Question

Which of the following is not correct? (1) Calgon is an industrial name given to sodium hexametaphosphate, \(\mathrm{Na}_{2}\left[\mathrm{Na}_{4}\left(\mathrm{PO}_{3}\right)_{6}\right]\) (2) Permutit is hydrated sodium aluminosilicate, \(\mathrm{Na}_{2} \mathrm{Al}_{2} \mathrm{Si}_{2} \mathrm{O}_{8} \cdot \mathrm{xII}_{2} \mathrm{O}\) (3) The main component of the scale that accumulates in boilers is calcium carbonate. (4) Water softners are used to remove the impurities in water.

Short answer

Option 4 is not correct.

Step-by-step solution

- Analyze Option 1

Check if Calgon is an industrial name given to sodium hexametaphosphate, \(\mathrm{Na}_{2}\left[\mathrm{Na}_{4}\left(\mathrm{PO}_{3}\right)_{6}\right]\). Sodium hexametaphosphate is indeed marketed as Calgon, so option 1 is correct.

- Analyze Option 2

Verify if Permutit is hydrated sodium aluminosilicate, \(\mathrm{Na}_{2} \mathrm{Al}_{2} \mathrm{Si}_{2} \mathrm{O}_{8} \cdot \mathrm{xII}_{2}\mathrm{O}\). Permutit is actually a synthetic zeolite used in water softening, which is a hydrated sodium aluminosilicate. Therefore, option 2 is correct.

- Analyze Option 3

Determine if the main component of the scale that accumulates in boilers is calcium carbonate. The primary component of boiler scale is calcium carbonate, confirming that option 3 is correct.

- Analyze Option 4

Assess if water softeners are used to remove impurities in water. Water softeners primarily remove mineral ions such as calcium and magnesium that cause hardness in water. They do not remove all impurities, which makes option 4 incorrect.

Key concepts

Calgon

Calgon is a trade name for sodium hexametaphosphate, which has the chemical formula \(\mathrm{Na}_{2}\left[\mathrm{Na}_{4}\left(\mathrm{PO}_{3}\right)_{6}\right]\) This compound is crucial in water treatment because it helps prevent the formation of scale and corrosion in pipes and boilers by sequestering calcium and magnesium ions. Calgon achieves this by converting calcium and magnesium into soluble complexes, preventing them from depositing and forming hard, insoluble salts. It is widely used in industrial and home water systems to keep devices running smoothly.

Calgon is just one part of the broader category of chemicals known as water softeners. By understanding its role, you can better comprehend how water treatment works to protect and maintain the lifespan of plumbing systems and appliances.

Permutit

Permutit is a type of synthetic zeolite known as hydrated sodium aluminosilicate, with a chemical formula \(\mathrm{Na}_2 \mathrm{Al}_2 \mathrm{Si}_2 \mathrm{O}_8 \cdot \mathrm{xH}_2 \mathrm{O}\). This material is vital for water softening applications, where it exchanges sodium ions for calcium and magnesium ions present in hard water.

Permutit works through an ion-exchange process, which traps the hard water ions (calcium and magnesium) within its structure, replacing them with sodium ions. This exchange process reduces water hardness, which helps in preventing the formation of limescale on pipes and appliances. The cleaned water that results from this treatment is softer and more efficient for household and industrial use.

Since zeolites like Permutit can be regenerated repeatedly, they are a sustainable choice for effective water softening and treatment.

Boiler Scale

Boiler scale is a hard, crusty layer that forms on the interior surfaces of boilers due to the deposition of minerals from hard water, mainly composed of calcium carbonate (\(\mathrm{CaCO}_3\)). This scale is problematic because it acts as an insulator, reducing heat transfer efficiency and leading to increased fuel consumption and the risk of overheating or even failure of the boiler.

To combat boiler scale, the water fed into boilers is often treated to soften it, removing most of the calcium and magnesium ions responsible for the formation of scale. Regular maintenance, including descaling agents and monitoring water quality, is essential to keep boilers running efficiently and prolong their operational life.

Water Softeners

Water softeners are devices or substances used to treat hard water by removing or neutralizing its mineral content, primarily calcium and magnesium ions. This process prevents the formation of limescale and other mineral deposits in pipes, boilers, and appliances. There are various types of water softeners, including:

• Ion-exchange softeners: These systems replace hard minerals with sodium or potassium ions using resin beads.
• Salt-free softeners: These systems use potassium chloride instead of sodium chloride and convert minerals to a form that doesn't form scale.
• Magnetic/electronic softeners: These are less common and use magnetic fields to alter the minerals' properties so they don't adhere to surfaces.

Using water softeners not only helps in maintaining the efficiency of appliances and plumbing but also extends their lifespan and reduces maintenance costs. However, it's important to note that water softeners primarily target hardness minerals and do not remove other impurities like pathogens, chemicals, or organic matter.