Problem 44 - Chemistry: An Atoms-Focused Approach

Question

Which is the formula of barium nitrate? (a) \(\mathrm{Ba}_{3} \mathrm{N}_{2}\) (b) \(\mathrm{Ba}_{2} \mathrm{NO}_{3} ;(\mathrm{c}) \mathrm{Ba}_{2}\left(\mathrm{NO}_{3}\right)_{2} ;(\mathrm{d}) \mathrm{Ba}\left(\mathrm{NO}_{3}\right)_{2}\)

Step-by-Step Solution

Answer

a) BaNO3 b) Ba2NO3 c) Ba(NO3)3 d) Ba(NO3)2 Answer: (d) Ba(NO3)2

Step 1: Identify the charges of the barium and nitrate ions

Barium is an alkaline earth metal in Group 2 of the periodic table, and it has a +2 charge. Nitrate is a polyatomic ion with a -1 charge.

Step 2: Combine the ions in a way that balances their charges

Since barium has a +2 charge and nitrate has a -1 charge, we need two nitrate ions for every barium ion to balance the charges and make the compound neutral.

Step 3: Write the formula for barium nitrate using parentheses

The formula for barium nitrate is Ba(NO\(_3\))\(_2\). This shows that there is one barium ion with a +2 charge combined with two nitrate ions, each with a -1 charge, resulting in a neutral compound.

Step 4: Identify the correct answer from the given options

The correct formula for barium nitrate, Ba(NO\(_3\))\(_2\), matches option (d). Therefore, the answer is (d) \(\mathrm{Ba}\left(\mathrm{NO}_{3}\right)_{2}\).

Key Concepts

Chemical Formula

A chemical formula is like a recipe for a compound. It tells us which atoms are present and how many in a single molecule or formula unit of a substance. When looking at barium nitrate, the formula tells us everything we need to know about the ions involved. The formula is written as \( \text{Ba(NO}_3\text{)}_2 \). This tells us that one barium ion combines with two nitrate ions. The symbols and subscripts indicate the types and ratios of atoms involved.

• "Ba" stands for barium.
• "NO_3" stands for the nitrate ion.
• The subscript "2" outside the parentheses shows there are two nitrate ions for each barium ion.

Understanding chemical formulas helps you predict the properties and behaviors of compounds.

Charge Balance

In chemistry, all compounds strive to be neutral, meaning they have no overall electrical charge. Charge balance is the concept that helps achieve this neutrality. In the case of barium nitrate, barium has a charge of +2 and nitrate has a charge of -1.
To make the compound neutral, these charges must balance out.

• Barium, with a +2 charge, needs two nitrate ions, each with a -1 charge, to balance the charge to zero.
• This ensures the compound has no excess positive or negative charge.

By balancing the charges of the ions, we create stable compounds like barium nitrate with the formula \( \text{Ba(NO}_3\text{)}_2 \). Charge balancing is crucial for understanding how different ions combine to form neutral compounds.

Polyatomic Ion

A polyatomic ion is a charged group of covalently bonded atoms. These can act as a single ion when forming compounds. Nitrate is an example of a polyatomic ion and has the formula \( \text{NO}_3^- \).
Polyatomic ions are important because they contain multiple atoms that function together as a unit.

• "Poly" means many, and "atomic" refers to atoms, indicating that these ions consist of several atoms.
• They can bond with other ions to form ionic compounds.

Recognizing polyatomic ions like nitrate helps you correctly write chemical formulas and understand how compounds are formed. They are common in many everyday chemical compounds.

Nitrate Ion

The nitrate ion is a specific type of polyatomic ion with the chemical formula \( \text{NO}_3^- \). It consists of one nitrogen atom and three oxygen atoms and carries an overall charge of -1.
This ion is frequently involved in forming compounds like barium nitrate.

• It is crucial in various chemical processes, including plant nutrition, since it is a key nutrient.
• Understanding how nitrate ions interact with other ions can help you predict the chemical behavior and properties of compounds that contain them.

The nitrate ion, with its stable configuration of nitrogen and oxygen atoms, is integral to both environmental and laboratory chemistry.