Chemistry lab report

Alka-Seltzer Rocket Formal Lab Report

Abstract
In the Alka-Seltzer Rocket lab one was to experimentally determine how much (grams) Alka-Seltzer and water in mL, is needed to launch the rocket the highest/longest distance in cm. Also to experimentally determine the % NaHCO3 in the tablet using the information from the highest/longest distance. Calculate the error and % error of NaHCO3 in an Alka-Seltzer tablet and to determine the limiting reagent for the highest/longest distance traveled. Alka-Seltzer tablets were first obtained. Vinegar, a 250-mL beaker, and a 50-mL (or 10-mL) graduated cylinder was given from the instructor. After the experiment, a graph of percent by mass of the reacted NaHCO3 in a tablet versus the volume of vinegar used was constructed.
Methods/Experimental
chen,Yueh-huey, and Jing-Fun Young, Alka Seltzer fizzing-determination of percent by mass of NaHCO3 in alka seltzer tablets, J.Chem. Educ., 79, (July 2002), 848-850.
Results/Calculations
The limiting reagent is acetic acid from 0-20 Ml while baking soda is the excess. When the volume of vinegar was increase, more sodium bicarbonate reacted and more CO2 was produced. The percent by mass of the reached sodium bicarbonate rose with increasing amounts of vinegar. The limiting reagent is baking soda from 25-35 ml while acetic acid is the excess. The percent by mass reacted sodium bicarbonate in the tablet increased with the amount of vinegar used and then came to a steady value. The amount of CO2 produced was the same as the quantity of sodium bicarbonate in the tablet. When the volume of acetic acid was 0, the mass of CO2 (loss of mass) is 0.68g. This was found by subtracting the total mass of beaker and contents after reaction. The mass of NaHCO3 in tablet is 1.3g. This was found by multiplying the mass of CO2 produced and molar mass NaHCO3 and then dividing that by molar mass CO2. The percent of NaHCO3 in tablet when the volume of acetic acid was 0 was 415. This was found by dividing the mass of NaHCO3 in tablet by the mass of tablet and then multiplying that by 100. The average mass of NaHCO3 in this experiment is 1.5g. This was found by adding all of the masses of NaHCO3 and then dividing them by the trials (8). The error in the lab is .416 NaHCO3. This was found by subtracting the known mass of NaHCO3 by the average mass of NaHCO3.The percent error in this lab is 22.8%. This was found by dividing the error by the known mass of NaHCO3 and then multiplying by 100.
Mass of CO2(loss of mass):
44.12 - 43.44 = 0.68
Mass of NaHCO3 in tablet:
0.68g CO2 x 1 mol CO2 x 1 mol / 1 mol CO2 x 84.0g / 1mol NaHCO3 = 1.3g NaHCO3
% of NaHCO3 in tablet:
1.3g / 3.20g = 0.40625
0.40625 x 100 = 41%
Average mass of NaHCO3 in tablet:
1.3 + 1.2 + 1.4 + 1.5 + 1.6 + 1.6 + 1.6 + 1.6 = 11.8
11.8 / 8 = 1.5g of NaHCO3
Average % of NaHCO3 in tablet:
41 + 38 + 43 + 46 + 48 + 48 + 48 + 48 = 360
360 / 8 = 45% NaHCO3 in tablet.
Error:
1.916 – 1.5 = .416g NaHCO3
% error:
.436 / 1.916 = .227557411
.227557411 x 100 = 22.8%

Discussion
In the Alka-Seltzer Rocket lab one was to experimentally determine how much (grams) Alka-Seltzer and water in mL, is needed to launch the rocket the highest/longest distance in cm. Also to experimentally determine the % NaHCO3 in the tablet using the information from the highest/longest distance. Calculate the error and % error of NaHCO3 in an Alka-Seltzer tablet Alka-Seltzer Rocket Lab 5 and to determine the limiting reagent for the highest/longest distance traveled. Alka-Seltzer tablets were first obtained. Vinegar, a 250-mL beaker, and a 50-mL (or 10-mL) graduated cylinder was given from the instructor. An electronic balance (±0.01 g) was also given and used for all the weight measurements. One was to run a number of reactions with various ratios of vinegar/water. The total volume of vinegar–water solution for each run was 35 mL. The volume of vinegar in the solutions was varied from 0 to 35 mL in 5-mL increments. The experiment was started by measuring the mass of one tablet and the total mass of the 35-mL vinegar–water solution in the cup. The tablet was then dissolved in the vinegar–water solution. The cup containing the reaction mixture was carefully swirled to ensure complete dissolution of the tablet. The total mass of the reaction mixture in the cup was measured when the reaction (bubbling) stops. The procedure was repeated with all vinegar–water solutions, and the percent by mass of the reacted NaHCO3 in a tablet is calculated for each run of the reaction. After the experiment, a graph of percent by mass of the reacted NaHCO3 in a tablet versus the volume of vinegar used was constructed. The percent by mass of the reacted sodium bicarbonate in the tablet initially increased with the amount of vinegar used and then reached a steady value. As shown in the graph, when less than 20 mL of vinegar was used, the acid was the limiting reactant. When the volume of vinegar was increased, more sodium bicarbonate reacted and more CO2 was produced. The percent by mass of the reacted sodium bicarbonate increased with increasing amounts of vinegar. When the volume of vinegar exceeded 20 mL, Sodium
Bicarbonate became the limiting reactant. Since the content of sodium bicarbonate is fixed, the amount of the product (CO2 ) remained unchanged regardless of the volume of vinegar used and the percent by mass of the reacted NaHCO3 showed a constant value. Error in the lab could’ve occurred when using different beakers due to sizes or water could’ve possibly been left in the beaker before adding additional water for the next trial. An error could’ve occurred when moving the Alka-Seltzer tablets from inside the classroom to outside because the tablets were only placed on a towel. Parts of the tablet could’ve fallen off of the towel when moving. This means that the tablets wouldn’t have weighed as much as one thought they did. Improving this lab could include, using the same size beaker and same type of beaker so no beaker weighs more than the other. Also drying off each beaker before adding additional water could be done so additional weight is not added. An additional improvement could be made by using something to hold each weighed out tablet so no excess can fall off while moving them from the classroom to outside.
Conclusion
In the Alka-Seltzer Rocket lab the percent by mass of the reacted sodium bicarbonate in the tablet initially increased with the amount of vinegar used and then reached a steady value. As shown in the graph, when less than 20 mL of vinegar was used, the acid was the limiting reactant. When the volume of vinegar was increased, more sodium bicarbonate reacted and more CO2 was produced. The percent by mass of the reacted sodium bicarbonate increased with increasing amounts of vinegar. When the volume of vinegar exceeded 20 mL, Sodium Bicarbonate became the limiting reactant. Since the content of sodium bicarbonate is fixed, the amount of the product (CO2 ) remained unchanged regardless of the volume of vinegar used and the percent by mass of the reacted NaHCO3 showed a constant value. Error in the lab could’ve occurred when using different beakers due to sizes or water could’ve possibly been left in the beaker before adding additional water for the next trial. An error could’ve occurred when moving the Alka-Seltzer tablets from inside the classroom to outside because the tablets were only placed on a towel. Parts of the tablet could’ve fallen off of the towel when moving. This means that the tablets wouldn’t have weighed as much as one thought they did. Improving this lab could include, using the same size beaker and same type of beaker so no beaker weighs more than the other. Also drying off each beaker before adding additional water could be done so additional weight is not added. An additional improvement could be made by using something to hold each weighed out tablet so no excess can fall off while moving them from the classroom to outside.