Problem 111 - Chemistry and Chemical Reactivity

Question

Write formulas for all of the compounds that can be made by combining the cations \(\mathrm{NH}_{4}^{+}\) and \(\mathrm{Ni}^{2+}\) with the anions \(\mathrm{CO}_{3}^{2-}\) and \(\mathrm{SO}_{4}^{2-}\)

Step-by-Step Solution

Answer

(NH4)2CO3, (NH4)2SO4, NiCO3, NiSO4

Step 1: Combining Ammonium Cation with Anions

First, we combine the ammonium ion \( \text{NH}_4^+ \) with the anions \( \text{CO}_3^{2-} \) and \( \text{SO}_4^{2-} \). For \( \text{(NH}_4)_2\text{CO}_3 \), two ammonium ions are needed to balance the charge of one carbonate ion. Similarly, for ammonium sulfate, \( \text{(NH}_4)_2\text{SO}_4 \), two ammonium ions are needed to balance the charge of one sulfate ion.

Step 2: Combining Nickel Cation with Anions

Next, we combine the nickel ion \( \text{Ni}^{2+} \) with the anions \( \text{CO}_3^{2-} \) and \( \text{SO}_4^{2-} \). Since each of these anions already balances with a \( \text{Ni}^{2+} \), the formulas are simply \( \text{NiCO}_3 \) and \( \text{NiSO}_4 \).

Key Concepts

Cation-Anion Combination

In the realm of inorganic chemistry, cations and anions play pivotal roles, quite like pieces of a puzzle that fit together to create a whole. A cation is a positively charged ion, while an anion carries a negative charge. These opposing charges attract each other, allowing them to combine and form neutral compounds.
Understanding the process involves some simple rules:

• The total positive charge from the cations must balance the total negative charge from the anions.
• If the charges aren't equal, we adjust the number of cations or anions to balance them.
• Common cations include metal ions like nickel (\( \mathrm{Ni}^{2+} \)), while ammonium (\( \mathrm{NH}_{4}^{+} \)) is a notable exception because it's a polyatomic ion.
• Anions often include nonmetals like the carbonate (\( \mathrm{CO}_{3}^{2-} \)) and sulfate (\( \mathrm{SO}_{4}^{2-} \)) ions.

By mastering these combinations, you can predict the formulas of many inorganic compounds.

Chemical Formulas

Chemical formulas are like the instructions for building compounds, showing which elements and how many of each form the compound. In ionic compounds, the formula reflects the smallest whole-number ratio of ions that results in a neutral charge.
For example:

• Ammonium carbonate is written as \((\text{NH}_4)_2\text{CO}_3\). This indicates that two ammonium ions are needed to balance one carbonate ion.
• For nickel carbonate, the formula \(\text{NiCO}_3\) shows a 1:1 ratio, as \( \text{Ni}^{2+} \) and \( \text{CO}_{3}^{2-} \) naturally balance each other out.
• Similarly, ammonium sulfate is \((\text{NH}_4)_2\text{SO}_4\), while nickel sulfate is \(\text{NiSO}_4\).

Crafting the right formula is pivotal in chemistry, ensuring each component balances others for stable compounds.

Ammonium Ion

The ammonium ion is a special kind of cation, which is unique because it's not made from metal. Instead, it consists of nitrogen and hydrogen atoms (\( \text{NH}_4^{+} \)). This polyatomic ion behaves like a single unit in chemical reactions.
Key points about ammonium ion:

• It carries a single positive charge, making it pair well with anions to form various compounds.
• In our example, it pairs with carbonate to form \((\text{NH}_4)_2\text{CO}_3\), needing two ammonium ions to balance the \( \text{CO}_{3}^{2-} \) anion.
• It also forms \((\text{NH}_4)_2\text{SO}_4\) with sulfate anions, again needing two ammonium ions to neutralize the charge.

Ammonium ions are versatile in forming many industrial and agricultural chemicals, demonstrating their importance and utility.

Nickel Ion

Nickel ions are derived from the metal nickel, carrying a charge of \( \text{Ni}^{2+} \). As a divalent cation, it combines readily with anions that have \( 2- \) charges to form stable compounds without needing multiple ions to balance the charge.
Some characteristics of nickel ions include:

• They readily form bonds with anions like carbonate and sulfate due to their matching charge of \( 2+ \).
• In compounds such as \(\text{NiCO}_3\) and \(\text{NiSO}_4\), the nickel ions and corresponding anions perfectly neutralize each other.
• Nickel compounds are widely used in electroplating, batteries, and catalysis, showcasing their chemical agility and industrial significance.

Understanding nickel ions helps us appreciate their role in forming diverse and useful compounds.