Chemistry worksheet focusing on pH, pOH, and ion concentration calculations.
![A chemistry worksheet titled "pH Worksheet" with exercises on calculating pH, pOH, [H⁺], and [OH⁻] for various solutions including HCl, NaOH, blood samples, and KOH.](/images2/ph-and-poh-worksheet/ph-and-poh-worksheet-7.png)
A chemistry worksheet titled "pH Worksheet" with exercises on calculating pH, pOH, [H⁺], and [OH⁻] for various solutions including HCl, NaOH, blood samples, and KOH.
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Step-by-step solution for: PH—pOH—[H+]—[OH-] Worksheet
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Show Answer Key & Explanations
Step-by-step solution for: PH—pOH—[H+]—[OH-] Worksheet
Let's solve each part of this pH/pOH worksheet step by step.
---
- pH = -log[H⁺]
- pOH = -log[OH⁻]
- [H⁺][OH⁻] = 1.0 × 10⁻¹⁴ (at 25°C)
- pH + pOH = 14
We'll use these formulas throughout.
---
## Problem 1: Calculate pH and pOH
| Solution | pH | pOH |
|--------|-----|-----|
| a. 0.020 M HCl | | |
| b. 0.0050 M NaOH | | |
| c. Blood sample: [H⁺] = 7.2 × 10⁻⁸ M | | |
| d. 0.00035 M KOH | | |
---
HCl is a strong acid → fully dissociates → [H⁺] = 0.020 M
- pH = -log(0.020) = -log(2.0 × 10⁻²) = 2 - log(2.0) ≈ 2 - 0.30 = 1.70
- pOH = 14 - pH = 14 - 1.70 = 12.30
✔ pH = 1.70, pOH = 12.30
---
NaOH is a strong base → fully dissociates → [OH⁻] = 0.0050 M
- pOH = -log(0.0050) = -log(5.0 × 10⁻³) = 3 - log(5.0) ≈ 3 - 0.70 = 2.30
- pH = 14 - pOH = 14 - 2.30 = 11.70
✔ pH = 11.70, pOH = 2.30
---
Given [H⁺], so:
- pH = -log(7.2 × 10⁻⁸) ≈ 8 - log(7.2) ≈ 8 - 0.857 = 7.143 ≈ 7.14
- pOH = 14 - 7.14 = 6.86
✔ pH = 7.14, pOH = 6.86
---
KOH is a strong base → [OH⁻] = 0.00035 M = 3.5 × 10⁻⁴ M
- pOH = -log(3.5 × 10⁻⁴) = 4 - log(3.5) ≈ 4 - 0.544 = 3.456 ≈ 3.46
- pH = 14 - 3.46 = 10.54
✔ pH = 10.54, pOH = 3.46
---
| Solution | pH | pOH |
|--------|----|-----|
| a. 0.020 M HCl | 1.70 | 12.30 |
| b. 0.0050 M NaOH | 11.70 | 2.30 |
| c. Blood sample | 7.14 | 6.86 |
| d. 0.00035 M KOH | 10.54 | 3.46 |
---
## Problem 2: Find [H⁺], [OH⁻], pOH from given pH
| pH | [H⁺] | [OH⁻] | pOH |
|-----|------|-------|-----|
| a. 2.90 | | | |
| b. 3.85 | | | |
| c. 10.81 | | | |
| d. 4.11 | | | |
| e. 11.61 | | | |
---
- [H⁺] = 10^(-pH) = 10^(-2.90) = 1.258 × 10⁻³ M ≈ 1.26 × 10⁻³ M
- pOH = 14 - 2.90 = 11.10
- [OH⁻] = 10^(-pOH) = 10^(-11.10) = 7.94 × 10⁻¹² M ≈ 7.9 × 10⁻¹² M
