What is the Brønsted-Lowry definition of an acid and base?

A. NH4SO4

B. (NH4)2SO4

C. (NH4)SO4

D. (NH3)2SO4

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).

A. Because it does not react with water

B. Because it does not contain hydrogen ions (H+)

C. Because it contains hydrogen ions but not chloride ions (Cl-)

D. Because hydrogen is bonded to chlorine in dry HCl and not dissociated

A) Because it does not react with water: While dry hydrogen chloride gas does not react with water, the absence of this reaction does not inherently determine its acidity. Acidity is determined by the presence of hydrogen ions in solution.

B) Because it does not contain hydrogen ions (H+): Dry hydrogen chloride gas does not contain free hydrogen ions, which are characteristic of acidic solutions. However, the absence of hydrogen ions alone does not explain why dry hydrogen chloride gas is not acidic.

C) Because it contains hydrogen ions but not chloride ions (Cl-): Dry hydrogen chloride gas does not contain free chloride ions, but the presence of hydrogen ions is crucial for acidity. However, the absence of chloride ions alone does not fully explain why dry hydrogen chloride gas is not acidic.

D) Because hydrogen is bonded to chlorine in dry HCl and not dissociated (Correct Answer): Dry hydrogen chloride gas does not dissociate into hydrogen ions (H+) and chloride ions (Cl-) because there is no water present to facilitate dissociation. Therefore, it does not exhibit acidic properties in the absence of dissociation.

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

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.

A. A gas formed during a chemical reaction

B. A liquid formed when two aqueous solutions react

C. A solid formed when two aqueous solutions react

D. A solution formed during a chemical reaction

A) A gas formed during a chemical reaction: While gases can indeed be produced during chemical reactions, a precipitate specifically refers to a solid that forms during a reaction.

B) A liquid formed when two aqueous solutions react: Precipitates are not liquids. They are solids that are formed when certain ions combine to form an insoluble compound.

C) A solid formed when two aqueous solutions react (Correct Answer): A precipitate is indeed a solid substance that forms when two aqueous solutions react and certain ions combine to create an insoluble compound.

D) A solution formed during a chemical reaction: A precipitate is not a solution. It is the solid product that separates out of a solution during a chemical reaction due to its limited solubility.

A. Salt and water

B. Carbon dioxide and water

C. Oxygen gas and water

D. Salt and hydrogen gas

A) Salt and water: This reaction occurs when an acid reacts with a metal hydroxide or a metal oxide, not with a metal carbonate or metal hydrogen carbonate.

B) Carbon dioxide and water (Correct Answer): When an acid reacts with a metal carbonate or metal hydrogen carbonate, carbon dioxide gas is produced along with water and a salt. The carbonates decompose into carbon dioxide gas, water, and a salt when reacting with acids.

C) Oxygen gas and water: This reaction is not typical when an acid reacts with a metal carbonate or metal hydrogen carbonate. Metal carbonates and metal hydrogen carbonates generally do not produce oxygen gas when reacting with acids.

D) Salt and hydrogen gas: This reaction occurs when an acid reacts with a metal, not with a metal carbonate or metal hydrogen carbonate. When metals react with acids, hydrogen gas is typically produced along with a salt.

A. Oxidation

B. Reduction

C. Neutralization

D. Precipitation

A) Oxidation: Sulfuric acid and ammonia do not participate in an oxidation-reduction reaction, where one substance loses electrons (oxidation) and another gains electrons (reduction).

B) Reduction: Sulfuric acid and ammonia do not participate in an oxidation-reduction reaction, so reduction is not the correct type of reaction.

C) Neutralization (Correct Answer): When sulfuric acid reacts with ammonia, a neutralization reaction occurs. The acidic hydrogen ions (H+) from sulfuric acid react with the basic ammonia molecules (NH3) to form ammonium ions (NH4+) and sulfate ions (SO4^2-), resulting in the formation of an ammonium sulfate salt.

D) Precipitation: A precipitation reaction occurs when two solutions react to form an insoluble solid (precipitate). However, sulfuric acid and ammonia do not form an insoluble product when they react. Therefore, precipitation is not the correct type of reaction for this scenario.

A. Filtration

B. Distillation

C. Decantation

D. Chromatography

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.

A. Because it reacts vigorously with acids

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

C. Because in solution it fully dissociates into K+ and OH-

D. Because it forms insoluble precipitates with metal cations

A) Because it reacts vigorously with acids: While KOH does react with acids to form salts and water, the strength of an alkali is not solely determined by its reactivity with acids.

B) Because it forms a basic solution when dissolved in water: This statement is true, but it does not fully explain why KOH is considered a strong alkali. Many compounds can form basic solutions when dissolved in water.

C) Because in solution it fully dissociates into K+ and OH- (Correct Answer): KOH is considered a strong alkali because it fully dissociates in aqueous solution into potassium ions (K+) and hydroxide ions (OH-). This dissociation leads to a high concentration of hydroxide ions in solution, making it strongly alkaline.

D) Because it forms insoluble precipitates with metal cations: This statement describes the formation of insoluble hydroxide precipitates when alkali solutions are added to solutions of metal salts. However, it does not fully explain why KOH itself is considered a strong alkali.

A. To increase the rate of reaction

B. To decrease the rate of reaction

C. To prevent the formation of byproducts

D. To decrease the energy of activation

A) To increase the rate of reaction (Correct Answer): Heating the sulfuric acid increases the kinetic energy of the particles, leading to more frequent and energetic collisions between the reactant particles. This, in turn, increases the rate of reaction between copper oxide and sulfuric acid, facilitating the production of copper sulfate.

B) To decrease the rate of reaction: Heating typically increases the rate of reaction by providing more energy for particles to overcome the activation energy barrier. Decreasing the temperature would slow down the reaction, which is not the intended outcome in this scenario.

C) To prevent the formation of byproducts: While heating may influence the selectivity of reactions and the formation of byproducts in some cases, the primary purpose of heating sulfuric acid in this context is to increase the rate of reaction rather than to prevent the formation of byproducts.

D) To decrease the energy of activation: Heating increases the energy of particles, helping them overcome the energy barrier required for the reaction to occur. Therefore, heating sulfuric acid would increase the energy of activation rather than decrease it.

A. Acids are electron donors and bases are electron acceptors.

B. Acids are proton donors and bases are proton acceptors.

C. Acids are proton acceptors and bases are proton donors.

D. Acids are compounds that increase the concentration of hydroxide ions in solution and bases are compounds that increase the concentration of hydrogen ions in solution.

A) Acids are electron donors and bases are electron acceptors: This statement describes the Lewis definition of acids and bases, which focuses on the transfer of electron pairs, rather than the Brønsted-Lowry definition, which involves the transfer of protons.

B) Acids are proton donors and bases are proton acceptors. (Correct Answer): According to the Brønsted-Lowry definition, an acid is a substance that donates a proton (H+ ion), while a base is a substance that accepts a proton.

C) Acids are proton acceptors and bases are proton donors: This statement incorrectly describes the roles of acids and bases according to the Brønsted-Lowry definition. Acids donate protons, while bases accept protons.

D) Acids are compounds that increase the concentration of hydroxide ions in solution and bases are compounds that increase the concentration of hydrogen ions in solution: This statement does not accurately represent the Brønsted-Lowry definition. Acids and bases are defined based on their behavior regarding proton transfer, not changes in ion concentration.