Question

Platinum is a transition element and forms \(\mathrm{Pt}^{2+}\) and \(\mathrm{Pt}^{4+}\) ions. Write the formulas for the compounds of each of these ions with (a) chloride ions and (b) sulfide ions.

Short answer

\(\mathrm{PtCl}_2\), \(\mathrm{PtCl}_4\), \(\mathrm{PtS}\), \(\mathrm{PtS}_2\)

Step-by-step solution

Identify the Ions

To determine the chemical formulas of the compounds, we first need to identify the ions involved. Platinum can form two different cations: \(\mathrm{Pt}^{2+}\) and \(\mathrm{Pt}^{4+}\). Chloride ions are \(\mathrm{Cl}^-\) and sulfide ions are \(\mathrm{S}^{2-}\).

Combine \(\mathrm{Pt}^{2+}\) with Chloride Ions

Since \(\mathrm{Pt}^{2+}\) has a charge of \(+2\) and chloride ions \(\mathrm{Cl}^-\) have a charge of \(-1\), we need two chloride ions to balance the charge of one \(\mathrm{Pt}^{2+}\) ion. Thus, the formula is \(\mathrm{PtCl}_2\).

Combine \(\mathrm{Pt}^{4+}\) with Chloride Ions

\(\mathrm{Pt}^{4+}\) has a charge of \(+4\). To get a neutral compound, we need four chloride ions \(\mathrm{Cl}^-\). Therefore, the formula is \(\mathrm{PtCl}_4\).

Combine \(\mathrm{Pt}^{2+}\) with Sulfide Ions

The \(\mathrm{Pt}^{2+}\) ion has a charge of \(+2\), and sulfide ions \(\mathrm{S}^{2-}\) have a charge of \(-2\). No additional ions are needed to balance this charge, so the formula is \(\mathrm{PtS}\).

Combine \(\mathrm{Pt}^{4+}\) with Sulfide Ions

For the \(\mathrm{Pt}^{4+}\) ion, which has a charge of \(+4\), we need two sulfide ions \(\mathrm{S}^{2-}\) to balance the charge. Thus, the formula for this compound is \(\mathrm{PtS}_2\).

Key concepts

Transition Elements

Transition elements are fascinating members of the periodic table. They are located in the central block, consisting of metals known for their ability to form various oxidation states. This versatility arises from the presence of loosely bound d electrons. Such flexibility allows transition elements to participate in a wide range of chemical reactions.
A common characteristic of transition elements is their ability to form colored compounds. This is due to electron transitions between d-orbitals, which absorb specific wavelengths of light. Moreover, many transition elements, like platinum, are known for their catalytic properties. This makes them incredibly valuable in industrial and chemical processes. Understanding the intricate nature of transition elements helps us appreciate their role in both biological systems and technological advancements.

Ion Charges

Ion charges are crucial in determining the chemical behavior of elements. An ion is an atom or molecule that has gained or lost one or more electrons, resulting in a net positive or negative charge. Cations are positively charged ions, formed when an atom loses electrons, while anions are negatively charged, created by gaining electrons.
For instance, in platinum's case, it forms two main cations: \(\mathrm{Pt}^{2+}\) and \(\mathrm{Pt}^{4+}\). These different charges mean that platinum can form compounds with varying properties. The charge of an ion influences how it can combine with other ions to form stable compounds. It's essential to balance the charges when forming compounds, ensuring that the sum of positive and negative charges equals zero. Understanding ion charges allows us to predict how elements will interact in chemical reactions.

Compounds of Platinum

Platinum is a remarkable element, not only for its rarity but also for its ability to form a variety of compounds. As a transition metal, it can exist in several oxidation states, notably \(\mathrm{Pt}^{2+}\) and \(\mathrm{Pt}^{4+}\). This enables platinum to form multiple compounds with the same or different elements.
When combining with chloride ions (\(\mathrm{Cl}^-\)), the formulas for the resulting compounds depend on platinum's ionic charge:

• For \(\mathrm{Pt}^{2+}\), the compound is \(\mathrm{PtCl}_2\).
• With \(\mathrm{Pt}^{4+}\), the compound becomes \(\mathrm{PtCl}_4\).

In the case of combining with sulfide ions (\(\mathrm{S}^{2-}\)):

• With the \(\mathrm{Pt}^{2+}\) ion, the compound formed is \(\mathrm{PtS}\).
• For \(\mathrm{Pt}^{4+}\), the resulting compound is \(\mathrm{PtS}_2\).

These varying formulas highlight the importance of platinum's charge in determining the specific compounds it can form.

Balancing Chemical Equations

Balancing chemical equations is a fundamental skill in chemistry. It involves ensuring that the number of atoms for each element is the same on both sides of the equation. This reflects the law of conservation of mass, which states that matter is neither created nor destroyed in a chemical reaction.
To balance an equation, you'll need to adjust the coefficients (the numbers in front of compounds) so that both sides have equal numbers of each type of atom. It's a bit like solving a puzzle; you adjust, check, and readjust until balance is achieved.
Balancing equations can be particularly challenging with transition elements, as they might form multiple ions. For example, when dealing with platinum compounds, understanding its ionic states (\(\mathrm{Pt}^{2+}\) and \(\mathrm{Pt}^{4+}\)) is key. Correctly balancing these reactions ensures the accurate depiction of how substances interact in a chemical process. With practice, balancing equations becomes an intuitive and essential part of studying chemistry.