Why is ethanoic acid a weak acid?

A. Because it reacts slowly with bases

B. Because it forms a basic solution when dissolved in water

C. Because it only partially dissociates in solution

D. Because it has a low pH value

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Answer Explanation:

Rationale for each choice:

A) Because it reacts slowly with bases: The rate of reaction with bases does not determine whether an acid is weak or strong. Ethanoic acid's reaction rate with bases is not a primary factor in its classification as a weak acid.

B) Because it forms a basic solution when dissolved in water: This statement is incorrect. Ethanoic acid is an acid and forms acidic solutions when dissolved in water.

C) Because it only partially dissociates in solution (Correct Answer): Ethanoic acid is considered a weak acid because it only partially dissociates into hydrogen ions (H+) and acetate ions (CH3COO-) in solution. This partial dissociation results in a lower concentration of hydrogen ions compared to strong acids.

D) Because it has a low pH value: While weak acids generally have higher pH values compared to strong acids, the pH value alone does not determine whether an acid is weak or strong. Ethanoic acid's weak acidity is primarily attributed to its partial dissociation in solution, rather than its pH value.

Therefore, the Correct Answer is C.

More Questions on C2 Acids, Bases and Salts

Question 1:

What is produced when an acid reacts with ammonia?

A. Water

B. Ammonia and Water

C. Ammonium salt

D. Hydrogen gas

The Correct Answer is C.

A) Water: Water is not typically produced when an acid reacts with ammonia. Water may be present in the reaction mixture, but it is not a direct product of the reaction between the acid and ammonia.

B) Ammonium chloride: Water and ammonia  are not typically produced when an acid reacts with ammonia. 

C) Ammonium salt (Correct Answer): When an acid reacts with ammonia, an ammonium salt is typically formed. The specific ammonium salt produced depends on the acid used in the reaction.

D) Hydrogen gas: Hydrogen gas is not typically produced when an acid reacts with ammonia. The reaction between an acid and ammonia does not involve the liberation of hydrogen gas.


Question 2:

What is the formula of ammonium sulfate?

A. NH4SO4

B. (NH4)2SO4

C. (NH4)SO4

D. (NH3)2SO4

The Correct Answer is B.

A) NH4SO4: This formula suggests a compound where one ammonium ion is combined with one sulfate ion, which is not the correct composition of ammonium sulfate.

B) (NH4)2SO4 (Correct Answer): This formula correctly represents ammonium sulfate, indicating that it consists of two ammonium ions (NH4+) and one sulfate ion (SO4^2-).

C) (NH4)SO4: This formula suggests a compound with one ammonium ion combined with one sulfate ion, which is not the correct composition of ammonium sulfate.

D) (NH3)2SO4: This formula suggests a compound where two ammonia molecules (NH3) are combined with one sulfate ion, which is incorrect. Ammonium sulfate contains ammonium ions (NH4+), not ammonia molecules (NH3).


Question 3:

When acids and bases react together, we call this a:

A. Neutralization reaction.

B. Decomposition reaction.

C. Synthesis reaction.

D. Redox reaction.

The Correct Answer is A.

A. Neutralization reaction. (Correct Answer): When acids and bases react, they undergo a neutralization reaction, resulting in the formation of water and a salt. In this reaction, the acidic properties of the acid are neutralized by the basic properties of the base.

B. Decomposition reaction: A decomposition reaction involves the breakdown of a compound into smaller substances. It does not typically describe the reaction between acids and bases.

C. Synthesis reaction: A synthesis reaction involves the formation of a compound from simpler substances. It does not typically describe the reaction between acids and bases.

D. Redox reaction: A redox reaction involves the transfer of electrons between reactants. While redox reactions can occur in certain acid-base reactions, they are not specific to the reaction between acids and bases. The typical reaction between acids and bases involves proton transfer rather than electron transfer. Therefore, "neutralization reaction" is a more specific and accurate term for this type of reaction.


Question 4:

A solution with a pH of 5.0 _____.

A. has a hydrogen-ion concentration of 5.0M

B. is neutral

C. has a hydroxide-ion concentration of 1 x 10 –9 M

D. None of the above

The Correct Answer is D.

a. is basic: Incorrect. Solutions with pH values less than 7 are acidic, not basic. A pH of 5.0 indicates an acidic solution.

b. has a hydrogen-ion concentration of 5.0M: Incorrect. The pH value does not directly provide information about the concentration of hydrogen ions. pH is a logarithmic scale that measures the concentration of hydrogen ions in a solution.

c. is neutral: Incorrect. Solutions with a pH of 7 are considered neutral. A pH of 5.0 indicates an acidic solution.

d. has a hydroxide-ion concentration of 1 x 10 –9 M: Incorrect. This statement relates to the calculation of hydroxide-ion concentration in a neutral solution using the Kw value (the ion product of water). It does not directly pertain to the pH value of the solution.


Question 5:

:pH is a measure of how acidic or basic a substance is. The pH scale ranges from:

A. 0–7

B. 7–14

C. 0–14

D. 1–10

The Correct Answer is C.

A. 0–7: This range corresponds to acidic solutions on the pH scale. A pH value below 7 indicates acidity.

B. 7–14: This range corresponds to basic solutions on the pH scale. A pH value above 7 indicates alkalinity.

C. 0–14 (Correct Answer): The pH scale ranges from 0 to 14, covering the entire spectrum of acidity and alkalinity. A pH value of 7 is considered neutral, while values below 7 indicate acidity and values above 7 indicate alkalinity.

