Question

What is the phase of the standard states of the following elements and compounds? (a) \(\mathrm{NH}_{3}\) (b) \(\mathrm{Fe}\) (c) \(\mathrm{N}_{2}\) (d) \(\mathrm{Br}_{2}\)

Short answer

(a) Gas, (b) Solid, (c) Gas, (d) Liquid.

Step-by-step solution

Determine the Phase of NH3

Ammonia, \(\mathrm{NH}_{3}\), is most commonly found as a gas at room temperature. It has a boiling point of -33.34 °C, which makes it a gas under standard conditions (25 °C and 1 atm). Thus, the phase of \(\mathrm{NH}_{3}\) in its standard state is gas.

Determine the Phase of Fe

Iron, \(\mathrm{Fe}\), is a solid under standard conditions. Metals are generally solid at room temperature, with the only exception among common elements being mercury. Therefore, the phase of \(\mathrm{Fe}\) in its standard state is solid.

Determine the Phase of N2

Nitrogen, \(\mathrm{N}_{2}\), is a diatomic molecule present mainly in the atmosphere. It is a gas at room temperature. Consequently, the phase of \(\mathrm{N}_{2}\) in its standard state is gas.

Determine the Phase of Br2

Bromine, \(\mathrm{Br}_{2}\), is unique among the halogens as it is a liquid at room temperature. It has a higher boiling point than room temperature, making it a liquid under standard conditions. Hence, the phase of \(\mathrm{Br}_{2}\) in its standard state is liquid.

Key concepts

Phase of Ammonia

Ammonia (\( \mathrm{NH}_3 \)) is a compound that you might have encountered in household cleaning products or fertilizers. At room temperature, which is approximately 25°C, ammonia is typically found in its gaseous form. This is due to its relatively low boiling point of -33.34°C, making it a gas under standard temperature and pressure conditions.

Ammonia consists of nitrogen and hydrogen atoms, and its molecular structure contributes to its state at room temperature.

• Ammonia is very soluble in water and can be easily liquefied with pressure.
• It has a pungent smell and can be hazardous in higher concentrations.

Understanding the phase of ammonia is crucial for applications like refrigeration, where it can be used as a refrigerant due to its heat absorption properties.

Phase of Iron

Iron (\( \mathrm{Fe} \)) is one of the most common metals and has a significant presence in everyday life, found in everything from infrastructure to kitchen utensils. At room temperature, iron exists in a solid state.

This is typical for most metals, as they generally have solid phases due to strong metallic bonds which hold atoms together tightly.

• Iron has a melting point of approximately 1538°C.
• Its solid form is characterized by its hardness and strength, making it ideal for construction and manufacturing.
• Under extreme heating, iron will transition to a liquid form, which is key in processes like smelting.

Knowing the phase of iron helps in fields like metallurgy and materials science, where its thermal properties and mechanical strength are of interest.

Phase of Nitrogen

Nitrogen (\( \mathrm{N}_2 \)) is a diatomic molecule that makes up about 78% of Earth's atmosphere. At room temperature, nitrogen is found in a gaseous state.

This is because nitrogen has a low boiling point of -195.79°C, which means it remains a gas under standard atmospheric conditions.

• This gaseous form is odorless and colorless, making it an ideal medium in protecting food products from oxidation when packaged.
• Nitrogen gas is also inert, which plays a crucial role in maintaining the stability of the atmosphere.
• In its liquid form, obtained by cooling the gas, nitrogen is used in various applications, such as cryogenics and food preservation.

The knowledge of nitrogen's phase is essential in diverse areas, from respiratory applications to industrial manufacturing.

Phase of Bromine

Bromine (\( \mathrm{Br}_2 \)) stands out among the halogens as one of the only elements that is liquid at room temperature. This phase distinction makes bromine quite unique compared to other non-metals.

At standard conditions, it remains liquid because its boiling point is higher than room temperature, at about 59°C.

• Bromine has a reddish-brown color in its liquid state and emits a strong odor.
• It is less volatile compared to other halogens, which is why it doesn't become gaseous as readily at room temperature.
• Liquid bromine is reactive and is used in the synthesis of a wide range of bromine compounds.

Understanding bromine's liquid phase helps chemists and industries in safely handling and utilizing this element effectively.