Fill in the name and empirical formula of each ionic compound that could be formed from the ions in this table:
| cation | anion | empirical formula | name of compound |
|---|---|---|---|
| [tex]Mg^{2+}[/tex] | [tex]MnO_4^-[/tex] | |
| [tex]Cr^{3+}[/tex] | [tex]OH^-[/tex] | |
| [tex]Ca^{2+}[/tex] | [tex]NO_3^-[/tex] | |
Answer (1)
Balance the charges of the cation and anion to determine the empirical formula.
Name the compound by stating the name of the cation followed by the name of the anion.
If the cation is a transition metal, indicate the charge with roman numerals in parentheses.
The empirical formulas and names are: M g ( M n O 4 ) 2 (Magnesium Permanganate), C r ( O H ) 3 (Chromium(III) Hydroxide), and C a ( N O 3 ) 2 (Calcium Nitrate).
Explanation
Problem Analysis We are given a table with cations and anions and asked to determine the empirical formula and name of the ionic compound formed by each cation-anion pair. The key is to balance the charges of the ions to create a neutral compound.
Magnesium Permanganate For M g 2 + and M n O 4 − , we need two M n O 4 − ions to balance the M g 2 + charge. Thus, the empirical formula is M g ( M n O 4 ) 2 . The name of the compound is Magnesium Permanganate.
Chromium(III) Hydroxide For C r 3 + and O H − , we need three O H − ions to balance the C r 3 + charge. Thus, the empirical formula is C r ( O H ) 3 . Since Chromium is a transition metal, we need to specify its charge. The name of the compound is Chromium(III) Hydroxide.
Calcium Nitrate For C a 2 + and N O 3 − , we need two N O 3 − ions to balance the C a 2 + charge. Thus, the empirical formula is C a ( N O 3 ) 2 . The name of the compound is Calcium Nitrate.
Final Answer Therefore, the completed table is:
cation
anion
empirical formula
name of compound
M g 2 +
M n O 4 −
M g ( M n O 4 ) 2
Magnesium Permanganate
C r 3 +
O H −
C r ( O H ) 3
Chromium(III) Hydroxide
C a 2 +
N O 3 −
C a ( N O 3 ) 2
Calcium Nitrate
Examples
Ionic compounds are used in various applications in everyday life. For example, sodium chloride (NaCl), or table salt, is used to season food. Calcium carbonate (CaCO3) is a common ingredient in antacids. Potassium iodide (KI) is added to table salt to prevent iodine deficiency. Understanding how these compounds are formed helps us understand their properties and uses.
