Lina has  some  white crystalline solid which she claims  to be a salt called ammonium carbonate.  How can you prove or disprove her claim?

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bandmanjoe's profile pic

bandmanjoe | Middle School Teacher | (Level 2) Senior Educator

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Ammonium carbonate is a crystalline, white powder, that is soluble in hot water.  When crushed into its powder form, it is used as smelling salts, which can bring an unconscious person back to consciousness due to its sharp, acrid smell produced by the ammonia part of the formula.  Ammonium carbonate (NH4)2CO3 is also known as "bakers ammonia", as it was used historically as a leavening agent in the production of breads and other baked goods before the use of baking soda.  The mixing of ammonium carbonate with a base would release the ammonia part of the equation, which would be an indication of the accuracy of naming the compound.  The application of an acid, such as vinegar, would produce bubbles from the release of the carbonation, which would come off in the form of carbon dioxide, which would indicate an accurate chemical identification.

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najm1947's profile pic

najm1947 | Elementary School Teacher | (Level 1) Valedictorian

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Lena claims it to be ammonium carbonate. The substance must yield the ammonia gas and carbon dioxide gas when treated with caustic soda solution and dilute hydrochloric acid respectively as given by the following chemical equations:

(NH4)2.CO3 + 2NaOH = Na2CO3 + 2H2O +2NH3 (gas)

Ammonia gas NH3 can be recognised by its peculiar pungent smell

and

for the other part take a beaker, add some of the Lena's substance into it and pour some dilute hydrochloric acid on it and cover the beaker. There will be bubbling and carbon dioxide will be collected in the beaker.

(NH4)2.CO3 +2HCl = 2NH3Cl + 2H2O +CO2 (gas)

Carbon dioxide gas can be identified by entering a burning match stick in the beaker which will get extinguished if it was carbon dioxide gas. Other tests for it can also be done for identification of gas if it is collected by in a separate container by upward replacement of air.

If the two conditions are fulfilled, Lena's claim is proved otherwise if any of the conditions is not fulfilled, her claim is disapproved and is false.

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