Question

The ferricyanide ion has the formula \(\mathrm{Fe}(\mathrm{CN})_{6}^{3-}\). Write the formula for the compounds that ferricyanide would form with the cations of elements 3,13 , and 30 .

Short answer

Li3Fe(CN)6, AlFe(CN)6, Zn3[Fe(CN)6]2.

Step-by-step solution

Identify the cations of elements 3, 13, and 30

First, determine what the symbols and charges are for the cations of elements 3, 13, and 30. Element 3 is Lithium (Li) with a charge of +1, element 13 is Aluminum (Al) with a charge of +3, and element 30 is Zinc (Zn) with a charge of +2.

Write the formula for Lithium Ferricyanide

Next, combine the ferricyanide ion \(\text{Fe}(\text{CN})_6^{3-}\) with Lithium (Li\textsuperscript{+1}). Since ferricyanide has a charge of 3-, it will require 3 Lithium ions to balance the charge: \(\text{Li}_3\text{Fe}(\text{CN})_6\).

Write the formula for Aluminum Ferricyanide

Aluminum (Al\textsuperscript{+3}) has a charge of +3, which matches the -3 charge of a single ferricyanide ion. Therefore, the formula will be \(\text{AlFe}(\text{CN})_6\).

Write the formula for Zinc Ferricyanide

Zinc (Zn\textsuperscript{+2}) has a charge of +2. To balance the 3- charge of the ferricyanide ion, we need 3 ferricyanide ions and 2 Zinc ions to balance the charges: \(\text{Zn}_3(\text{Fe}(\text{CN})_6)_2\).

Key concepts

Ferricyanide Ion

The ferricyanide ion has the chemical formula \(\text{Fe}(\text{CN})_6^{3-}\). It is a complex ion where an iron (III) ion is surrounded by six cyanide ligands. The cyanide ions (CN-) are negatively charged, and they coordinate to the iron ion in a way that results in an overall charge of -3 for the entire complex. Understanding the structure and charge of this ion is essential for creating chemical formulas when it forms compounds with various cations.

Cation Charges

Cations are positively charged ions formed when an atom loses one or more electrons. Knowing the charges of cations is key to writing correct chemical formulas. Let's review the cations from elements 3, 13, and 30:

• Element 3: Lithium (Li) with a charge of +1.
• Element 13: Aluminum (Al) with a charge of +3.
• Element 30: Zinc (Zn) with a charge of +2.

With cation charges, we can balance them with the ferricyanide's 3- charge. The goal is to make the total charge of the compound equal zero.

Balancing Chemical Equations

When combining ions to form a compound, it's crucial that the total positive and negative charges balance to form a neutral compound. Here are the formulas for compounds formed by ferricyanide ion and the cations from elements 3, 13, and 30:

• Lithium Ferricyanide: Lithium (Li\(^+\)) has a charge of +1. To balance the -3 charge of the ferricyanide ion, you need three lithium ions: \(\text{Li}_3\text{Fe}(\text{CN})_6\).
• Aluminum Ferricyanide: Aluminum (Al\(^{3+}\)) has a charge of +3, which perfectly balances the -3 charge of one ferricyanide ion. The formula is simply: \(\text{AlFe}(\text{CN})_6\).
• Zinc Ferricyanide: Zinc (Zn\(^{2+}\)) has a charge of +2. To balance the -3 charge of the ferricyanide ion, you combine three ferricyanide ions with two zinc ions to achieve overall neutrality: \(\text{Zn}_3(\text{Fe}(\text{CN})_6)_2\).

By balancing the charges correctly, you ensure that the resulting compound is stable and neutral.