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Air Bag Experiment

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We did an experiment to determine how many grams of NaHCO3 and 0.8 M H2SO4 were required to inflate a quart-sized Ziploc bag. We determined the volume of the Ziploc bag to be 1.350 L. Using the ideal gas law, the molar calculation was 0.547 mols. We did 2 different scenarios. One was with the NaHCO3 as the limiting reagent, the other was with the H2SO4 as the limiting reagent.

For initial limiting reagent calculations, we came up with 4.60 g NaHCO3 and 34.2 mL H2SO4. The post-lab question that's confusing us is: Assume your 1st trial (using "A" grams of solid and "B" mL of acid solution) results in the bag not inflating completely. Assuming ONE of the two reactants is in excess and one is limiting. How could you figure out which one is in excess and which one is limiting by doing exactly one more trial?

Additionally, we have to "explain in detail what changes we would make and how we would interpret the possible outcomes of the trial?" It's been a while since we dealt with limiting reagents, and my lab partner and I are confused on how to answer these post-lab questions. Thanks in advance for your help!

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Solution Preview

One way to find out the limiting reagent would be to take the starting material, A grams and B mL, and add twice as much "A." If the A was originally the reagent in excess, then you should get no ...

Solution Summary

In this solution, the student originally asked for some clarification and explanation on how to determine the limiting reagent of a reaction in a real experiment.

The solution provides a suggested course of action and an explanation behind it.

See Also This Related BrainMass Solution

Ice Cream Experiment

This experiment will introduce the concept of homogeneous, heterogeneous, mixtures, solutions, and the colligative property of freezing point.

2 sandwich zip lock bags
2 one-gallon zip lock bags
1 cup half-half or 2% milk
2 Tbs. (tablespoons) sugar
1/8 tsp. (teaspoon) flavoring {Choose from: vanilla, banana, strawberry, peach, butter pecan, mint; or try chocolate powder}
(Optional) Food coloring to give your ice cream that special look
1-gallon of ice cubes
1 cup of salt
Paper towels to act as "pot holders"

1. The first step for making the ice cream is to wash your hands!
2. The next thing is to measure 1 cup of milk or half-half that you're going to use.
3. Take that milk or half-half and pour it into one of the sandwich size zip lock bags.
4. Next pour 2 Tbs. of sugar into the milk or half-half (If it all sinks to the bottom, you can shake it up to help dissolve it quicker).
5. Then add your choice of flavoring to mixture in the amount of 1/8 tsp. Add one or two drops of food coloring, if you so choose.
6. Squeeze out as much air as possible and zip the bag closed.
7. Put the milk mixture into another sandwich size bag, squeeze out as much air as possible and zip the milk mixture inside the second sandwich bag.
8. Shake the milk mixture until it turns into a homogeneous solution.
9. After all that you still have the two one-gallon bags. Fill one of the gallon size bags about ½ full of ice (It does not need to be perfect, you can eye it.), then add 1 cup of salt to the ice.
10. Put the double-bagged milk solution into the bag containing ice and salt. Add a few more pieces of ice. Squeeze out as much air as possible and zip the gallon bag closed. Place this bag inside another gallon bag and zip it closed.
11. Use paper towels like pot holders and shake the bag for ten minutes.
12. Carefully remove the double-bagged ice cream from the ice salt mixture. Rinse the salt off the ice cream bag.
13. {Optional} Open the ice cream bag and sample your chemical reaction.
14. With a thermometer measure the temperature of the ice salt mixture.

Questions (Use the words homogeneous and heterogeneous where appropriate.)
I. Describe all the times in this experiment where you were working with mixtures.
II. Describe all the times in this experiment where you were working with solutions.
III. What was the temperature of the ice-salt mixture. Challenge Question: Was it the same or was it higher or lower than you expected? Explain

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