup ½ tab 19.4 52.01
2 ½ tab divided in 2 pc 19.5 49.5 ½ tab divided in3 pc 21.4 37.11 ½ tab 19.5 53.22
3 ½ tab divided in 2 pc 19.6 48.41 ½ tab divided in 3 pc 20.6 37.30
AVG ½ tab 18.9 53.51 ½ tab divided in 2pc 19.5 49.09 ½ tab divided in 3pc 20.9

Kinetic theory states that molecules are always in constant motion. Kinetic energy and molecule velocity increases as temperature increases. Reactions require collisions between reactant molecules or atoms. In chemical reactions, the reactants change into products when molecule collide with enough energy to break old bonds to make new ones. Collisions increase or become more violent between molecules at higher temperatures or decrease as the temperature is lowered. Some factors that influence the speed of a chemical reaction are: (1) surface area of starting reactants; (2) concentration of reactants; (3) temperatures. The particle theory states that a solute dissolved takes place at the surface of the solvent and the larger the surface area of the particle the longer it will take to dissolve. The smaller the area the faster it will