Question

An element \(\mathrm{X}\) reacts with oxygen to form \(\mathrm{XO}_{2}\) and with chlorine to form \(\mathrm{XCl}_{4} \cdot \mathrm{XO}_{2}\) is a white solid that melts at high temperatures (above \(1000^{\circ} \mathrm{C}\) ). Under usual conditions, \(\mathrm{XCl}_{4}\) is a colorless liquid with a boiling point of \(58^{\circ} \mathrm{C}\). (a) \(\mathrm{XCl}_{4}\) reacts with water to form \(\mathrm{XO}_{2}\) and another product. What is the likely identity of the other product? (b) Do you think that element \(\mathrm{X}\) is a metal, nonmetal, or metalloid? (c) By using a sourcebook such as the CRC Handbook of Chemistry and Physics, try to determine the identity of element X.

Short answer

The other product formed when XCl4 reacts with water is hydrochloric acid (HCl). Element X is most likely a metalloid, and its identity is Silicon (Si).

Step-by-step solution

Reaction of XCl4 with water

We know that XCl4 reacts with water to form XO2 and another product. The reaction can be represented as follows: \[ XCl_4 + H_2O \rightarrow XO_2 + ? \] Step 2: Determine the other product

Identify the other product

As XCl4 is reacting with water, it will lose its chlorine atoms and form a product with hydrogen. Chlorine will react with hydrogen to form hydrochloric acid, hence the reaction product will be: \[ XCl_4 + 2H_2O \rightarrow XO_2 + 4HCl \] Step 3: Determine if element X is metal, non-metal, or metalloid

Identify the type of element

Given that XO2 is a white solid with a high melting point (above \(1000^{\circ} \mathrm{C}\)) and XCl4 is a colorless liquid with a low boiling point (\(58^{\circ} \mathrm{C}\)), these properties suggest that element X is a non-metal. Usually, metal oxides are composed of metal and oxygen and have a high melting point, while metal chlorides are generally solids with high boiling points. In this case, the given properties of XO2 and XCl4 do not comply with those of typical metal compounds. Step 4: Identify the element X

Find the identity of element X

Using a reference source like the CRC Handbook of Chemistry and Physics, we can look for an element that forms a compound with the formula XO2, which has a high melting point, and a compound with the formula XCl4, which is a colorless liquid with a low boiling point. Based on these properties and after searching through a reference source, we can deduce that the element X is likely to be Silicon (Si). So, to conclude: a) The other product formed when XCl4 reacts with water is hydrochloric acid (HCl). b) The element X is most likely a metalloid. c) The identity of the element X is Silicon (Si).

Key concepts

Silicon Compounds

Silicon, a widely used element in the tech industry, forms various compounds through its chemical reactions. When silicon reacts with oxygen, it forms silicon dioxide (\( \text{SiO}_2 \)), a vital material in the production of glass and ceramics.
Silicon also reacts with chlorine to produce silicon tetrachloride (\( \text{SiCl}_4 \)). This liquid compound is often used in the process of silicon purification and in making other silicon-based chemicals.
Silicon compounds have unique properties that make them irreplaceable in electronics, thanks to silicon's role as a semiconductor.

• Silicon Dioxide (\( \text{SiO}_2 \)): Forms a white solid known for its high melting point; it is the primary component in sand and quartz.
• Silicon Tetrachloride (\( \text{SiCl}_4 \)): A colorless liquid crucial in the manufacture of optical fibers and silica aerogels.

Silicon's ability to form stable compounds with both metals and non-metals exemplifies its versatility and importance in industrial applications.

Non-metal Properties

Elements are classified based on their physical and chemical properties. Non-metals possess distinctive characteristics when compared to metals. They often occur in various states of matter at room temperature and generally have lower densities than metals.
Non-metals tend to have higher ionization energies and electronegativities. This means they are less likely to lose electrons and more likely to gain them during chemical reactions.

• Physical Properties: Non-metals can be gases, liquids or solids at room temperature. They are typically brittle when solid and lack metallic luster.
• Chemical Properties: Non-metals have a tendency to form negative ions in reactions, and they generally form covalent bonds when reacting with other non-metals.

These characteristics allow non-metals to play essential roles in life and technology, particularly in biological systems and chemical processes.

Metalloid Characteristics

Metalloids, such as silicon, showcase properties that are intermediate between metals and non-metals. These elements exhibit a fine balance of characteristics, making them unique in the periodic table. The properties of metalloids are influenced by their ability to form compounds with various elements.

• Electrical Conductivity: Metalloids behave as semiconductors, showing increased conductivity with higher temperatures.
• Appearance and Hardness: They generally have metallic luster but differ from metals by being brittle.

The semiconductor nature of metalloids makes them invaluable in modern electronics, such as computer chips and solar cells.
Metalloids can react with both metals and non-metals, forming a diversity of compounds. Their ability to merge the properties of metals and non-metals ensures they have roles in electronics, optics, and materials science.
Silicon, being a key metalloid, is an excellent example of these properties, allowing us to harness its unique electronic characteristics for technological advancements.