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Decomposition of Sodium Bicarbonate Stoichiometry Lab, Lab Reports of Chemistry

Stoichiometry Lab on baking soda. Complete worksheet for better preparation of exams

Typology: Lab Reports

2021/2022

Uploaded on 02/03/2022

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Decomposition of Sodium Bicarbonate Stoichiometry Lab
OBJECTIVES
The purpose of this lab is to:
-Perform a decomposition reaction and measure the mass of the product(s) formed
-Using stoichiometry to determine which thermal decomposition reaction occurred during
the experiment
-Calculate the percent yield and error for your experiment.
BACKGROUND
The word stoichiometry originates from the Greek words stoicheion; meaning element and
metron; meaning measure. We use stoichiometry to describe the relationship between the
relative quantities of substances taking part in a reaction or forming a compound, and are
typically a ratio of whole integers. In this lab, you will use stoichiometry to probe the
decomposition of sodium bicarbonate. Sodium bicarbonate may be more familiar to you as
baking soda. Baking soda is very commonly listed as an ingredient in recipes for baked goods,
pancakes and waffles. As the food item is being cooked or baked, the baking soda undergoes
decomposition, releasing gas and causing the food item to “rise” and have a “light” texture.
There are three theoretically possible chemical reactions that could occur during the thermal
decomposition of baking soda.
1) sodium bicarbonate (s) → sodium hydroxide (s) + carbon dioxide (g)
2) sodium bicarbonate (s) → sodium oxide (s) + carbon dioxide (g) + water (g)
3) sodium bicarbonate (s)→ sodium carbonate (s) + carbon dioxide (g) + water (g)
By comparing the theoretical yields of the possible solid products with the actual experimental
yield of the product, you will be able to determine which of the above decomposition reactions
occurred.
REQUIRED SUPPLIES
Sodium bicarbonate Bunsen Burner Crucible
Ceramic triangle Iron ring clamp Balance
Crucible tongs
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Decomposition of Sodium Bicarbonate Stoichiometry Lab

OBJECTIVES

The purpose of this lab is to: -Perform a decomposition reaction and measure the mass of the product(s) formed -Using stoichiometry to determine which thermal decomposition reaction occurred during the experiment -Calculate the percent yield and error for your experiment.

BACKGROUND The word stoichiometry originates from the Greek words stoicheion; meaning element and metron; meaning measure. We use stoichiometry to describe the relationship between the relative quantities of substances taking part in a reaction or forming a compound, and are typically a ratio of whole integers. In this lab, you will use stoichiometry to probe the decomposition of sodium bicarbonate. Sodium bicarbonate may be more familiar to you as baking soda. Baking soda is very commonly listed as an ingredient in recipes for baked goods, pancakes and waffles. As the food item is being cooked or baked, the baking soda undergoes decomposition, releasing gas and causing the food item to “rise” and have a “light” texture. There are three theoretically possible chemical reactions that could occur during the thermal decomposition of baking soda.

  1. sodium bicarbonate (s) → sodium hydroxide (s) + carbon dioxide (g)
  2. sodium bicarbonate (s) → sodium oxide (s) + carbon dioxide (g) + water (g)
  3. sodium bicarbonate (s)→ sodium carbonate (s) + carbon dioxide (g) + water (g) By comparing the theoretical yields of the possible solid products with the actual experimental yield of the product, you will be able to determine which of the above decomposition reactions occurred.

REQUIRED SUPPLIES Sodium bicarbonate Bunsen Burner Crucible Ceramic triangle Iron ring clamp Balance Crucible tongs

PROCEDURE

  1. Place a clean crucible on a ceramic triangle that is sitting on a iron ring clamp attached to a ring stand.

  2. Using a Bunsen burner heat the crucible for 5 minutes on a low temperature and then allow to cool for approximately 10 minutes.

  3. Bring your fingernail close to the crucible to determine if the crucible has cooled. Please note, that once the crucible has been heated, you cannot touch the crucible for the duration of the experiment with your fingers. The crucible is a porous material and will absorb the oils from your fingers skewing your experimental results.

  4. Using crucible tongs, carry the crucible to the balance to get the mass of the cool crucible.

  5. Add between 4-5g of sodium bicarbonate to the crucible and record the exact mass of the sodium bicarbonate being used.

  6. Heat the crucible and sodium bicarbonate on a low flame for 2 minutes and then on a medium-high flame for 8-10 minutes.

  7. After allowing the crucible to cool, take the mass of the crucible and product (s).

  8. Repeat the heating of the crucible on a low flame followed by the medium-high flame again.

  9. Once the crucible has again cooled take the mass of the crucible and product again. If the mass difference between the two heating cycles is greater than 0.1g, repeat the heating process again to ensure that the thermal decomposition has been completed and all of the gas products have been driven off.

  10. Once the mass of product and crucible remain constant, discard the solid product as directed by your instructor, wash and dry the crucible and return all equipment to their initial location.

C) Mass of sodium bicarbonate used in the experiment (B-A) ________________g

D) Moles of sodium bicarbonate used in the experiment ________________g

E) Mass of crucible and decomposition product after the first heating ________________g F) Mass of crucible and decomposition product after the second heating ________________g G) Mass of crucible and decomposition product after third heating (if required) ________________g H) Mass of decomposition product (E or F – A) ________________g

DATA ANALYSIS AND POSTLAB QUESTIONS

  1. Using the moles of sodium bicarbonate actually used in the experiment, calculate the theoretical yield of products from each of the possible decomposition reaction.

  2. Which theoretical yield agrees with the experimental yield?

  3. Which balanced chemical reaction actually occurred during this experiment?

  4. What is the percent yield?

  1. What is the percent error associated with the experiment?

REFERENCES

  1. Adapted from “AccelLab19--‐DecompBakingSodaStoich” from http://www.gobookee.org/get_book.php?u=aHR0cDovL3Bocy5wcnMuazEyLm5qLnVzL2pnaWFt bWFuY28vQWNjZWxDaGVtL0xhYnMvQTE5TGFiLURlY29tcEJha2VTb2RhLnBkZgpMYWIgIyAxOTog RGVjb21wb3NpdGlvbiBvZiBCYWtpbmcgU29kYSBTdG9pY2hpb21ldHJ5IC4uLg==
  2. Adapted from “Baking soda stoich lab,” Dr. Breinan