In an acidic solution, how does the concentration of H 3 O + compare to the concentration of OH - ?

Hey, everyone, we're asked to compare the concentrations of hydro num ion with a formula of H plus and hydroxide ion with a formula of O H minus in an acidic solution. So we know that for an acidic solution, our ph must be less than seven. And let's go ahead and take a look at how an acid reacts. So we know that an acid is a substance that donates a proton. For example, we can go ahead and take any acid which I'll label as H X and we can react this with water. Now, when we react this with water, we form our hydro num ion and our anion, as we can see right here, an acid creates more of our hydro num ion. So to answer this question, our concentration of hydro num ion must be greater than the concentration of hydroxide ion due to this reason. Now, I hope this made sense and let us know if you have any questions.

Table of contents

Skip topic navigation

1. Matter and Measurements4h 31m
2. Atoms and the Periodic Table5h 23m
3. Ionic Compounds2h 18m
4. Molecular Compounds2h 18m
5. Classification & Balancing of Chemical Reactions3h 17m
6. Chemical Reactions & Quantities2h 27m
7. Energy, Rate and Equilibrium3h 46m
8. Gases, Liquids and Solids3h 25m
9. Solutions4h 10m
10. Acids and Bases3h 29m
11. Nuclear Chemistry56m
BONUS: Lab Techniques and Procedures1h 38m
BONUS: Mathematical Operations and Functions47m
12. Introduction to Organic Chemistry1h 34m
13. Alkenes, Alkynes, and Aromatic Compounds2h 12m
14. Compounds with Oxygen or Sulfur1h 6m
15. Aldehydes and Ketones1h 1m
16. Carboxylic Acids and Their Derivatives1h 11m
17. Amines39m
18. Amino Acids and Proteins1h 51m
19. Enzymes1h 37m
20. Carbohydrates1h 41m
21. The Generation of Biochemical Energy2h 8m
22. Carbohydrate Metabolism2h 22m
23. Lipids2h 26m
24. Lipid Metabolism1h 45m
25. Protein and Amino Acid Metabolism1h 37m
26. Nucleic Acids and Protein Synthesis2h 54m

10. Acids and Bases

The pH Scale

GOB Chemistry

10. Acids and Bases

The pH Scale

Previous problemNext problem

1:08 minutes

Problem 27

Textbook Question

In an acidic solution, how does the concentration of H₃O⁺ compare to the concentration of OH^-?

Verified step by step guidance

Understand that in any aqueous solution, the concentrations of H₃O⁺ (hydronium ions) and OH⁻ (hydroxide ions) are related by the ion-product constant for water, Kw, which is 1.0 × 10⁻¹⁴ at 25°C. This relationship is expressed as:

K_{w} = [H_{3} O

⁺] × [OH⁻].

Recognize that an acidic solution is defined as one where the concentration of H₃O⁺ is greater than the concentration of OH⁻. This means:

[H_{3} O

⁺] > [OH⁻].

Recall that the pH of a solution is a measure of its acidity and is calculated using the formula:

pH = − \log [H_{3} O

⁺]. For an acidic solution, the pH is less than 7.

Use the relationship between pH and pOH, which is given by:

pH + pOH = 14

. In an acidic solution, since the pH is less than 7, the pOH will be greater than 7, indicating a lower concentration of OH⁻.

Conclude that in an acidic solution, the concentration of H₃O⁺ is higher than the concentration of OH⁻, and this imbalance is what defines the solution as acidic.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Video duration:

Play a video:

Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Acidic Solutions

An acidic solution is characterized by a higher concentration of hydronium ions (H₃O⁺) compared to hydroxide ions (OH⁻). This imbalance results in a pH value less than 7, indicating acidity. In such solutions, the presence of H₃O⁺ ions is what defines the solution as acidic, affecting various chemical reactions and properties.

pH Scale

The pH scale quantifies the acidity or basicity of a solution, ranging from 0 to 14. A pH less than 7 indicates an acidic solution, where the concentration of H₃O⁺ is greater than that of OH⁻. Each unit change in pH represents a tenfold change in H₃O⁺ concentration, making it a crucial tool for understanding the nature of solutions.

Ion Product of Water

The ion product of water (Kw) is the equilibrium constant for the self-ionization of water, defined as Kw = [H₃O⁺][OH⁻] = 1.0 x 10⁻¹⁴ at 25°C. In acidic solutions, as the concentration of H₃O⁺ increases, the concentration of OH⁻ must decrease to maintain this constant. This relationship is fundamental in determining the balance of ions in any aqueous solution.

Watch next

Master The pH Scale Concept 1 with a bite sized video explanation from Jules

Start learning