Free Printable Acids and Bases Worksheets - Free Printable

Let's solve each part of this Brønsted-Lowry Acids and Bases worksheet step by step.

---

1. Identify the hydrogen ion donor(s) (acids) and acceptor(s) (bases)

In Brønsted-Lowry theory:
- Acid: donates a proton (H⁺)
- Base: accepts a proton (H⁺)

#### a)
HNO₃(aq) + H₂O(l) → H₃O⁺(aq) + NO₃⁻(aq)
- HNO₃ donates H⁺ → H⁺ donor (acid)
- H₂O accepts H⁺ to become H₃O⁺ → H⁺ acceptor (base)

✔ H⁺ donors (acids): HNO₃
✔ H⁺ acceptors (bases): H₂O

---

#### b)
C₂H₅NH₂(aq) + H₂O(l) → C₂H₅NH₃⁺(aq) + OH⁻(aq)
- C₂H₅NH₂ accepts H⁺ to become C₂H₅NH₃⁺ → H⁺ acceptor (base)
- H₂O donates H⁺ to become OH⁻ → H⁺ donor (acid)

✔ H⁺ donors (acids): H₂O
✔ H⁺ acceptors (bases): C₂H₅NH₂

---

#### c)
CH₃COOH(aq) + H₂O(l) → CH₃COO⁻(aq) + H₃O⁺(aq)
- CH₃COOH donates H⁺ → H⁺ donor (acid)
- H₂O accepts H⁺ → H⁺ acceptor (base)

✔ H⁺ donors (acids): CH₃COOH
✔ H⁺ acceptors (bases): H₂O

---

2. Write the formulas for the conjugate base of each acid

The conjugate base is formed when an acid loses a proton (H⁺).

#### a) H₂SO₃
Lose one H⁺ → HSO₃⁻

#### b) HCO₃⁻
Lose one H⁺ → CO₃²⁻

#### c) NH₄⁺
Lose one H⁺ → NH₃

✔ Answers:
a) HSO₃⁻
b) CO₃²⁻
c) NH₃

---

3. Write the formulas for the conjugate acid of each base

The conjugate acid is formed when a base gains a proton (H⁺).

#### a) H₂O
Gain H⁺ → H₃O⁺

#### b) CO₃²⁻
Gain H⁺ → HCO₃⁻

#### c) PH₃
Gain H⁺ → PH₄⁺

✔ Answers:
a) H₃O⁺
b) HCO₃⁻
c) PH₄⁺

---

4. Identify whether each molecule/ion acts as an acid or base, and which theory applies

We’ll go through each species and classify it under Arrhenius, Brønsted-Lowry, and Lewis theories.

| Molecule/Ion | Acid or Base | Arrhenius | Brønsted-Lowry | Lewis |
|--------------|--------------|-----------|----------------|-------|
| Br⁻ | Base | | ✔ | ✔ |
| CN⁻ | Base | | ✔ | ✔ |
| H₂CO₃ | Acid | ✔ | ✔ | |
| NH₃ | Base | | ✔ | ✔ |
| HNO₂ | Acid | ✔ | ✔ | |
| Ba(OH)₂ | Base | ✔ | ✔ | |
| HCl | Acid | ✔ | ✔ | |
| AlCl₃ | Acid | | | ✔ |
| Cl⁻ | Base | | ✔ | ✔ |
| KOH | Base | ✔ | ✔ | |
| IO₃⁻ | Base | | ✔ | ✔ |
| CH₃COOH | Acid | ✔ | ✔ | |

---

🔍 Explanation of Each:

#### Br⁻
- Can accept H⁺ → forms HBr → Brønsted-Lowry base
- Has lone pair → can donate electrons → Lewis base
- Not Arrhenius (no OH⁻ or H⁺ in aqueous solution directly)

✔ Base, Brønsted-Lowry, Lewis

#### CN⁻
- Accepts H⁺ → HCN → Brønsted-Lowry base
- Lone pair → Lewis base

✔ Base, Brønsted-Lowry, Lewis

#### H₂CO₃
- Dissociates to H⁺ and HCO₃⁻ → Arrhenius acid
- Donates H⁺ → Brønsted-Lowry acid

✔ Acid, Arrhenius, Brønsted-Lowry

#### NH₃
- Accepts H⁺ → NH₄⁺ → Brønsted-Lowry base
- Lone pair on N → Lewis base
- Not Arrhenius (doesn't produce OH⁻ directly)

✔ Base, Brønsted-Lowry, Lewis

#### HNO₂
- Produces H⁺ in water → Arrhenius acid
- Donates H⁺ → Brønsted-Lowry acid

✔ Acid, Arrhenius, Brønsted-Lowry

#### Ba(OH)₂
- Produces OH⁻ in water → Arrhenius base
- Accepts H⁺ → Brønsted-Lowry base

✔ Base, Arrhenius, Brønsted-Lowry

#### HCl
- Produces H⁺ in water → Arrhenius acid
- Donates H⁺ → Brønsted-Lowry acid

✔ Acid, Arrhenius, Brønsted-Lowry

#### AlCl₃
- Not a proton donor → not Brønsted-Lowry
- Accepts electron pair (e.g., in AlCl₃ + Cl⁻ → AlCl₄⁻) → Lewis acid
- Not Arrhenius (no H⁺ or OH⁻)

✔ Acid, Lewis only

#### Cl⁻
- Accepts H⁺ → HCl → Brønsted-Lowry base
- Lone pairs → Lewis base

✔ Base, Brønsted-Lowry, Lewis

#### KOH
- Produces OH⁻ → Arrhenius base
- Accepts H⁺ → Brønsted-Lowry base

✔ Base, Arrhenius, Brønsted-Lowry

#### IO₃⁻
- Can accept H⁺ → HIO₃ → Brønsted-Lowry base
- Lone pairs → Lewis base

✔ Base, Brønsted-Lowry, Lewis

#### CH₃COOH
- Produces H⁺ → Arrhenius acid
- Donates H⁺ → Brønsted-Lowry acid

✔ Acid, Arrhenius, Brønsted-Lowry

---

✔ Final Answer Table:

| Molecule/Ion | Acid or Base | Arrhenius | Brønsted-Lowry | Lewis |
|--------------|--------------|-----------|----------------|-------|
| Br⁻ | Base | | ✔ | ✔ |
| CN⁻ | Base | | ✔ | ✔ |
| H₂CO₃ | Acid | ✔ | ✔ | |
| NH₃ | Base | | ✔ | ✔ |
| HNO₂ | Acid | ✔ | ✔ | |
| Ba(OH)₂ | Base | ✔ | ✔ | |
| HCl | Acid | ✔ | ✔ | |
| AlCl₃ | Acid | | | ✔ |
| Cl⁻ | Base | | ✔ | ✔ |
| KOH | Base | ✔ | ✔ | |
| IO₃⁻ | Base | | ✔ | ✔ |
| CH₃COOH | Acid | ✔ | ✔ | |

---

Summary Notes:

- Arrhenius: Only applies to H⁺ or OH⁻ in water.
- Brønsted-Lowry: Proton donor/acceptor (works in any solvent).
- Lewis: Electron pair acceptor/donor (most general).

Let me know if you'd like this as a printable PDF or need further explanations!