✔ [H⁺] = 1.26 × 10⁻³ M, [OH⁻] = 7.9 × 10⁻¹² M, pOH = 11.10
---
- [H⁺] = 10^(-3.85) ≈ 1.41 × 10⁻⁴ M
- pOH = 14 - 3.85 = 10.15
- [OH⁻] = 10^(-10.15) ≈ 7.08 × 10⁻¹¹ M ≈ 7.1 × 10⁻¹¹ M
✔ [H⁺] = 1.41 × 10⁻⁴ M, [OH⁻] = 7.1 × 10⁻¹¹ M, pOH = 10.15
---
- [H⁺] = 10^(-10.81) ≈ 1.55 × 10⁻¹¹ M
- pOH = 14 - 10.81 = 3.19
- [OH⁻] = 10^(-3.19) ≈ 6.46 × 10⁻⁴ M ≈ 6.5 × 10⁻⁴ M
✔ [H⁺] = 1.55 × 10⁻¹¹ M, [OH⁻] = 6.5 × 10⁻⁴ M, pOH = 3.19
---
- [H⁺] = 10^(-4.11) ≈ 7.76 × 10⁻⁵ M ≈ 7.8 × 10⁻⁵ M
- pOH = 14 - 4.11 = 9.89
- [OH⁻] = 10^(-9.89) ≈ 1.29 × 10⁻¹⁰ M ≈ 1.3 × 10⁻¹⁰ M
✔ [H⁺] = 7.8 × 10⁻⁵ M, [OH⁻] = 1.3 × 10⁻¹⁰ M, pOH = 9.89
---
- [H⁺] = 10^(-11.61) ≈ 2.45 × 10⁻¹² M ≈ 2.5 × 10⁻¹² M
- pOH = 14 - 11.61 = 2.39
- [OH⁻] = 10^(-2.39) ≈ 4.07 × 10⁻³ M ≈ 4.1 × 10⁻³ M
✔ [H⁺] = 2.5 × 10⁻¹² M, [OH⁻] = 4.1 × 10⁻³ M, pOH = 2.39
---
| pH | [H⁺] | [OH⁻] | pOH |
|----|------|-------|-----|
| a. 2.90 | 1.26 × 10⁻³ | 7.9 × 10⁻¹² | 11.10 |
| b. 3.85 | 1.41 × 10⁻⁴ | 7.1 × 10⁻¹¹ | 10.15 |
| c. 10.81 | 1.55 × 10⁻¹¹ | 6.5 × 10⁻⁴ | 3.19 |
| d. 4.11 | 7.8 × 10⁻⁵ | 1.3 × 10⁻¹⁰ | 9.89 |
| e. 11.61 | 2.5 × 10⁻¹² | 4.1 × 10⁻³ | 2.39 |
---
## Problem 3: Determine which solutions in #2 are acidic?
A solution is acidic if pH < 7
From #2:
- a. pH = 2.90 → ✔ Acidic
- b. pH = 3.85 → ✔ Acidic
- c. pH = 10.81 → ✘ Basic
- d. pH = 4.11 → ✔ Acidic
- e. pH = 11.61 → ✘ Basic
✔ Acidic solutions: a, b, d
---
## Problem 4: Rootbeer with [H⁺] = 1.9 × 10⁻⁵ M
- pH = -log(1.9 × 10⁻⁵) ≈ 5 - log(1.9) ≈ 5 - 0.278 = 4.722 ≈ 4.72
- pOH = 14 - 4.72 = 9.28
✔ pH = 4.72, pOH = 9.28
---
## Problem 5: Dr. Pepper has [H⁺] = 1.4 × 10⁻⁵ M
- pH = -log(1.4 × 10⁻⁵) ≈ 5 - log(1.4) ≈ 5 - 0.146 = 4.854 ≈ 4.85
✔ pH = 4.85
---
#### Problem 1:
| Solution | pH | pOH |
|--------|----|-----|
| a. 0.020 M HCl | 1.70 | 12.30 |
| b. 0.0050 M NaOH | 11.70 | 2.30 |
| c. Blood sample | 7.14 | 6.86 |
| d. 0.00035 M KOH | 10.54 | 3.46 |
#### Problem 2:
| pH | [H⁺] | [OH⁻] | pOH |
|----|------|-------|-----|
| a. 2.90 | 1.26 × 10⁻³ | 7.9 × 10⁻¹² | 11.10 |
| b. 3.85 | 1.41 × 10⁻⁴ | 7.1 × 10⁻¹¹ | 10.15 |
| c. 10.81 | 1.55 × 10⁻¹¹ | 6.5 × 10⁻⁴ | 3.19 |
| d. 4.11 | 7.8 × 10⁻⁵ | 1.3 × 10⁻¹⁰ | 9.89 |
| e. 11.61 | 2.5 × 10⁻¹² | 4.1 × 10⁻³ | 2.39 |
#### Problem 3:
Acidic solutions: a, b, d
#### Problem 4:
pH = 4.72, pOH = 9.28
#### Problem 5:
pH = 4.85
---
Let me know if you'd like this formatted as a printable PDF or need explanations for any steps!
