Problem 72 - A Complete Resource Book in Chemistry for JEE Main

Question

Aluminium vessles should not be washed with materials containing washing soda because (a) washing soda reacts with aluminum to form insoluble aluminium oxide (b) washing soda reacts with aluminium to form soluble aluminate. (c) washing soda is expensive (d) washing soda is easily decomposed

Step-by-Step Solution

Answer

(b) washing soda reacts with aluminium to form soluble aluminate.

Step 1: Identify the Chemical Reaction

Aluminum reacts with washing soda (sodium carbonate) which is a chemical reaction of aluminum with an alkaline substance.

Step 2: Find the Result of the Reaction

When aluminum reacts with sodium carbonate, a chemical reaction occurs that involves the formation of a soluble compound known as sodium aluminate and the release of carbon dioxide gas.

Step 3: Understand the Property of the Product

Sodium aluminate is a soluble compound, meaning it can dissolve in water, unlike aluminum oxide which is insoluble.

Step 4: Determine the Correct Option

Since aluminum reacts with washing soda to form sodium aluminate, and considering the solubility and expense factors, option (b) 'washing soda reacts with aluminium to form soluble aluminate' is the correct answer.

Key Concepts

Chemical Reactions

Chemical reactions are processes where one or more substances are transformed into new substances. In the case of aluminum and sodium carbonate, this transformation involves a reaction with an alkaline substance. This specific type of chemical reaction happens when aluminum comes into contact with sodium carbonate, leading to the formation of new compounds.

The transformation can typically involve the breaking and formation of chemical bonds, observed as changes in matter such as gas production or formation of precipitates. During the reaction between aluminum and sodium carbonate, carbon dioxide gas is released. The fizzing or bubbling you might see is due to this gas escaping into the air.

Other evidence of chemical reactions include color changes, temperature changes, or emission of light. Although not all of these changes may be visually or tactilely perceptible, they are integral outcomes of the dynamic process involving aluminum chemistry.

Understanding these reactions is crucial in predicting how substances will interact under various conditions, allowing us to take necessary precautions.

Sodium Carbonate

Sodium carbonate, commonly known as washing soda, is a white, water-soluble compound. It is used in a range of cleaning products due to its alkalinity, helping to soften water and allowing detergents to work more effectively.

Chemically, washing soda is represented by the formula \( \text{Na}_2\text{CO}_3 \). It reacts readily with substances like aluminum because of its alkaline nature. In the presence of moisture, sodium carbonate can act as a drying agent, absorbing water molecules.

In its interaction with metals, particularly aluminum, sodium carbonate initiates a reaction leading to the formation of sodium aluminate. This interaction underscores the reason why using washing soda on aluminum vessels can lead to undesirable results due to substance transformation.

Using washing soda on aluminum is therefore not advisable if one wishes to maintain the integrity of aluminum objects. Its reactive properties highlight the importance of selecting appropriate cleaning agents depending on the material in question.

Soluble Aluminates

Soluble aluminates are compounds in which aluminum combines with other elements to form a solution that can dissolve in water. When aluminum reacts with sodium carbonate, it forms a compound called sodium aluminate, expressed chemically as \( \text{NaAlO}_2 \).

Aluminates are significant in various industrial processes because of their solubility in water. This property leads to several functional applications, such as in water treatment and the production of certain alumina-based materials.

The formation of soluble aluminate through the reaction of aluminum and washing soda is a classic example of how chemical reactions can alter the substance properties dramatically. In practical terms, using washing soda with aluminum converts the metal into a form that combines with water rather than maintaining its solid state.

This characteristic underscores the need for understanding the chemistry behind products that are commonly encountered in both household and industrial settings.