Acid and Base Worksheet 1-07-08 Ans Key | PDF | Acid | Chemical ... - Free Printable

It looks like you've uploaded a completed Acid and Base Worksheet - Answers. The document already contains the correct answers and explanations for each question. However, I'll go through each problem step by step to explain the solutions clearly, so you can understand the reasoning behind them.

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1) Using the Brønsted-Lowry theory of acids and bases

The Brønsted-Lowry theory defines:
- An acid as a proton (H⁺) donor.
- A base as a proton (H⁺) acceptor.
- Each acid has a conjugate base (formed after losing H⁺).
- Each base has a conjugate acid (formed after gaining H⁺).

Let’s analyze each reaction:

#### a)
Reaction:
$$ \text{HNO}_3 + \text{OH}^- \rightarrow \text{H}_2\text{O} + \text{NO}_3^- $$

- HNO₃ donates a proton → acid
- OH⁻ accepts a proton → base
- NO₃⁻ is the conjugate base of HNO₃
- H₂O is the conjugate acid of OH⁻

✔ Conjugate pairs:
- HNO₃ / NO₃⁻
- H₂O / OH⁻

> ✔ Correct answer in red: "HNO₃ and NO₃⁻ make one pair; H₂O and OH⁻ make the other"

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#### b)
Reaction:
$$ \text{CH}_3\text{NH}_2 + \text{H}_2\text{O} \rightarrow \text{CH}_3\text{NH}_3^+ + \text{OH}^- $$

- CH₃NH₂ accepts a proton → base
- H₂O donates a proton → acid
- CH₃NH₃⁺ is the conjugate acid of CH₃NH₂
- OH⁻ is the conjugate base of H₂O

✔ Conjugate pairs:
- CH₃NH₂ / CH₃NH₃⁺
- H₂O / OH⁻

> ✔ Correct answer in red: "CH₃NH₂ and CH₃NH₃⁺ make one pair; OH⁻ and H₂O make the other"

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#### c)
Reaction:
$$ \text{OH}^- + \text{HPO}_4^{2-} \rightarrow \text{H}_2\text{O} + \text{PO}_4^{3-} $$

- OH⁻ donates a proton? Wait — OH⁻ can act as an acid or base depending on context.

Here, OH⁻ accepts a proton from HPO₄²⁻ → base
- HPO₄²⁻ donates a proton → acid
- H₂O is the conjugate acid of OH⁻
- PO₄³⁻ is the conjugate base of HPO₄²⁻

✔ Conjugate pairs:
- OH⁻ / H₂O
- HPO₄²⁻ / PO₄³⁻

> ✔ Correct answer in red: "HPO₄²⁻ and PO₄³⁻ make one pair; OH⁻ and H₂O make the other"

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2) NaOH as a base under three theories

Let’s describe NaOH using all three acid-base theories:

#### Arrhenius Base:
- Produces OH⁻ ions in water.
- NaOH → Na⁺ + OH⁻ → increases OH⁻ concentration.
✔ So, NaOH is an Arrhenius base because it creates OH⁻ in water.

#### Brønsted-Lowry Base:
- Accepts a proton (H⁺).
- OH⁻ can accept H⁺ to form H₂O.
- Example: OH⁻ + H⁺ → H₂O
✔ So, NaOH is a Brønsted-Lowry base because OH⁻ accepts H⁺.

#### Lewis Base:
- Donates a lone pair of electrons.
- The oxygen in OH⁻ has lone pairs that can be donated.
- In reactions like OH⁻ + H⁺ → H₂O, OH⁻ donates electrons to H⁺.
✔ So, NaOH is a Lewis base because the hydroxide ion donates electrons.

✔️ All explanations in the answer are correct.

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3) Reaction between HCl and NH₃

Equation:
$$ \text{HCl} + \text{NH}_3 \rightarrow \text{NH}_4\text{Cl} $$

This is a proton transfer:
- HCl donates H⁺ → acid
- NH₃ accepts H⁺ → base

But now we’re asked about Lewis acid/base:

#### Lewis Acid:
- Electron pair acceptor
- H⁺ (from HCl) accepts a lone pair from NH₃
- So, HCl is the Lewis acid (H⁺ is the electron acceptor)

#### Lewis Base:
- Electron pair donor
- NH₃ has a lone pair on nitrogen → donates it to H⁺
- So, NH₃ is the Lewis base

✔ Answer is correct:
- NH₃ is a Lewis base (donates lone pair)
- HCl is a Lewis acid (accepts electrons)

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4) Reactions of oxides with water

We classify oxides as acidic anhydrides (form acids) or basic anhydrides (form bases).

#### a) Carbon dioxide and water
$$ \text{CO}_2 + \text{H}_2\text{O} \rightarrow \text{H}_2\text{CO}_3 $$
- CO₂ forms carbonic acid → acidic
- So, CO₂ is an acidic anhydride

✔ Correct

#### b) Sodium oxide and water
$$ \text{Na}_2\text{O} + \text{H}_2\text{O} \rightarrow 2\text{NaOH} $$
- Forms a base (NaOH)
- So, Na₂O is a basic anhydride

✔ Correct

#### c) Dichlorine trioxide and water
$$ \text{Cl}_2\text{O}_3 + \text{H}_2\text{O} \rightarrow 2\text{HClO}_2 $$
- Forms chlorous acid → acidic
- So, Cl₂O₃ is an acidic anhydride

✔ Correct

#### d) Beryllium oxide and water
$$ \text{BeO} + \text{H}_2\text{O} \rightarrow \text{Be(OH)}_2 $$
- Forms Be(OH)₂, which is a weak base
- So, BeO is a basic anhydride

✔ Correct

Note: Although BeO is amphoteric in some contexts, in this case, it's reacting to form a hydroxide, so it's classified as a basic anhydride here.

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✔ Final Summary: All answers in the worksheet are correct and well-explained!

If you were asking for help understanding or verifying these answers, then yes — everything is accurate and properly explained.

Let me know if you'd like:
- A version without red text (cleaned up),
- Practice problems,
- Or a deeper dive into any concept (e.g., Lewis vs. Brønsted).