---
Key Concepts:
- pH = -log[H⁺]
- pOH = -log[OH⁻]
- [H⁺][OH⁻] = 1.0 × 10⁻¹⁴ (at 25°C)
- pH + pOH = 14
We'll use these formulas throughout.
---
## Problem 1: Calculate pH and pOH
| Solution | pH | pOH |
|--------|-----|-----|
| a. 0.020 M HCl | | |
| b. 0.0050 M NaOH | | |
| c. Blood sample: [H⁺] = 7.2 × 10⁻⁸ M | | |
| d. 0.00035 M KOH | | |
---
a. 0.020 M HCl
HCl is a strong acid → fully dissociates → [H⁺] = 0.020 M
- pH = -log(0.020) = -log(2.0 × 10⁻²) = 2 - log(2.0) ≈ 2 - 0.30 = 1.70
- pOH = 14 - pH = 14 - 1.70 = 12.30
✔ pH = 1.70, pOH = 12.30
---
b. 0.0050 M NaOH
NaOH is a strong base → fully dissociates → [OH⁻] = 0.0050 M
- pOH = -log(0.0050) = -log(5.0 × 10⁻³) = 3 - log(5.0) ≈ 3 - 0.70 = 2.30
- pH = 14 - pOH = 14 - 2.30 = 11.70
✔ pH = 11.70, pOH = 2.30
---
c. Blood sample: [H⁺] = 7.2 × 10⁻⁸ M
Given [H⁺], so:
- pH = -log(7.2 × 10⁻⁸) ≈ 8 - log(7.2) ≈ 8 - 0.857 = 7.143 ≈ 7.14
- pOH = 14 - 7.14 = 6.86
✔ pH = 7.14, pOH = 6.86
---
d. 0.00035 M KOH
KOH is a strong base → [OH⁻] = 0.00035 M = 3.5 × 10⁻⁴ M
- pOH = -log(3.5 × 10⁻⁴) = 4 - log(3.5) ≈ 4 - 0.544 = 3.456 ≈ 3.46
- pH = 14 - 3.46 = 10.54
✔ pH = 10.54, pOH = 3.46
---
✔ Summary Table for Problem 1:
| Solution | pH | pOH |
|--------|----|-----|
| a. 0.020 M HCl | 1.70 | 12.30 |
| b. 0.0050 M NaOH | 11.70 | 2.30 |
| c. Blood sample | 7.14 | 6.86 |
| d. 0.00035 M KOH | 10.54 | 3.46 |
---
## Problem 2: Find [H⁺], [OH⁻], pOH from given pH
| pH | [H⁺] | [OH⁻] | pOH |
|-----|------|-------|-----|
| a. 2.90 | | | |
| b. 3.85 | | | |
| c. 10.81 | | | |
| d. 4.11 | | | |
| e. 11.61 | | | |
---
a. pH = 2.90
- [H⁺] = 10^(-pH) = 10^(-2.90) = 1.258 × 10⁻³ M ≈ 1.26 × 10⁻³ M
- pOH = 14 - 2.90 = 11.10
- [OH⁻] = 10^(-pOH) = 10^(-11.10) = 7.94 × 10⁻¹² M ≈ 7.9 × 10⁻¹² M
✔ [H⁺] = 1.26 × 10⁻³ M, [OH⁻] = 7.9 × 10⁻¹² M, pOH = 11.10
---
b. pH = 3.85
- [H⁺] = 10^(-3.85) ≈ 1.41 × 10⁻⁴ M
- pOH = 14 - 3.85 = 10.15
- [OH⁻] = 10^(-10.15) ≈ 7.08 × 10⁻¹¹ M ≈ 7.1 × 10⁻¹¹ M
✔ [H⁺] = 1.41 × 10⁻⁴ M, [OH⁻] = 7.1 × 10⁻¹¹ M, pOH = 10.15
---
c. pH = 10.81
- [H⁺] = 10^(-10.81) ≈ 1.55 × 10⁻¹¹ M
- pOH = 14 - 10.81 = 3.19
- [OH⁻] = 10^(-3.19) ≈ 6.46 × 10⁻⁴ M ≈ 6.5 × 10⁻⁴ M
✔ [H⁺] = 1.55 × 10⁻¹¹ M, [OH⁻] = 6.5 × 10⁻⁴ M, pOH = 3.19
---
d. pH = 4.11
