Question

Salt cake is anhydrous (1) Sodium carbonate (2) Sodium sulphatc (3) Sodium tetraborate (4) Sodium nitratc

Short answer

Sodium sulfate

Step-by-step solution

Identify the Definition

Salt cake is commonly known as a chemical term used to refer to a specific anhydrous compound.

Recognize the Chemical Names

Read through the given compounds: Sodium carbonate, Sodium sulfate, Sodium tetraborate, and Sodium nitrate.

Match the Compound with Salt Cake

Salt cake is the industrial name primarily used for Sodium sulfate, which is anhydrous (without water).

Key concepts

Sodium sulfate

Sodium sulfate is a white crystalline solid commonly referred to as salt cake, Glauber's salt, or mirabilite in its natural form. It has the chemical formula Na₂SO₄. This compound is highly soluble in water and is frequently used in various industrial applications.

Sodium sulfate is produced both naturally and synthetically. Naturally, it forms from sedimentary mineral deposits or as a byproduct of chemical processes, like the production of hydrochloric acid. Industrially, it’s harvested during the production of chemicals such as sodium dichromate.

Sodium sulfate is primarily used in the manufacturing of detergents and in the Kraft process of paper pulping. It also plays a role in textile manufacturing, from dyeing to finishing fabrics, and is even found in the glass industry as a fining agent.

Sodium sulfate is highly regarded for its stable, non-toxic nature, making it very reliable and safe for use across a variety of applications.

Anhydrous compounds

Anhydrous compounds are substances that contain no water molecules. The term ‘anhydrous’ specifically means 'without water'. These compounds can either naturally lack water or have had the water removed through various drying processes.

One popular method of removing water from compounds is through heating, which evaporates the water content, leaving behind just the anhydrous form. An example is when heating hydrated copper(II) sulfate (blue crystals) to yield anhydrous copper(II) sulfate (white powder).

In industry, anhydrous compounds are preferred in reactions where water could be a contaminant or interfere with the reaction. They are also used as drying agents (desiccants) to maintain a dry environment in packaging or reactions.

Sodium sulfate in its anhydrous form (Na₂SO₄) is referred to as thenardite. When mixed with ten water molecules, it becomes Glauber's salt (Na₂SO₄·10H₂O). The capacity to transition between these forms depending on environmental humidity makes it versatile for various applications.

Chemical names

Chemical names are systematic ways of referring to chemical substances. These names, provided by international bodies like IUPAC (International Union of Pure and Applied Chemistry), follow specific rules to ensure uniformity and clarity.

Common names, like salt cake, can vary by region or industry. However, the IUPAC name provides a universal nomenclature. For example, salt cake refers to anhydrous sodium sulfate, which clearly indicates its chemical composition (Na₂SO₄).

Some rules in chemical naming include:

• Using prefixes to indicate the number of atoms (e.g., di-, tri-).
• Employing suffixes that show the type of chemical bonds or functional groups present (e.g., -ate for salts of acids).
• Indicating the oxidation states of elements, especially in transition metals (e.g., iron(III) chloride for FeCl₃).

Understanding chemical names helps in quickly recognizing compound composition, potential applications, and hazards. It ensures everyone speaks the same chemical language, whether in academic, industrial, or regulatory settings.