Problem 41 - Chemistry The Molecular Science

Question

Write the chemical formula for calcium nitrate, barium chloride, and ammonium phosphate. What are the names and charges of all the ions in these three compounds?

Step-by-Step Solution

Answer

Calcium nitrate: Ca(NO\(_3\))\(_2\), Barium chloride: BaCl\(_2\), Ammonium phosphate: (NH\(_4\))\(_3\)PO\(_4\).

Step 1: Understanding the ions in calcium nitrate

Calcium nitrate is composed of calcium ions and nitrate ions. Calcium (Ca) typically forms a +2 charge, so it is written as Ca\(^{2+}\). Nitrate is a polyatomic ion with the formula NO\(_3^-\) and a -1 charge.

Step 2: Write the formula for calcium nitrate

To create a balanced chemical formula, the total positive and negative charges must equal zero. Since calcium has a +2 charge and nitrate has a -1 charge, two nitrate ions are needed: Ca(NO\(_3\))\(_2\).

Step 3: Understanding the ions in barium chloride

Barium chloride is made of barium ions and chloride ions. Barium (Ba) forms a +2 charge, written as Ba\(^{2+}\). Chloride (Cl) is a simple ion with a -1 charge.

Step 4: Write the formula for barium chloride

A balanced chemical formula needs equal total charges. Since barium is +2 and chloride is -1, two chloride ions are required: BaCl\(_2\).

Step 5: Understanding the ions in ammonium phosphate

Ammonium phosphate is composed of ammonium ions and phosphate ions. The ammonium ion (NH\(_4^+\)) carries a +1 charge, and phosphate (PO\(_4^{3-}\)) carries a -3 charge.

Step 6: Write the formula for ammonium phosphate

To balance the charges, three ammonium ions are needed to counter the -3 charge of one phosphate ion: (NH\(_4\))\(_3\)PO\(_4\).

Step 7: Summarize ion names and charges

Calcium nitrate contains calcium ions (Ca\(^{2+}\)) and nitrate ions (NO\(_3^-\)). Barium chloride contains barium ions (Ba\(^{2+}\)) and chloride ions (Cl\(^-\)). Ammonium phosphate contains ammonium ions (NH\(_4^+\)) and phosphate ions (PO\(_4^{3-}\)).

Key Concepts

Ions and Charges

In chemistry, understanding ions and their charges is fundamental when forming chemical compounds. Ions are atoms or molecules that have gained or lost one or more electrons, resulting in a positive or negative charge. This charge is critical because it determines how ions interact with one another, often forming stable compounds through ionic bonding.

Here are the key points to remember about ions:

• Positive ions, or cations, form when an atom loses electrons, gaining a positive charge.
• Negative ions, also known as anions, form when an atom gains electrons, acquiring a negative charge.

The ability to combine ions to create neutral compounds relies on balancing their total charges. For example, a compound with a +2 charge ion would need ions adding up to -2 to balance out to zero, making the compound neutral overall.

Calcium Nitrate

Calcium nitrate is a white crystalline compound often used in fertilizers. It consists of both calcium ions and nitrate ions, requiring knowledge of their respective charges to form its chemical formula.

• Calcium Ion (Ca²⁺): Calcium commonly forms a divalent cation, meaning it has a +2 charge because it loses two electrons.
• Nitrate Ion (NO₃^-): This is a polyatomic ion with a -1 charge, consisting of one nitrogen atom bonded to three oxygen atoms.

Writing the Formula

To write the formula for calcium nitrate, you need to balance the positive charge of calcium with the negative charges of nitrate. This requires two nitrate ions for every calcium ion, leading to the formula: \[ \text{Ca(NO}_3\text{)}_2 \]

Barium Chloride

Barium chloride is another compound created through the interaction of ions, specifically barium and chloride ions. It is often used in laboratory metal analysis.

• Barium Ion (Ba²⁺): Similar to calcium, barium forms a +2 cation by losing two electrons.
• Chloride Ion (Cl^-): Simple halide ion with a -1 charge, formed by gaining an electron.

Balancing Charges for the Formula

To strike charge balance, one barium ion (+2) needs two chloride ions (-1 each), leading to the composition:\[ \text{BaCl}_2 \] This formula confirms neutral charge as the total positive and negative charges equate to zero.

Ammonium Phosphate

Ammonium phosphate is a compound widely used in fertilizers. It provides essential nutrients to plants, supplying them with nitrogen and phosphorus. Its formulation involves ammonium and phosphate ions.

• Ammonium Ion (NH₄⁺): An unusual ion that carries a +1 charge, composed of nitrogen and hydrogen atoms.
• Phosphate Ion (PO₄^3-): This polyatomic ion has a -3 charge, containing one phosphorus atom surrounded by four oxygen atoms.

Creating the Chemical Formula

The chemical formula for ammonium phosphate balances the three ammonium ions needed to balance the charge of one phosphate ion:\[ \text{(NH}_4\text{)}_3\text{PO}_4 \]This arrangement gives the compound a neutral charge by compensating the charges perfectly.