Rate of Dissolution Activity Lab

Popping Film Canisters and Rate of Dissolution/ Reaction-(Class Set) Wear Goggles! Purpose – Research which variable affects the rate that Alka Seltzer tablets dissolve in water. Introduction - Alka Seltzer is an over the counter indigestion medicine. A fun way to study dissolving rates is to place Alka Seltzer in water in a film canister and time how long it takes until the lid pops off. Each time you place the Alka Seltzer in the film canister, you will first change one variable to see how that affects the time until the top pops off. Background –The active ingredients of Alka Seltzer tablets are sodium bicarbonate (baking soda), citric acid from fruit juice and acetylsalicylic acid (aspirin). Bubbles of CO2 gas are produced whenever an acid is added to baking soda. In the present case, there are two acids – citric acid and aspirin. So there are two reactions producing carbon dioxide. The first reaction is between the baking soda and citric acid. The second reaction is between the baking soda and the aspirin. Alka Seltzer is an anti-acid because both the sodium citrate and the sodium acetylsalicylate neutralize the excess stomach acid. The carbonation produced by dissolving carbon dioxide gas in water also settles the stomach, as anyone knows who drinks a carbonated soft drink to treat a mild upset stomach. Procedure – Your group will rotate through 4 labs stations (about 5 mins/ station). At each lab station, you will test one variable to see how it affects the time it takes to pop the top of the film canister. At Each Lab Table, Read ALL directions before beginning. Be ready to complete steps quickly and to ACCURATELY record the time it takes the top to pop off. Safety – Point canister tops AWAY from all people. 1. Station 1- temperature a) Fill film canister ½ full with cold water. (ice water) b) Place ¼ tablet into film canister and cover with lid. c) How long in seconds does it take to pop off the top? Use a timer from time you insert Alka Seltzer until the top pops off. d) Record your results in the data table. e) Clean out film canister in sink, clean up any spills or splashes. f) Repeat Steps #1-4, except this time, use warm water. (tap water) g) Repeat Steps #1-4, except this time, use hot water. (on hot plate) 2. Station 2- Surface Area a) Fill film canister ¼ full with room temperature water. b) Place ¼ tablet into film canister and cover with lid. c) How long in seconds does it take to pop off the top? Use a timer from time you insert Alka Seltzer until the top pops off. Record your results in the data table. d) Clean out film canister in sink, clean up any spills or splashes e) Repeat steps # 1-4 except this time, break the ¼ piece tablet piece into 2 smaller pieces. (put both pieces in) f) Repeat steps #1-4 except this time, break the ¼ piece of tablet piece into 3-4 smaller pieces. (put all the pieces in) g) Repeat steps #1-4 except this time, crush the ¼ piece of tablet piece into a powder. (put powder on lid, flip & close) 3. Station 3- Amount of solvent a) Fill film canister ¼ full with room temperature water. b) Place ¼ tablet into film canister and cover with lid. c) How long in seconds does it take to pop off the top? Use a timer from time you insert Alka Seltzer until the top pops off. Record your results in the data table. d) Clean out film canister in sink, clean up any spills or splashes e) Repeat Steps #1-4, except this time, fill the canister to ½ full. f) Repeat steps # 1-4, except this time, fill the canister to ¾ full. 4. Station 4- Agitation a) Fill film canister ¼ full with room temperature water. b) Place ¼ tablet into film canister and cover with lid. c) How long in seconds does it take to pop off the top? Use a timer from time you insert Alka Seltzer until the top pops off. Record your results in the data table. d) Clean out film canister in sink, clean up any spills or splashes e) Repeat Steps #1-4, except this time, shake canister for 1 second after placing lid on canister. f) Repeat steps # 1-4, except this time, shake the canister for 2 seconds before placing lid on canister. Name: ______________________________ per:____ Rate of Dissolution/ Reaction Lab- Data Sheet Data/Observations: Temperature cold water warm water Hot water Time in seconds Surface Area 1 piece (1/4 tablet) 2 pieces (1/2 the ¼) 3 small pieces Crushed pieces ¼ full ½ full ¾ full No shake 1 sec shake 2 sec shake Time (sec.) Concentration Time in seconds Agitation Time in seconds Analysis Q’s 1. Describe what causes the lid to pop off the canister no matter what variable you are testing. 2. Identify the solute and the solvent used in this activity. 3. For EACH lab table/variable tested, state the variable you changed AND how it affected the variable you measured. (ex: For the Temperature station we changed _____ & it caused ______to happen). 4. Why would you expect a packet of sugar to dissolve faster in hot tea than in iced tea? (answer questions on back) Name: ______________________________ per:____ Rate of Dissolution/ Reaction Lab- Data Sheet Data/Observations: Temperature cold water warm water Hot water Time in seconds Surface Area 1 piece (1/4 tablet) 2 pieces (1/2 the ¼) 3 small pieces Crushed pieces Time (sec.) Amount of Solvent ¼ full ½ full ¾ full No shake 1 sec shake 2 sec shake Time in seconds Agitation Time in seconds Analysis Q’s 1. Describe what causes the lid to pop off the canister no matter what variable you are testing. 2. Identify the solute and the solvent used in this activity. 3. For EACH lab table/variable tested, state the variable you changed AND how it affected the variable you measured. (ex: For the Temperature station we changed _____ & it caused ______to happen). 4. Why would you expect a packet of sugar to dissolve faster in hot tea than in iced tea? (answer questions on back)