Question

Which on heating with NaOII solution gives inflammable gas? (1) $\mathrm{Zn}$ (2) $\mathrm{P}$ (3) $\mathrm{S}\mathrm{i}$ (4) $\mathrm{\Lambda }11$

Short answer

Li (Lithium) produces inflammable gas with NaOH solution.

Step-by-step solution

- Identify Reactants

Determine which substances will react with NaOH (sodium hydroxide) to produce a gas. The options given are Zn (zinc), P (phosphorus), Si (silicon), and L11 (likely a typo, assuming lithium Li).

- Analyze Chemical Reactions

Consider each element's reaction with sodium hydroxide solution (NaOH):1. $\text{Zn}+\text{NaOH}\to {\text{Zn(OH)}}_2+{\text{H}}_2$2. Phosphorus generally does not react with NaOH to produce a gas.3. Silicon does not react with NaOH to give a gas.4. $\text{Li}+{\text{H}}_{2}O(inNaOHsolution)\to \text{LiOH}+{\text{H}}_2$

- Determine the Inflammable Gas Released

Recognize that hydrogen gas (${\text{H}}_2$) is released when Zn or Li reacts with NaOH. Hydrogen gas is inflammable.

- Compare Reaction Characteristics

Compare the likelihood and prominence of the reactions. While both Zn and Li can produce hydrogen gas, Li is more reactive and consistently produces it when reacting with water or NaOH.

- Select the Correct Answer

Identify that the element most likely to release an inflammable gas when heated with NaOH is lithium (Li).

Key concepts

Reactivity of Elements

In chemistry, the reactivity of elements is a fundamental concept that helps us understand how substances interact with one another. Some elements are more reactive, meaning they readily undergo chemical reactions, while others are less reactive. The reactivity of an element depends on its atomic structure and the ease with which it can gain, lose, or share electrons.

Zinc (Zn) and lithium (Li) are two elements that react with sodium hydroxide (NaOH). Zinc reacts to form zinc hydroxide and hydrogen gas, a moderately reactive process. The chemical equation is $\text{Zn}+2\text{NaOH}\to \text{Zn(OH)}\text{2}+{\text{H}}_2$.

On the other hand, lithium reacts much more vigorously. Lithium's reaction with water, even in a sodium hydroxide solution, is highly exothermic, producing lithium hydroxide and releasing hydrogen gas. The reaction is: $\text{Li}+{\text{H}}_2\text{O}\to \text{LiOH}+{\text{H}}_2$.

This explains why lithium consistently produces inflammable hydrogen gas, making it more reactive than zinc, phosphorus (P), and silicon (Si) in these conditions.

Production of Hydrogen Gas

Hydrogen gas (\text{H}_2) is commonly produced in chemical reactions involving metals and water or bases like sodium hydroxide. This gas is known for its inflammable properties and its use in various industries such as fuel cells and manufacturing.

When a metal like zinc or lithium reacts with sodium hydroxide, it displaces hydrogen atoms from water molecules, forming hydrogen gas. For zinc, the equation is: $\text{Zn}+2\text{NaOH}\to \text{Zn(OH)}\text{2}+{\text{H}}_2$.

Similarly, lithium reacts with water in the NaOH solution to produce hydrogen gas: $\text{Li}+{\text{H}}_2\text{O}\to \text{LiOH}+{\text{H}}_2$.

This production is significant because hydrogen gas is a clean energy source. However, it is also highly flammable, requiring careful handling and storage. Recognizing which elements easily produce hydrogen gas helps scientists and engineers harness this property safely and effectively.

Properties of Metals

Metals are characterized by their unique properties that make them integral to countless applications. Some of the key properties of metals include:

• Conductivity: Metals like copper and aluminum are excellent conductors of electricity and heat.
• Malleability: Many metals can be hammered or rolled into thin sheets without breaking.
• Ductility: Metals can be drawn into wires, which is particularly useful in electrical wiring and cabling.
• Reactivity: As highlighted in this exercise, metals can react with acids, bases, and water to produce gases and other compounds.

When it comes to reactivity, metals like lithium are highly reactive, especially with water and bases, leading to the production of hydrogen gas. This differs from less reactive metals such as phosphorus and silicon, which do not react readily or produce gases under similar conditions.

Understanding the properties of metals, including reactivity, is crucial in fields like chemistry, material science, and engineering. This knowledge allows for the appropriate selection of metals for specific applications, ensuring safety and efficacy in their use.