Select the correct formula for the polyatomic ion. You can find a list of common polyatomic ions by clicking here.
The formula for ammonium carbonate:
A. $NH _4 \cdot HCO _3$
B. $NH _4 CO _3$
C. $\left( NH _4\right)_2 CO _3$
Answer (2)
Identify the ammonium ion as N H 4 + and the carbonate ion as C O 3 2 − .
Recognize that two ammonium ions are needed to balance the -2 charge of the carbonate ion.
Combine the ions in the correct ratio to form the neutral compound.
The correct formula for ammonium carbonate is ( N H 4 ) 2 C O 3 .
Explanation
Understanding the Problem We need to determine the correct chemical formula for ammonium carbonate. This involves understanding the formulas and charges of the ammonium and carbonate ions and combining them in the correct ratio to form a neutral compound.
Identifying the Ions The ammonium ion has the formula N H 4 + and a charge of +1. The carbonate ion has the formula C O 3 2 − and a charge of -2.
Balancing the Charges To form a neutral compound, the total positive charge must equal the total negative charge. Since ammonium has a +1 charge and carbonate has a -2 charge, we need two ammonium ions to balance one carbonate ion. This gives us the formula ( N H 4 ) 2 C O 3 .
Final Answer Therefore, the correct formula for ammonium carbonate is ( N H 4 ) 2 C O 3 .
Examples
Ammonium carbonate is used in smelling salts and as a leavening agent in baking. Understanding how to correctly write chemical formulas is crucial in chemistry for predicting reactions and understanding the properties of different compounds. For example, if you were synthesizing a fertilizer containing ammonium carbonate, you would need to know the correct formula to ensure you have the right proportions of nitrogen, carbon, hydrogen, and oxygen. This knowledge also helps in calculating the molar mass and determining the amount of each element present in a given mass of the compound.
The correct formula for ammonium carbonate is ( N H 4 ) 2 C O 3 , as it consists of two ammonium ions balancing one carbonate ion's charge. This ensures that the compound is neutral overall. Therefore, the answer is Option C: ( N H 4 ) 2 C O 3 .
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