SOLUTION: POGIL Naming Acids - Studypool - Free Printable

You've uploaded a chemistry worksheet titled "Naming Acids", focusing on binary acids. The document includes a model table, questions, and some answers already filled in (in blue). Let's go through the problem, verify the solutions, and explain each part thoroughly.

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🔍 Overview of the Task

The goal is to understand how binary acids are named and what makes them unique. Binary acids consist of hydrogen and one other nonmetal element. When dissolved in water, they produce H₃O⁺ (hydronium) ions, making the solution acidic.

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## ✔ Step-by-Step Solution & Explanation

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Model 1 – Binary Acids Table

| Acid | Name of acid in aqueous solution | Cation (+)* | Anion (–) |
|------|-------------------------------|-------------|-----------|
| HCl | Hydrochloric acid | H₃O⁺ | Cl⁻ |
| HBr | Hydrobromic acid | H₃O⁺ | Br⁻ |
| H₂S | Hydrosulfuric acid | 2H₃O⁺ | S²⁻ |
| HF | Hydrofluoric acid | H₃O⁺ | F⁻ |

> ✔ Note: All entries in this table are correct as shown.
>
> - The cation is always H₃O⁺ (hydronium ion), formed when H⁺ combines with H₂O.
> - The anion comes from the negative ion of the nonmetal:
> - Cl⁻ → chloride
> - Br⁻ → bromide
> - S²⁻ → sulfide
> - F⁻ → fluoride

> 💡 Important: In aqueous solution, H⁺ does not exist freely; it binds to water to form H₃O⁺.

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Question 1: Complete the cation and anion columns

✔ Already completed correctly in the table:
- Cation: Always H₃O⁺ per hydrogen ion released.
- For H₂S, two H⁺ ions are released → 2H₃O⁺
- Anions: Match the charge of the nonmetal:
- Cl⁻, Br⁻, F⁻ → -1 charge
- S²⁻ → -2 charge

✔️ So the table is complete and correct.

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Question 2: Why does hydrosulfuric acid contain two hydrogens?

> Answer given:
> *Hydrosulfuric acid contains two hydrogens because sulfur has a charge of -2.*

✔ Correct!
- Sulfur (S) typically forms a -2 anion (S²⁻).
- To balance the charge, you need two H⁺ ions → H₂S.
- So, H₂S dissociates into 2H⁺ + S²⁻, which becomes 2H₃O⁺ + S²⁻ in water.

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Question 3: Naming Patterns

#### a. What prefix is used at the beginning of the name for all binary acids?

> Answer given: *Hydro-*
✔ Correct!
All binary acids start with the prefix "hydro-", e.g., hydrochloric, hydrobromic, hydrosulfuric.

#### b. What suffix is used at the end of the name for all binary acids?

> Answer given: *-ic*
✔ Correct!
Binary acids end with "-ic", e.g., hydrochloric acid.

> ⚠️ Note: This contrasts with oxyacids (which contain oxygen), where names often end in -ous or -ic depending on the number of oxygen atoms.

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Question 4: Why are these called "binary" acids?

> Answer given:
> *The reason why these acids are referred to as "binary" is that they contain two types of elements.*

✔ Correct!
- "Binary" means two elements.
- These acids are composed of hydrogen and one other nonmetal (e.g., Cl, Br, S, F).
- So, only two elements are present → hence, binary acids.

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Question 5: Write a rule for naming binary acids.

> Answer given:
> *Binary acids must contain Hydrogen and one other element*

✔ Mostly correct, but can be more precise.

🔧 Improved Rule:

> Rule for naming binary acids:
> 1. The acid must contain hydrogen (H) and one other nonmetal element.
> 2. The name starts with the prefix "hydro-".
> 3. The name of the second element is modified by replacing its ending with "-ic".
> 4. The word "acid" is added at the end.

✔ Example:

- HCl → Hydro + chlor + ic → Hydrochloric acid
- H₂S → Hydro + sulf + uric → Hydrosulfuric acid *(note: "sulfur" becomes "sulfuric")*

> 📌 Note: The root name comes from the anion name, but we drop the "-ide" and add "-ic".

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## ✔ Final Summary of Answers

| Question | Answer |
|--------|--------|
| 1 | Cations: H₃O⁺ (or 2H₃O⁺ for H₂S); Anions: Cl⁻, Br⁻, S²⁻, F⁻ — all correct. |
| 2 | Because sulfur has a -2 charge, requiring two H⁺ ions to balance. |
| 3a | Prefix: hydro- |
| 3b | Suffix: -ic |
| 4 | They contain two elements (hydrogen and one nonmetal) → "binary". |
| 5 | Binary acids are named using "hydro-" + root of anion + "-ic" + "acid". |

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## 🎯 Key Takeaways

- Binary acids: H + one nonmetal (no oxygen)
- Naming pattern: Hydro___ic acid
- In water: Produce H₃O⁺ ions → define acidity
- Anion charge determines number of H atoms: e.g., S²⁻ → H₂S

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Let me know if you'd like help with oxyacids (like HNO₃, H₂SO₄) next!