Which of the following correctly shows an ion pair and the ionic compound the two ions form?
A. [tex]$Sn ^4, N^3: Sn _4 N_3$[/tex]
B. [tex]$Cr ^{3+}, 1$ : Cr1[/tex]
C. [tex]$Cu ^{2+}, O ^{2-} ; Cu _2 O _2$[/tex]
D. [tex]$Fe ^{3+} \cdot O ^{2-}: Fe _2 O _3$[/tex]
Answer (2)
Check if the total positive charge equals the total negative charge for each option.
Option 1 ( S n 4 N 3 ): + 16 e q − 9 , not neutral.
Option 2 ( C r I ): + 3 e q − 1 , not neutral.
Option 3 ( C u 2 O 2 ): + 4 = − 4 , neutral, but not simplest form.
Option 4 ( F e 2 O 3 ): + 6 = − 6 , neutral and correct formula. The final answer is F e 2 O 3 .
Explanation
Understanding the Problem We are given four options, each consisting of an ion pair and the chemical formula of the ionic compound they form. We need to determine which option correctly represents the ion pair and the corresponding ionic compound. The correct ionic compound must be neutral, meaning the total positive charge must equal the total negative charge. The subscripts in the chemical formula represent the number of each ion needed to achieve neutrality.
Solution Plan For each option, we will calculate the total positive and negative charges based on the given ions and their charges. Then, we will check if the chemical formula is consistent with the charges of the ions and determine if the compound is neutral (total positive charge equals total negative charge). Finally, we will select the option where the ion pair and chemical formula are both correct and the compound is neutral.
Analyzing Option 1 Option 1: S n 4 + , N 3 − : S n 4 N 3 . The total positive charge is 4 × ( + 4 ) = + 16 . The total negative charge is 3 × ( − 3 ) = − 9 . Since + 16 e q − 9 , this compound is not neutral.
Analyzing Option 2 Option 2: C r 3 + , I − : C r I . The total positive charge is + 3 . The total negative charge is − 1 . Since + 3 e q − 1 , this compound is not neutral. The correct formula should be C r I 3 .
Analyzing Option 3 Option 3: C u 2 + , O 2 − : C u 2 O 2 . The total positive charge is 2 × ( + 2 ) = + 4 . The total negative charge is 2 × ( − 2 ) = − 4 . Since + 4 = − 4 (in magnitude), this compound is neutral. However, the formula can be simplified to C u O . While the charges balance, the given formula is not the simplest form.
Analyzing Option 4 Option 4: F e 3 + , O 2 − : F e 2 O 3 . The total positive charge is 2 × ( + 3 ) = + 6 . The total negative charge is 3 × ( − 2 ) = − 6 . Since + 6 = − 6 (in magnitude), this compound is neutral. The formula is correct and in its simplest form.
Conclusion Therefore, the correct option is F e 3 + × O 2 − : F e 2 O 3 because it correctly represents the ion pair and the neutral ionic compound they form.
Examples
Understanding how ions combine to form neutral compounds is crucial in various fields. For instance, in environmental science, predicting the formation of insoluble compounds helps in water treatment to remove toxic ions. In materials science, the properties of ionic compounds, such as their high melting points and electrical conductivity when dissolved, are utilized in designing new materials for batteries and sensors. Moreover, in medicine, understanding ionic interactions is essential for drug delivery and designing contrast agents for medical imaging. The ability to predict and control the formation of ionic compounds allows scientists and engineers to develop innovative solutions for a wide range of challenges.
The correct option is D: F e 3 + × O 2 − : F e 2 O 3 , as it accurately represents a neutral compound formed by the respective ions. Options A, B, and C do not produce neutral compounds or are not in their simplest forms. Checking the charge balance for ionic compounds confirms the accuracy of these formulas.
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