Problem 134 - Chemistry Matter and Change

Question

Sodium chloride is not the only ionic compound that forms from sea water. Identify four other compounds that could be formed that contain the sodium ion. Write both the formula and the name for each compound

Step-by-Step Solution

Answer

Four other sodium-containing ionic compounds formed from seawater are: 1. Sodium sulfate (Na₂SO₄) 2. Sodium carbonate (Na₂CO₃) 3. Sodium bicarbonate (NaHCO₃) 4. Sodium phosphate (Na₃PO₄)

Step 1: Identify ions in seawater

Seawater is a complex solution containing a variety of dissolved ions, mainly cations, and anions. Some of the most common ions found in seawater, besides sodium, are chloride (Cl-), sulfate (SO4²-), magnesium (Mg²+), calcium (Ca²+), and potassium (K+).

Step 2: Identify possible ionic compounds with sodium ion

Considering the other common ions in seawater, we can combine the sodium ion (Na+) with these anions to create other ionic compounds.

Step 3: Compound 1

A possible compound is Sodium sulfate, which forms when sodium (Na+) ion combines with sulfate (SO4²-) ion: Na⁺ + SO₄²⁻ → Na₂SO₄ Name: Sodium sulfate Formula: Na₂SO₄

Step 4: Compound 2

A possible compound is Sodium carbonate, which forms when sodium (Na+) ion combines with carbonate (CO₃²⁻) ion: Na⁺ + CO₃²⁻ → Na₂CO₃ Name: Sodium carbonate Formula: Na₂CO₃

Step 5: Compound 3

A possible compound is Sodium bicarbonate, which forms when sodium (Na+) ion combines with bicarbonate (HCO₃⁻) ion: Na⁺ + HCO₃⁻ → NaHCO₃ Name: Sodium bicarbonate Formula: NaHCO₃

Step 6: Compound 4

A possible compound is Sodium phosphate, which forms when sodium (Na+) ion combines with phosphate (PO₄³⁻) ion: 3Na⁺ + PO₄³⁻ → Na₃PO₄ Name: Sodium phosphate Formula: Na₃PO₄ These are four other compounds that could be formed from seawater containing the sodium ion.

Key Concepts

Sodium Ion

The sodium ion is a positively charged particle, denoted as Na⁺, that plays a crucial role in the chemistry of seawater. It is derived from sodium (Na) atoms losing a single electron, which gives the ion its positive charge. Sodium ions are abundant in seawater and are essential for maintaining various biological functions in marine life. In the context of forming ionic compounds, sodium ions often combine with negatively charged ions (anions) to create stable compounds. This ability to form compounds is why sodium ions are found in a wide range of substances in the ocean.

Seawater Chemistry

Seawater chemistry is defined by the complex interactions between a vast array of dissolved ions. These ions are categorized as either cations, which carry a positive charge like sodium (\(\text{Na}^+\)), or anions, which carry a negative charge, such as chloride (\(\text{Cl}^-\)) and sulfate (\(\text{SO}_4^{2-}\)).
In seawater, these ions are ever-present due to the natural processes that erode minerals and rocks and wash them into the sea. These dissolved ions are not only crucial for marine ecosystems but also form various common compounds. Sodium chloride (\(\text{NaCl}\)) is the most familiar of them, but many others form through the combination of sodium with different anions available in the seawater.

• Chloride: \(\text{Cl}^-\)
• Sulfate: \(\text{SO}_4^{2-}\)
• Bicarbonate: \(\text{HCO}_3^-\)
• Phosphate: \(\text{PO}_4^{3-}\)

These compounds, once formed, contribute to the various physical and chemical properties of seawater. Understanding these interactions helps in comprehending marine life’s adaptations and the ocean's overall chemistry.

Chemical Formulas

Chemical formulas are representations of the elements in a compound and how many of each atom are present. For ionic compounds formed by sodium ions, the chemical formula indicates which ions have combined and in what ratios. These formulas are crucial because they give insight into the compound's composition.
For example, in sodium sulfate (\(\text{Na}_2\text{SO}_4\)), the formula reveals that two sodium ions combine with one sulfate ion to create the compound. Similarly, sodium carbonate (\(\text{Na}_2\text{CO}_3\)) consists of two sodium ions paired with one carbonate ion.

• Sodium sulfate: \(\text{Na}_2\text{SO}_4\)
• Sodium carbonate: \(\text{Na}_2\text{CO}_3\)
• Sodium bicarbonate: \(\text{NaHCO}_3\)
• Sodium phosphate: \(\text{Na}_3\text{PO}_4\)

Each formula follows the principle of electrical neutrality where the total positive charge equals the total negative charge, ensuring the compound stays stable.

Ionic Bonding

Ionic bonding is a type of chemical bond where atoms transfer electrons to achieve a full outer shell, resulting in positively and negatively charged ions. In sodium ions' case, the transfer of one electron results in a \(\text{Na}^+\) positive charge.
These sodium ions then form ionic bonds with anions, like \(\text{Cl}^-\) and \(\text{SO}_4^{2-}\), creating compounds through an electrostatic attraction between opposite charges. This bond is strong and gives ionic compounds their characteristic high melting and boiling points.

• Electron transfer leads to full electron shells.
• Oppositely charged ions attract.
• Strong bonds imply high stability.

Ionic bonds' strength is one reason why ionic compounds like sodium chloride and sodium sulfate are stable in water, making them prevalent in seawater chemistry.