What is the correct formula that would result from the combination of the two ionic species?
[tex]$NH _4^{+}$[/tex] and [tex]$SO _4{ }^{2-}$[/tex]
A. [tex]$NH _4(SO _4)_2$[/tex]
B. [tex]$(NH _4)_2 SO _4$[/tex]
C. [tex]$NH _4 SO _4$[/tex]
D. [tex]$SO _4(NH _4)_2$[/tex]
Answer (2)
Determine the charges of the ions: N H 4 + has a charge of +1, and S O 4 2 − has a charge of -2.
Balance the charges to form a neutral compound: x ( + 1 ) + y ( − 2 ) = 0 , where x is the number of N H 4 + ions and y is the number of S O 4 2 − ions.
Solve for the simplest whole number ratio: x = 2 and y = 1 .
The correct formula is ( N H 4 ) 2 S O 4 , representing two ammonium ions and one sulfate ion. ( N H 4 ) 2 S O 4
Explanation
Understanding the Problem We are given two ionic species: N H 4 + and S O 4 2 − . Our goal is to determine the correct chemical formula that results from the combination of these ions. The chemical formula must be neutral, meaning the total positive charge must equal the total negative charge.
Identifying Charges The ammonium ion, N H 4 + , has a charge of +1. The sulfate ion, S O 4 2 − , has a charge of -2. To form a neutral compound, we need to balance these charges.
Balancing Charges Let x be the number of N H 4 + ions and y be the number of S O 4 2 − ions. The total charge of the compound can be expressed as: x ( + 1 ) + y ( − 2 ) = 0 This simplifies to: x − 2 y = 0 x = 2 y
Determining Ion Ratio The simplest whole number solution for x and y is x = 2 and y = 1 . This means we need two ammonium ions ( N H 4 + ) for every one sulfate ion ( S O 4 2 − ) to achieve a neutral compound.
Final Formula Therefore, the correct chemical formula is ( N H 4 ) 2 S O 4 . This formula indicates that there are two ammonium ions and one sulfate ion in the compound, resulting in a net charge of zero: 2 ( + 1 ) + 1 ( − 2 ) = 0 .
Examples
Understanding ionic compounds is crucial in various fields, such as medicine and environmental science. For instance, in medicine, saline solutions used for intravenous drips are composed of sodium ( N a + ) and chloride ( C l − ) ions, forming sodium chloride (NaCl). The correct balance of these ions is essential for maintaining the body's electrolyte balance. Similarly, in agriculture, fertilizers often contain ammonium sulfate ( ( N H 4 ) 2 S O 4 ), which provides nitrogen to plants. Knowing the correct formula ensures that the right amount of nutrients is delivered, optimizing plant growth and preventing environmental pollution.
The correct formula formed by combining N H 4 + and S O 4 2 − is ( N H 4 ) 2 S O 4 , indicating two ammonium ions and one sulfate ion. This formula ensures that the compound is neutral, as the total charge balances to zero. Therefore, the chosen option is B.
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