D. 1–10: This range does not encompass the full range of the pH scale. The pH scale extends beyond 10 for alkaline solutions and below 1 for highly acidic solutions. Therefore, this choice is incorrect.


Question 6:

How can solid lead iodide be separated from solution?

A. Filtration

B. Distillation

C. Decantation

D. Chromatography

The Correct Answer is A.

A) Filtration: Solid lead iodide can be separated from the solution using filtration. Filtration involves passing the mixture through a filter paper or porous material, allowing the solid particles to be retained while the liquid passes through.

B) Distillation: Distillation is a process used to separate components of a mixture based on differences in their boiling points. It is not typically used to separate solid lead iodide from a solution.

C) Decantation: Decantation involves carefully pouring off the liquid portion of a mixture, leaving the solid behind. While it can be used to separate solid and liquid phases, it may not be as effective as filtration for separating fine solid particles like lead iodide.

D) Chromatography: Chromatography is a technique used to separate and analyze mixtures based on differences in the components' distribution between two phases: a stationary phase and a mobile phase. It is not typically used for separating solid lead iodide from a solution.


Question 7:

How can copper sulfate crystals be separated from copper sulfate solution?

A. Filtration

B. Distillation

C. Decantation

D. Evaporation

The Correct Answer is D.

A) Filtration: Filtration is not suitable for separating dissolved substances from a solution. It is typically used to separate solid particles from a liquid mixture.

B) Distillation: Distillation is a process used to separate components of a mixture based on differences in their boiling points. It is not typically used to separate solid crystals from a solution.

C) Decantation: Decantation involves pouring off the liquid portion of a mixture, leaving the solid behind. While it can be used to separate solid and liquid phases, it may not effectively separate dissolved copper sulfate from the solution.

D) Evaporation (Correct Answer): Evaporation involves heating the solution to allow the solvent (water) to vaporize, leaving behind the solute (copper sulfate) as solid crystals. This process is commonly used to obtain solid crystals from a solution.


Question 8:

Which one of the following must be added to dilute hydrochloric acid to produce hydrogen?

A. Iron

B. Iron sulfide

C. Copper chloride

D. Sulfur

The Correct Answer is A.

A. Iron (Correct Answer): Iron can react with hydrochloric acid to produce hydrogen gas according to the following reaction:

2HCl + Fe => FeCl2 + H2

So, adding iron to dilute hydrochloric acid would produce hydrogen gas.

B. Iron sulfide: Iron sulfide may react with hydrochloric acid, but it does not directly produce hydrogen gas. The reaction would likely produce hydrogen sulfide gas instead.

C. Copper chloride: Copper chloride does not react with hydrochloric acid to produce hydrogen gas. The reaction between copper chloride and hydrochloric acid would likely produce copper chloride and hydrogen chloride gas.

D. Sulfur: Sulfur does not react with hydrochloric acid to produce hydrogen gas. The reaction between sulfur and hydrochloric acid would likely produce hydrogen sulfide gas.


Question 9:

What do plants use the nitrogen in fertilizers for?

A. To provide energy for photosynthesis

B. To build cellulose in cell walls

C. To build amino acids and proteins

D. To regulate water uptake

The Correct Answer is D.

A) To provide energy for photosynthesis: While nitrogen is essential for various metabolic processes in plants, it is not directly involved in providing energy for photosynthesis. Instead, plants use sunlight to convert carbon dioxide and water into glucose during photosynthesis.

B) To build cellulose in cell walls: Nitrogen is not directly involved in the synthesis of cellulose, which is primarily composed of glucose units. Cellulose synthesis mainly relies on carbon and hydrogen, which are obtained from carbon dioxide and water during photosynthesis.

C) To build amino acids and proteins: Plants use nitrogen from fertilizers to synthesize amino acids and proteins. Nitrogen is a crucial component of amino acids, the building blocks of proteins, which are essential for plant growth, development, and various physiological processes.

D) To regulate water uptake (Correct Answer): Nitrogen plays a role in regulating various physiological processes in plants, including water uptake. It affects the osmotic potential of plant cells and helps regulate the movement of water and nutrients within the plant.


Question 10:

Why is NaCl neutral?

A. Because it contains both hydrogen and hydroxide ions in equal amounts

B. Because it contains hydrogen ions (H+) and hydroxide ions (OH-) in equal amounts

C. Because it does not contain any hydrogen or hydroxide ions

D. Because it dissociates completely in water

The Correct Answer is C.

Rationale for each choice:

A) Because it contains both hydrogen and hydroxide ions in equal amounts: This statement is incorrect. NaCl (sodium chloride) does not contain hydrogen or hydroxide ions. It dissociates into sodium ions (Na+) and chloride ions (Cl-) in water, not hydrogen or hydroxide ions.

B) Because it contains hydrogen ions (H+) and hydroxide ions (OH-) in equal amounts: This statement is incorrect. NaCl does not contain hydrogen or hydroxide ions. In aqueous solution, NaCl dissociates into sodium ions and chloride ions, not hydrogen or hydroxide ions.

C) Because it does not contain any hydrogen or hydroxide ions (Correct Answer): NaCl is a neutral compound composed of sodium ions (Na+) and chloride ions (Cl-). It does not contain any hydrogen or hydroxide ions, so it is neutral in aqueous solution.

D) Because it dissociates completely in water: NaCl does dissociate in water, but its dissociation does not involve the generation of hydrogen or hydroxide ions. It dissociates into sodium ions and chloride ions, which do not contribute to the pH of the solution. Therefore, the completeness of dissociation does not determine its neutrality.