- [H⁺] = 10^(-4.11) ≈ 7.76 × 10⁻⁵ M ≈ 7.8 × 10⁻⁵ M
- pOH = 14 - 4.11 = 9.89
- [OH⁻] = 10^(-9.89) ≈ 1.29 × 10⁻¹⁰ M ≈ 1.3 × 10⁻¹⁰ M
✔ [H⁺] = 7.8 × 10⁻⁵ M, [OH⁻] = 1.3 × 10⁻¹⁰ M, pOH = 9.89
---
e. pH = 11.61
- [H⁺] = 10^(-11.61) ≈ 2.45 × 10⁻¹² M ≈ 2.5 × 10⁻¹² M
- pOH = 14 - 11.61 = 2.39
- [OH⁻] = 10^(-2.39) ≈ 4.07 × 10⁻³ M ≈ 4.1 × 10⁻³ M
✔ [H⁺] = 2.5 × 10⁻¹² M, [OH⁻] = 4.1 × 10⁻³ M, pOH = 2.39
---
✔ Summary Table for Problem 2:
| pH | [H⁺] | [OH⁻] | pOH |
|----|------|-------|-----|
| a. 2.90 | 1.26 × 10⁻³ | 7.9 × 10⁻¹² | 11.10 |
| b. 3.85 | 1.41 × 10⁻⁴ | 7.1 × 10⁻¹¹ | 10.15 |
| c. 10.81 | 1.55 × 10⁻¹¹ | 6.5 × 10⁻⁴ | 3.19 |
| d. 4.11 | 7.8 × 10⁻⁵ | 1.3 × 10⁻¹⁰ | 9.89 |
| e. 11.61 | 2.5 × 10⁻¹² | 4.1 × 10⁻³ | 2.39 |
---
## Problem 3: Determine which solutions in #2 are acidic?
A solution is acidic if pH < 7
From #2:
- a. pH = 2.90 → ✔ Acidic
- b. pH = 3.85 → ✔ Acidic
- c. pH = 10.81 → ✘ Basic
- d. pH = 4.11 → ✔ Acidic
- e. pH = 11.61 → ✘ Basic
✔ Acidic solutions: a, b, d
---
## Problem 4: Rootbeer with [H⁺] = 1.9 × 10⁻⁵ M
- pH = -log(1.9 × 10⁻⁵) ≈ 5 - log(1.9) ≈ 5 - 0.278 = 4.722 ≈ 4.72
- pOH = 14 - 4.72 = 9.28
✔ pH = 4.72, pOH = 9.28
---
## Problem 5: Dr. Pepper has [H⁺] = 1.4 × 10⁻⁵ M
- pH = -log(1.4 × 10⁻⁵) ≈ 5 - log(1.4) ≈ 5 - 0.146 = 4.854 ≈ 4.85
✔ pH = 4.85
---
✔ Final Answers:
#### Problem 1:
| Solution | pH | pOH |
|--------|----|-----|
| a. 0.020 M HCl | 1.70 | 12.30 |
| b. 0.0050 M NaOH | 11.70 | 2.30 |
| c. Blood sample | 7.14 | 6.86 |
| d. 0.00035 M KOH | 10.54 | 3.46 |
#### Problem 2:
| pH | [H⁺] | [OH⁻] | pOH |
|----|------|-------|-----|
| a. 2.90 | 1.26 × 10⁻³ | 7.9 × 10⁻¹² | 11.10 |
| b. 3.85 | 1.41 × 10⁻⁴ | 7.1 × 10⁻¹¹ | 10.15 |
| c. 10.81 | 1.55 × 10⁻¹¹ | 6.5 × 10⁻⁴ | 3.19 |
| d. 4.11 | 7.8 × 10⁻⁵ | 1.3 × 10⁻¹⁰ | 9.89 |
| e. 11.61 | 2.5 × 10⁻¹² | 4.1 × 10⁻³ | 2.39 |
#### Problem 3:
Acidic solutions: a, b, d
#### Problem 4:
pH = 4.72, pOH = 9.28
#### Problem 5:
pH = 4.85
---
Let me know if you'd like this formatted as a printable PDF or need explanations for any steps!
Parent Tip: Review the logic above to help your child master the concept of ph and poh worksheet.
![Calculating pH, pOH, [H+] and [OH-] of Common Substances](/images2/ph-and-poh-worksheet/ph-and-poh-worksheet-27.png)