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 \(\mathrm{SO}_{4}^{2-}\).

Short answer

Possible compounds: \((\mathrm{NH}_4)_2\mathrm{CO}_3\), \((\mathrm{NH}_4)_2\mathrm{SO}_4\), \(\mathrm{NiCO}_3\), \(\mathrm{NiSO}_4\).

Step-by-step solution

Identify Cations and Anions

We are given two cations, ammonium \(\mathrm{NH}_4^+\) and nickel \(\mathrm{Ni}^{2+}\), and two anions, carbonate \(\mathrm{CO}_3^{2-}\) and sulfate \(\mathrm{SO}_4^{2-}\). Our task is to form chemical compounds by pairing each cation with each anion.

Combine Ammonium \(\mathrm{NH}_4^+\) with Anions

- Combine \(\mathrm{NH}_4^+\) with \(\mathrm{CO}_3^{2-}\):Add two ammonium ions to balance the charge of one carbonate ion: \((\mathrm{NH}_4)_2\mathrm{CO}_3\).- Combine \(\mathrm{NH}_4^+\) with \(\mathrm{SO}_4^{2-}\):Add two ammonium ions to balance the charge of one sulfate ion: \((\mathrm{NH}_4)_2\mathrm{SO}_4\).

Combine Nickel \(\mathrm{Ni}^{2+}\) with Anions

- Combine \(\mathrm{Ni}^{2+}\) with \(\mathrm{CO}_3^{2-}\):Nickel carbonate does not need extra balancing of ions: \(\mathrm{NiCO}_3\).- Combine \(\mathrm{Ni}^{2+}\) with \(\mathrm{SO}_4^{2-}\):Nickel sulfate does not need extra balancing of ions: \(\mathrm{NiSO}_4\).

Summary of Formulas

The four possible compounds formed are:- \((\mathrm{NH}_4)_2\mathrm{CO}_3\)- \((\mathrm{NH}_4)_2\mathrm{SO}_4\)- \(\mathrm{NiCO}_3\)- \(\mathrm{NiSO}_4\)

Key concepts

Cation-Anion Combination

Combining cations and anions is like building a bridge—a connection must exist between positive and negative. In chemistry, cations are positively charged ions, and anions are their negatively charged counterparts. This attraction lies at the heart of forming ionic compounds. When you combine them, think of a pair of puzzle pieces that fit perfectly because of their complementary shapes. In this exercise, we have two cations:

• Ammonium ion \(\mathrm{NH}_4^+\)
• Nickel(II) ion \(\mathrm{Ni}^{2+}\)

and two anions:

• Carbonate ion \(\mathrm{CO}_3^{2-}\)
• Sulfate ion \(\mathrm{SO}_4^{2-}\)

Each cation can pair with each anion to form a distinct compound. The key is to make sure their charges balance, ensuring the overall neutrality of the compound.

Chemical Formulas

Writing chemical formulas is like writing a recipe—it shows the ingredients and their amounts but in chemical terms. A formula provides crucial information about which elements or ions are present and in what ratios they combine. For example, when forming \((\mathrm{NH}_4)_2\mathrm{CO}_3\), we have:

• Two ammonium ions \(\mathrm{NH}_4^+\)
• One carbonate ion \(\mathrm{CO}_3^{2-}\)

This formula indicates that twice as many ammonium ions are needed to balance the single carbonate ion's charge. The strategy stays the same regardless of the ions involved: balance the charges by adjusting the coefficients in the formula. This ensures that the net charge of the compound equals zero. Writing these formulas correctly is crucial for identifying compounds and understanding their behavior in various reactions.

Ionic Compounds

Ionic compounds result from the mutual attraction between cations and anions. They form crystalline structures, which are stable arrangements held together by the electrostatic force between opposing charges. Imagine tiny magnets aligning themselves in order because of how they attract each other. In our case, when ammonium pairs up with sulfate or nickel with carbonate, these structures form. Examples we formed include:

• Ammonium sulfate \((\mathrm{NH}_4)_2\mathrm{SO}_4\)
• Nickel carbonate \(\mathrm{NiCO}_3\)

These compounds typically have high melting and boiling points due to the strength of these ionic bonds. In solution, these compounds readily dissolve, allowing the ions to move freely and conduct electricity. This makes ionic compounds quite essential in various applications, from industrial processes to powering your mobile devices via batteries.

Charge Balancing

Charge balancing is the secret sauce behind forming stable ionic compounds. It involves ensuring that the total positive charges from the cations equal the total negative charges from the anions in a compound. For example, consider the combination of \(\mathrm{NH}_4^+\) and \(\mathrm{CO}_3^{2-}\):

• Each \(\mathrm{NH}_4^+\) ion carries a \(+1\) charge.
• The \(\mathrm{CO}_3^{2-}\) ion carries a \(-2\) charge.

By using two \(\mathrm{NH}_4^+\) ions, their combined \(+2\) charge perfectly balances the \(-2\) from the carbonate, resulting in \((\mathrm{NH}_4)_2\mathrm{CO}_3\). For nickel sulfate, \(\mathrm{NiSO}_4\), both Ni and SO₄ have 2- charges, so only one of each is required. Effective charge balancing ensures the compound is electrically neutral, which is crucial for its stability and reactivity.