Question

An element \(X\) reacts with oxygen to form \(\mathrm{XO}_{2}\) and with chlorine to form \(\mathrm{XCl}_{4} . \mathrm{XO}_{2}\) is a white solid that melts at high temperatures (above \(\left.1000^{\circ} \mathrm{C}\right)\). 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? Explain. (c) \(\mathrm{By}\) using a sourcebook such as the CRC Handbook of Chemistry and Physics, try to determine the identity of element \(\mathrm{X}\).

Short answer

a) The other product when XCl₄ reacts with water is hydrochloric acid (HCl). b) Element X is a metalloid. c) Element X is likely Silicon (Si).

Step-by-step solution

(Step 1: Analyzing the Reaction of XCl₄ with water)

Let's first analyze the reaction that takes place when XCl₄ reacts with water: \[XCl_{4} + H_{2}O \rightarrow XO_{2} + ?\] From the given information, it is clear that XO₂ is formed. To find the other product, we balance the number of each atom. We can see that there are four Cl atoms on the left of the equation and none on the right side. Thus, the remaining product should have four Cl atoms. Also, since there are 2 hydrogen atoms on the left side, they need to be present in the other product.

(Step 2: Identifying other product in XCl₄+H₂O reaction)

Since the reaction involves XO₂ and water, a typical reaction that takes place between a compound and water is an acid-base reaction. In this reaction, water acts as a base and donates two protons. A common byproduct of such reactions is a compound containing H and Cl ions. In this case, with four Cl atoms and two H atoms, our product is most likely HCl and in a balanced form, we will have 2 moles of HCl. The balanced reaction is: \[XCl_{4} + 2H_{2}O \rightarrow XO_{2} + 4HCl\] So, the likely identity of the other product is hydrochloric acid (HCl).

(Step 3: Identifying if X is a metal, nonmetal or metalloid)

Now, let's determine if element X is a metal, nonmetal, or metalloid. The following points give us clues about the nature of element X: 1. XO₂ is a white solid with a high melting point, which indicates that element X might have ionic bonds with oxygen, thus meaning it has a tendency to lose electrons (a property of metals). 2. XCl₄ is a colorless liquid and has a low boiling point, which indicates polar covalent bonds, typically a characteristic of nonmetals and metalloids. Considering both points, it is difficult to give a clear-cut decision if X is a metal, nonmetal, or metalloid just by these properties. However, since X forms an ionic compound (XO₂) and a covalent compound (XCl₄), it is probably a metalloid as metalloids tend to show properties of both metals and nonmetals.

(Step 4: Using a reference source to identify element X)

To identify element X, we can consult a sourcebook such as the CRC Handbook of Chemistry and Physics. Given the information about the two compounds XO₂ and XCl₄, as well as considering that X is likely a metalloid, there is a good chance that element X is Silicon (Si). SiO₂ is a white, high melting point solid, and SiCl₄ is a colorless liquid with a boiling point of 57.6°C, which is close to the boiling point given in the problem. Also, when SiCl₄ reacts with water, it forms SiO₂ and HCl as predicted in our first step. Therefore, element X is likely Silicon (Si). In summary: a) The likely identity of the other product when XCl₄ reacts with water is hydrochloric acid (HCl). b) Element X is a metalloid. c) Using a sourcebook such as the CRC Handbook of Chemistry and Physics, element X is likely Silicon (Si).

Key concepts

Balanced Chemical Reactions

In the world of chemistry, balanced chemical reactions are fundamental. A balanced chemical equation ensures that the law of conservation of mass is upheld. This means that the same number of atoms for each element must be present on both sides of the equation. For instance, when looking at the reaction where a compound containing element X reacts with water to produce XO₂ and another product, we inspect each element's atoms.

To balance the equation, one must ensure that all atoms accounted for on the reactant side are adequately represented on the product side. In the provided exercise, hydrochloric acid (HCl) emerges as the other product when XCl₄ reacts with H₂O, adhering to the balanced reaction equation: XCl₄ + 2H₂O → XO₂ + 4HCl.

Compound Identification

When we talk about compound identification, we refer to the process of determining the composition and structure of a chemical substance. This is often done by analyzing its reactions and the properties of the products formed. In our exercise, by examining how XCl₄ reacts with water, and knowing that the resulting products are XO₂ and hydrochloric acid (HCl), we identify the reactants and products involved in the reaction, thus aiding in the identification of the unknown element X.

Compound identification also benefits from using reference materials such as the CRC Handbook of Chemistry and Physics. By comparing known properties of substances, such as melting and boiling points, one can make educated guesses about the identity of unknown elements or compounds.

Element Characteristics

Characteristics of elements like melting and boiling points aid in categorizing them as metals, nonmetals, or metalloids. Metals often have high melting points and are good conductors of heat and electricity. Nonmetals, on the other hand, have lower melting points and may exist across various states (solid, liquid, gas) at room temperature.

Element X's characteristics suggest it forms compounds with both ionic and covalent bonds, such as XO₂ and XCl₄, respectively. This dual behavior hints at X's identity as a metalloid. Metalloids have properties that are intermediate between metals and nonmetals, often making it challenging to classify them based solely on their behavior in chemical reactions.

Metal and Nonmetal Properties

Understanding the properties of metals and nonmetals helps us predict their reactions and the types of compounds they form. Metals tend to lose electrons and form positive ions, resulting in the creation of ionic compounds. Nonmetals usually gain electrons and form negative ions, leading to covalent compounds featuring shared pairs of electrons.

In the case of element X, we infer that it may be a metalloid due to its ability to form compounds typically associated with both metals (XO₂) and nonmetals (XCl₄). When attempting to determine if an element is a metal, nonmetal, or metalloid, looking at the types of bonds it forms and the physical states of its compounds can provide valuable clues.

Acid-Base Reaction

An acid-base reaction is a type of chemical reaction that involves the transfer of protons from an acid to a base. An example from our exercise is the reaction of water (H₂O) with XCl₄, which is a typical acid-base reaction. In this reaction, water acts as a base and accepts protons, leading to the formation of HCl, a known acid. This type of analysis is pivotal in predicting the products of a chemical reaction.

The concept of acid-base reactions is further exemplified when XCl₄ combines with water to produce HCl and XO₂. This gives students a practical understanding of how acids and bases interact to create new substances in chemistry, reinforcing the importance of being able to anticipate reaction products based on the types of compounds involved.