Question

Write the formula for the polyatomic ion in each of the following and name each compound: a. KOH b. \(\mathrm{NaNO}_{3}\) c. \(\mathrm{Au}_{2} \mathrm{CO}_{3}\) d. \(\mathrm{NaHCO}_{3}\) e. \(\mathrm{BaSO}_{4}\)

Short answer

KOH: potassium hydroxide (OH⁻); NaNO₃: sodium nitrate (NO₃⁻); Au₂CO₃: gold(I) carbonate (CO₃²⁻); NaHCO₃: sodium bicarbonate (HCO₃⁻); BaSO₄: barium sulfate (SO₄²⁻).

Step-by-step solution

- Determine the Polyatomic Ion in KOH

Identify the polyatomic ion in KOH. The compound consists of potassium (K) and the hydroxide ion (OH⁻). The polyatomic ion is OH⁻ (hydroxide).

- Name the Compound KOH

The name of KOH is potassium hydroxide, combining the name of the cation (potassium) with the name of the polyatomic ion (hydroxide).

- Determine the Polyatomic Ion in NaNO₃

Identify the polyatomic ion in NaNO₃. The compound consists of sodium (Na) and the nitrate ion (NO₃⁻). The polyatomic ion is NO₃⁻ (nitrate).

- Name the Compound NaNO₃

The name of NaNO₃ is sodium nitrate, combining the name of the cation (sodium) with the name of the polyatomic ion (nitrate).

- Determine the Polyatomic Ion in Au₂CO₃

Identify the polyatomic ion in Au₂CO₃. The compound consists of gold (Au) and the carbonate ion (CO₃²⁻). The polyatomic ion is CO₃²⁻ (carbonate).

- Name the Compound Au₂CO₃

The name of Au₂CO₃ is gold(I) carbonate, where the I represents the oxidation state of gold, combining the name of the cation (gold) with the name of the polyatomic ion (carbonate).

- Determine the Polyatomic Ion in NaHCO₃

Identify the polyatomic ion in NaHCO₃. The compound consists of sodium (Na) and the hydrogen carbonate ion (HCO₃⁻). The polyatomic ion is HCO₃⁻ (hydrogen carbonate).

- Name the Compound NaHCO₃

The name of NaHCO₃ is sodium bicarbonate, combining the name of the cation (sodium) with the name of the polyatomic ion (bicarbonate).

- Determine the Polyatomic Ion in BaSO₄

Identify the polyatomic ion in BaSO₄. The compound consists of barium (Ba) and the sulfate ion (SO₄²⁻). The polyatomic ion is SO₄²⁻ (sulfate).

- Name the Compound BaSO₄

The name of BaSO₄ is barium sulfate, combining the name of the cation (barium) with the name of the polyatomic ion (sulfate).

Key concepts

potassium hydroxide

Potassium hydroxide, also known by its chemical formula KOH, is composed of two different parts: the cation potassium (K) and the polyatomic ion hydroxide (OH⁻). When naming this compound, you first state the name of the cation (potassium) and then the polyatomic ion (hydroxide). Potassium hydroxide is commonly used in various industrial processes, such as soap making and as a strong base in chemistry labs. Always remember to handle it with care as it is highly caustic and can cause severe burns upon contact with skin.

sodium nitrate

Sodium nitrate is an important inorganic compound with the chemical formula \( \text{NaNO}_{3} \). It consists of the cation sodium (Na) and the polyatomic ion nitrate (NO₃⁻). When naming this compound, combine the cation (sodium) and the polyatomic ion (nitrate) to form sodium nitrate. This compound is frequently used in fertilizers, food preservation, and even fireworks. The nitrate ion itself contains one nitrogen atom and three oxygen atoms, giving it the chemical character needed for these applications.

gold(I) carbonate

Gold(I) carbonate, represented by the chemical formula \( \text{Au}_{2} \text{CO}_{3} \), includes two gold (Au) atoms and one carbonate (CO₃²⁻) ion. The (I) in the name indicates the oxidation state +1 of gold in this particular compound. Thus, when naming, state the cation first, including its oxidation state, followed by the polyatomic ion: gold(I) carbonate. This compound is significant in the field of material science and chemistry. Carbonate itself is a polyatomic ion composed of one carbon atom and three oxygen atoms, carrying a -2 charge.

sodium bicarbonate

Commonly known as baking soda, sodium bicarbonate's chemical formula is \( \text{NaHCO}_{3} \). It comprises the cation sodium (Na) and the polyatomic ion hydrogen carbonate (HCO₃⁻), which is also referred to as bicarbonate. When identifying this compound, you name it by combining the cation and the polyatomic ion: sodium bicarbonate. This versatile compound is used for baking, cleaning, neutralizing acids, and even in medical applications to treat acid indigestion. The hydrogen carbonate ion contains one hydrogen atom, one carbon atom, and three oxygen atoms, making it unique in its functionality.

barium sulfate

Barium sulfate is a chemical compound with the formula \( \text{BaSO}_{4} \), combining barium (Ba) and the polyatomic ion sulfate (SO₄²⁻). When naming this compound, you start with the cation barium, followed by the polyatomic ion sulfate. Barium sulfate has significant use in the medical field as a radiocontrast agent for X-ray imaging and other diagnostic procedures. The sulfate ion contains one sulfur atom surrounded by four oxygen atoms, carrying an overall charge of -2. This structure contributes to its stability and insolubility in water.