Question

The compound (NH_) \(_{2} \mathrm{SO}_{4}\) consists of two polyatomic ions. What are the names and electric charges of these ions? What is the molar mass of this compound?

Short answer

Ammonium (NH₄⁺) +1, Sulfate (SO₄²⁻) -2; Molar mass is 132.154 g/mol.

Step-by-step solution

Identify the Compound's Formula

The chemical formula given is \((\text{NH}_4)_2 \text{SO}_4\). This indicates that the compound consists of ammonium ions \((\text{NH}_4^+)\) and sulfate ions \((\text{SO}_4^{2-})\).

Determine the Name and Charge of Each Ion

The compound contains ammonium ions \((\text{NH}_4^+)\) and sulfate ions \((\text{SO}_4^{2-})\). The ammonium ion carries a +1 charge, and the sulfate ion carries a -2 charge.

Calculate the Molar Mass of Ammonium Sulfate

To find the molar mass of \((\text{NH}_4)_2 \text{SO}_4\), calculate the molar mass of each component. Ammonium \((\text{NH}_4^+)\) consists of 1 nitrogen (14.01 g/mol) and 4 hydrogen atoms (4 x 1.008 g/mol = 4.032 g/mol), totaling 18.042 g/mol per ammonium ion. Since there are two ammonium ions, the total molar mass for ammonium is 36.084 g/mol. The sulfate ion \((\text{SO}_4^{2-})\) consists of 1 sulfur (32.07 g/mol) and 4 oxygen atoms (4 x 16.00 g/mol = 64.00 g/mol), totaling 96.07 g/mol. The molar mass of ammonium sulfate is the sum of these: 36.084 g/mol (ammonium) + 96.07 g/mol (sulfate) = 132.154 g/mol.

Key concepts

Polyatomic Ions

When dealing with the compound ammonium sulfate \((\text{NH}_4)_2 \text{SO}_4\), it is essential to understand the concept of polyatomic ions. These are ions that consist of two or more atoms that are covalently bonded together, acting as a single charged entity. In ammonium sulfate, we have two different polyatomic ions:

• Ammonium ion \((\text{NH}_4^+)\): This ion is made up of one nitrogen atom and four hydrogen atoms, and it carries a positive charge of +1. This positive charge makes it attractive to negatively charged ions.
• Sulfate ion \((\text{SO}_4^{2-})\): This ion consists of one sulfur atom bonded to four oxygen atoms, and it carries a negative charge of -2. This allows it to pair with positively charged ions like ammonium.

Understanding these ions is important because they appear frequently in chemistry and have specific properties and charges that influence how compounds like ammonium sulfate are formed and used.

Molar Mass Calculation

Calculating the molar mass is crucial for understanding how much a compound weighs per mole and is key in stoichiometry. To find the molar mass of ammonium sulfate \((\text{NH}_4)_2 \text{SO}_4\), you need to add up the atomic masses of each element, as they appear in the compound.Let's break it down:

• First, determine the molar mass of the ammonium ion \((\text{NH}_4^+)\). This includes 1 nitrogen atom (14.01 g/mol) and 4 hydrogen atoms (4 x 1.008 g/mol). Add these together to get 18.042 g/mol for one ammonium ion. Since there are two ammonium ions, multiply by 2 to obtain 36.084 g/mol.
• Next, calculate the molar mass of the sulfate ion \((\text{SO}_4^{2-})\). This involves 1 sulfur atom (32.07 g/mol) and 4 oxygen atoms (4 x 16.00 g/mol). Adding these gives 96.07 g/mol for the sulfate ion.
• Finally, add the molar mass of the ammonium and sulfate ions: 36.084 g/mol + 96.07 g/mol = 132.154 g/mol. This total represents the molar mass of ammonium sulfate.

Understanding this calculation helps in determining how much of each element is present in a compound and is a foundational skill in chemical analysis.

Chemical Formula Interpretation

Chemical formulas convey significant information about the composition of compounds. The formula for ammonium sulfate \((\text{NH}_4)_2 \text{SO}_4\) reveals details about its structure.Here's how to interpret it:

• The parenthesis \((\text{NH}_4)_2\) tells us there are two ammonium ions in the compound. It indicates the repetition of \(\text{NH}_4^+\) twice, signifying its count within the molecule.
• \(\text{SO}_4\) represents one sulfate ion. This doesn't have a parenthesis which means it occurs once in the compound. The subscript numbers 2 in \((\text{NH}_4)_2\) and 4 in \(\text{SO}_4\) inform us about the number of atoms involved for each of the ions.

Decoding these symbols and numbers enables chemists to understand the ratio of ions and elements in compounds, which is necessary for predicting chemical behavior and reactions.

Ion Charges

In chemistry, understanding ion charges is key to mastering chemical reactions and bonding. Ions are charged particles, and their charges are pivotal in how compounds like ammonium sulfate form.In ammonium sulfate \((\text{NH}_4)_2 \text{SO}_4\), each type of ion has a specific charge which affects their interactions:

• The ammonium ion \((\text{NH}_4^+)\) carries a +1 charge. This positive charge means it is attracted to negatively charged ions.
• The sulfate ion \((\text{SO}_4^{2-})\) has a -2 charge, making it reactive with positively charged ions.

In the compound, two ammonium ions combine to balance the charge of one sulfate ion. The equal but opposite charges (+2 from two ammonium ions and -2 from one sulfate ion) result in a neutral compound. Understanding these charges helps explain why certain chemicals bond together and how they interact in different environments.