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

---

Answer Key for Question 1:

| Reaction | H⁺ Donors (Acids) | H⁺ Acceptors (Bases) |
|--------|-------------------|----------------------|
| a) | HNO₃ | H₂O |
| b) | H₂O | C₂H₅NH₂ |
| c) | CH₃COOH | 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 can act as an acid or base, and which theory applies

We’ll analyze each species under three theories:

- Arrhenius:
- Acid: produces H⁺ in water
- Base: produces OH⁻ in water

- Brønsted-Lowry:
- Acid: proton donor
- Base: proton acceptor

- Lewis:
- Acid: electron pair acceptor
- Base: electron pair donor

---

| 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 for Each Entry:

#### Br⁻
- Can accept H⁺ to form HBr → Brønsted-Lowry base
- Has lone pairs → Lewis base
- Not Arrhenius (no OH⁻ or H⁺ produced directly)

#### CN⁻
- Accepts H⁺ to form HCN → Brønsted-Lowry base
- Lone pairs → Lewis base
- Not Arrhenius

#### H₂CO₃
- Dissociates to H⁺ and HCO₃⁻ → Arrhenius acid
- Proton donor → Brønsted-Lowry acid
- Electron pair acceptor (in some cases) → Lewis acid (weakly), but primarily acid via proton donation

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

#### HNO₂
- Produces H⁺ in water → Arrhenius acid
- Proton donor → Brønsted-Lowry acid
- Can act as Lewis acid (electron pair acceptor, weakly)

#### Ba(OH)₂
- Produces OH⁻ in water → Arrhenius base
- Accepts H⁺ (can act as base) → Brønsted-Lowry base
- OH⁻ has lone pairs → Lewis base

#### HCl
- Produces H⁺ in water → Arrhenius acid
- Proton donor → Brønsted-Lowry acid
- Can accept electrons (e.g., in coordination complexes) → Lewis acid (weakly)

#### AlCl₃
- No H⁺/OH⁻ → not Arrhenius
- Doesn’t donate/accept H⁺ → not Brønsted-Lowry
- But strong Lewis acid – accepts electron pair (e.g., in AlCl₃ + Cl⁻ → AlCl₄⁻)

#### Cl⁻
- Accepts H⁺ to form HCl → Brønsted-Lowry base
- Lone pairs → Lewis base
- Not Arrhenius

#### KOH
- Produces OH⁻ → Arrhenius base
- Can accept H⁺ → Brønsted-Lowry base
- OH⁻ is Lewis base

#### IO₃⁻
- Can accept H⁺ → HIO₃ → Brønsted-Lowry base
- Lone pairs → Lewis base
- Not Arrhenius

#### CH₃COOH
- Produces H⁺ → Arrhenius acid
- Proton donor → Brønsted-Lowry acid
- Can accept electrons (in rare cases) → Lewis acid, but mainly acid via proton donation

---

✔ Final Answer Table (Completed):

| 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 of Answers:

#### 1. H⁺ Donors & Acceptors
- a) H⁺ donor: HNO₃; H⁺ acceptor: H₂O
- b) H⁺ donor: H₂O; H⁺ acceptor: C₂H₅NH₂
- c) H⁺ donor: CH₃COOH; H⁺ acceptor: H₂O

#### 2. Conjugate Bases
- a) H₂SO₃ → HSO₃⁻
- b) HCO₃⁻ → CO₃²⁻
- c) NH₄⁺ → NH₃

#### 3. Conjugate Acids
- a) H₂O → H₃O⁺
- b) CO₃²⁻ → HCO₃⁻
- c) PH₃ → PH₄⁺

#### 4. Classification Table – See completed table above.

Let me know if you'd like this formatted as a printable PDF or need explanations for any specific entry!