Introduction: This experiment will demonstrate how to produce and measure a gas



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Balloon Lab

Introduction: This experiment will demonstrate how to produce and measure a gas.

Purpose: To determine the amount of carbon dioxide gas produced from the reaction of sodium bicarbonate (NaHCO3) and acetic acid (HC2H3O2). The objectives for this lab are students will:

  1. Determine the amount of product that should be formed in a given reaction

  2. Perform a reaction mixing solutions together

  3. Observe and record data

  4. Use a percent error calculation to determine accuracy of calculations

  5. Present the material in a lab report


Hypothesis: After reading the entire lab, construct a hypothesis that answers the following questions with your OWN predictions.

  1. How will you tell the compounds have reacted?

  2. What amount of CO2 gas should you hope to find?

  3. How far off the predicted value will you be? (0.5%, 5%, 50%)

  4. Will filling the remainder of the bottle with water affect the results? If so, how?


Suggested Materials:

Lab goggles Meter stick string

Scale (with weigh paper) balloon empty cider bottle

2 250mL Beakers thermometer others???????


Reactants/Reagents:

NaHCO3 (sodium bicarbonate) HC2H3O2 (acetic acid)



Procedure:

  1. Measure 400 mL of HC2H3O2 (acetic acid) and pour it into the glass bottle.

  2. Stretch out the balloon and prepare to place it over the tip of the bottle neck.

  3. Mass out 30.0 g of NaHCO3 (baking soda).

  4. Put the NaHCO3 onto the balloon without spilling any. (This is where creativity comes in).

  5. Secure the balloon over the top of the bottle neck.

  6. Hold the balloon in place and empty the contents of the balloon into the bottle.

  7. Hold the balloon securely until it has stopped expanding.

  8. Use the string to measure the circumference of the balloon.

  9. Using a meter stick, measure the actual circumference of the balloon in centimeters.

  10. Clean up by disposing of solids in trash can and liquids down drain. Make sure lab station is clean and dry.


Additional Procedure:

  1. Follow procedures above but this time fill the bottle up with water after pouring in the acetic acid and see if there is a difference in the volume produced.


Pre-Lab Questions:

  1. Balance the equation for the reaction we will be preforming between sodium bicarbonate and acetic acid

__NaHCO3 + __HC2H3O2__H2O +__CO2 +__NaC2H3O2

  1. Identify the gas that should be filling up the balloon during the reaction.

  2. Use your understanding of the gas laws to explain why the balloon should be expanding.

  3. Calculate the theoretical volume of carbon dioxide produced if we start with 30.0 g NaHCO3 if today’s temperature is _________ and today’s pressure is _________.

Data Tables:



Observations during lab





Circumference of balloon

cm

Radius of the balloon

r = C/(2π)


cm


Volume of gas (observed yield)

V = 4/3 π r3


cm3



Convert your volume of gas from cm3 to L (1cm3 =1mL) (1000mL = 1L)

L

Percent Error

% error = actual yield – observed yield x 100

actual yield

%



Your pre lab should have these parts to it on a new sheet of paper:

Purpose: In your own words, write a 2-3-sentence overview on the purpose and objectives in this lab.

Hypothesis: State the hypothesis in clear language

Materials: Make a space to record what supplies you use during the lab.

Procedure: Make data table(s) to fill in information when you need to record. (See option above).

Practice Problems: Answer the above practice problems.
Your FINAL LAB should have these parts to it TYPED.

Purpose: In your OWN words, write 2-3-sentences on the purpose and objectives in this lab.

Hypothesis: State the hypothesis in clear language.

Materials: Write out in paragraph form all the materials used in the lab. (Include safety materials.)

Procedure: In paragraph form, tell the reader, like story, what steps were taken in your lab. ****Include figure 1 (a picture illustrating one of your procedure steps)

Theory of Relevant Principles: The essay of relevant principles should give background information (historical and/or theoretical) about the problem and how it relates to the lab. (Tips: Important facts about gases. Explain how a gas law relates to what occurred in the lab. How are gases used in society? Find information about CO2? Why is it important to be accurate and/or precise in a lab?)

Analysis: Begin the discussion by explaining and interpreting what you found and end it more broadly by placing your results in context. **** Include data tables and all your calculations (stoic, radius, volume, and %error).

Conclusion: Don't declare the experiment a success or failure. If poor results were obtained, discuss the results you expected as well as those you received. Do the results confirm your hypothesis? What are any areas for further study? How can the experiment be improved in light of possible errors? What did you learn from this experiment?

Works Cited: State if any sources were used (ie. The book, notes, lecture, internet, books).


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