Thursday, March 3, 2011

Thu, 3/3, Tucker

Today each lab group performed a short lab involving a reaction with alka-seltzer and water.  The reaction produced a gas and when this reaction occured in a flask with a balloon placed over the top of the flask, we were able to time the reaction...how long did it take for the balloon to inflate?  Since different groups investigated different independent variables, we then shared data/conclusions with the class.  The three labs are outlined below:

WE JUST WROTE THIS LAB IN OUR JOURNALS!!

Lab 1:
Procedure:  Place 1/4 alka seltzer tablets in 25ml of water in a 50ml flask and place a balloon over the top of the flask.  Time how long it takes for the balloon to inflate.  Repeat with 1/2 and full tablets.
Data:
1/4tablet-  45sec
1/2 tablet-  14sec
1 tablet-  6sec
Conclusion:  As concentration increases, so does the speed of the reaction

Lab 2:
Preocedure:  Place 1/2 alka seltzer in in 25ml of water in a 50ml flask and place a balloon over the top of the flask.  Time how long it takes for the balloon to inflate.  Repeat with a crushed alka-seltzer (which has more surface area!)
Data:
1/2 tablet -  16sec
1/2 tablet crushed- 5sec
Conclusion:  As surface area increases, so does the speed of the reaction

Lab 3:
Procedure:  Place 1/2 tablet of alka-seltzer in 25ml of room temperature water (22 degreesC) in a 50ml flask and place a balloon over the top of the flask.  Time how long it takes for the balloon to inflate.  Repeat this with 5degreesC water and 50 degreesC water.
Data:
5C- 2min, 20sec
22C-  20sec
50C-  4sec
Conclusion:  As temperature increases, so does the speed of the reaction

The independent variables for the lab were concentration, surface area, and temperature
The dependent varibale for the lab was time / speed of the reaction
The controlled varibales for the lab were the size of flask, type of tablets, and amount of water.

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