Dilute Acids - Acids, Dilute acids, Practice Problems and FAQs

Most likely, you now have a bottle of vinegar in your cabinet. You might, however, be one of the many who solely use vinegar as a salad dressing or a sauce for many dishes.

However, vinegar has uses beyond cooking. Because acetic acid is used in its production, it also works well as a cleanser and disinfectant.

Could you please clarify whether vinegar is a weak acid or a diluted acid?

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You must all be thinking at this moment Are weak acid and dilute acid, not the same thing?

What standards should be used if they are different?

Let's examine the idea and learn how weak acids and diluted acid can be distinguished from one another!

TABLE OF CONTENT

Acids
Dilute Acids
Difference between Concentrated Acids and Diluted Acids
Practice Problems
Frequently Asked Questions

Acids:

An organic or inorganic compound that releases hydrogen ions (H+) when dissolved in water is referred to as an acid.

Example:

HClH⁺+Cl^-

H₂SO₄²H⁺+SO₄^2-

HNO₃H⁺+NO₃^-

There are basically two types of acids

Strong acids are those that readily emit a lot of hydrogen ions into the water. Strong acids include inorganic acids like Sulfuric acid H₂SO₄, Nitric acid HNO₃, and Hydrochloric acid HCl. Strong acids are also known as Mineral acids.

Weak acids are those that only release a few hydrogen ions in water. Acetic acid CH₃COOH, oxalic acid H₂C₂O₄, and Hydrogen cyanide HCN are a few examples of weak organic acids. Generally, weak acids are also known as Organic acids.

Dilute Acids:

When concentrated acids have been diluted with a significant amount of water they are referred to as dilute acids.

It doesn't make acid less reactive or less strong. It only decreases the amount of acid in the solution. Hence, it decreases the reactivity of the solution.

Also, It can be noted that strong acid and weak acid both can be diluted and referred to as dilute acid.

The quantity of solute in the acid solution relative to the amount of solvent determines whether an acid is concentrated or diluted.

Concentrated acids react with metals and corrode them since they are so aggressive in nature as compared to dilute acids. As a result, they are not kept in metallic vessels. But dilute acids can be easily stored in metallic vessels.

Difference between Concentrated Acids and Dilute Acids:

Concentrated acid	Diluted Acids
An acid that has an extremely high acid-to-water ratio is considered to be concentrated.	An acid that has an extremely high water-to-acid ratio is considered to be diluted.
They have a large number of ions readily available.	There are few ions in their solution.
Their mass percentage in the solution is larger.	Their mass percentage in the solution is smaller.
Water can be used to dilute the concentrated acid.	Acids with higher water concentrations are said to be diluted acids.
Examples: 98% mass of concentrated sulfuric acid.	Example: Vinegar is a diluted acetic acid.

Practice Problems:

Q1. Which of the following acids can be classified under the category of dilute acids?

HNO₃
HCOOH
H₂CO₃
All of these

Answer: (D)

Solution: In given options, HNO₃ is a strong acid and HCOOH & H₂CO₃ are weak acids.

It should be noted that dilute acid can be used to describe both strong and weak acids. Whether an acid is concentrated or diluted depends on the ratio of the solute to the solvent in the acid solution. As no concentration is given here. Hence, all the given acids can be categorized under the category of dilute acids.

Hence, option (D) is the correct answer.

Q2. Which of the following acids can be classified under the category of most concentrated acids?

2 M of HCl
0.2 M of H₂SO₄
2 M of H₂SO₄
All of these

Answer: (C)

Solution: Whether an acid is concentrated or diluted depends on the ratio of the solute to the solvent in the acid solution. So, the more the solute-to-solvent ratio of the given acid, the more concentrated is the acid.

In Option (A), 2 M of HCl refers to 2 moles of H⁺ ions present in 1 Litre solution.

In Option (B), 0.2 M of H₂SO₄ refers to 0.4 moles of H⁺ ions present in 1 Litre solution.

In Option (C), 2 M of H₂SO₄ refers to 4 moles of H⁺ ions present in 1 Litre solution.

As highest concentration is present in 4 moles of H⁺ ions . Hence, most concentrated acid among the given options is 2 M of H₂SO₄.

Hence, the correct answer is an option (C).

Q3. Which of the following acids can be categorized as the most dilute strong acids?

0.2 M of H₂SO₄
0.2 M of HCN
0.2 M of HCl
All of these

Answer: (C)

Solution: The ratio of the solute to the solvent in the acid solution describes whether an acid is concentrated or diluted. So, the less the solute-to-solvent ratio of the given acid, the more diluted is the acid.

In the given options, H₂SO₄ and HCl are strong acids and HCN is a weak acid and it is specifically given in the question that acid should be strong. Hence option (B) is automatically excluded.

In Option (A), 0.2 M of H₂SO₄refers to 0.4 moles of H⁺ ions present in 1 Litre solution.

In Option (C), 0.2 M of HCl refers to 0.2 moles of H⁺ ions present in 1 Litre solution.

As least concentration is present in 0.2 moles of H⁺ ions. Hence, the most diluted acid among the given options is 0.2 M of HCl.

Hence, the correct answer is an option (C).

Q4. Which of the following acids can be categorized as the least diluted weak acids?

1 M of HCOOH
1 M of HCN
1 M of CH₃COOH
All of these

Answer: (D)

Solution: The ratio of the solute to the solvent in the acid solution describes whether an acid is concentrated or diluted. So, the more the solute-to-solvent ratio of the given acid, the less diluted is the acid.

In the given options, HCOOH, HCN and CH₃COOH are weak monobasic acids.

Also, the concentration of all the given weak acids is the same. Hence, all the acids are having approximately the same amount of solute to solvent ratio which means all the given acids are having almost the same extent of dilution.

Hence, the correct answer is an option (D).

Frequently Asked Questions-FAQs:

1. Why is the nature and concept of a weak acid and dilute acid not the same?
Answer: Concentrated acid is that with a higher solute concentration, and diluted acid is that with a lower solute concentration. Water can be added to conc HNO₃, a strong acid, to dilute it, but the resultant acid is still dilute strong acid. It can not be depicted as a weak acid. Hence, the concept of a weak acid and dilute is entirely different.

2. What are Arrhenius Acids?
Answer: That substance is known as Arrhenius acid which dissociates in water to give hydrogen ions (H⁺).

For example HCl, H2SO4, HClO4, CH₃COOH etc dissociates to give H⁺ion and X-ion

HX(aq)+H₂O (l)H₃+O(aq)+X^-(aq)

3. What are Lewis Acids?
Answer: A substance which does not have Hydrogen or release proton H⁺ but accepts an electron pair called a Lewis acid.

Example of Lewis Acid: BF₃, AlCl₃, H⁺etc.

4. What are the factors that affect the rate of reaction of acids?
Answer: There are basically three major factors that affect the rate of reaction and these are-

(i) Concentration of acid
(ii) Type of metal and its surface area
(iii) Temperature