(a)
Interpretation:
Whether the statement, “The solution of a weak electrolyte is a poor conductor of electricity” is true or false is to be stated.
Concept introduction:
Solutions of substances in which the ions are the conducting species are called electrolytes. The ionization depends on the nature of the substance. Some substances are more ionized in solution and conduct more electricity. Other substances are ionized to a lesser extent and conduct less electricity. The ability of a solution to conduct electricity depends on the number of ions present in the solution.
Answer to Problem 80E
The statement, “The solution of a weak electrolyte is a poor conductor of electricity” is true.
Explanation of Solution
Strong electrolytes produce more number of ions in the solution and are good conductors of electricity. Weak electrolytes produce less number of ions in the solution and are bad conductors of electricity. Therefore, the statement, “The solution of a weak electrolyte is a poor conductor of electricity” is true.
The statement, “The solution of a weak electrolyte is a poor conductor of electricity” is true.
(b)
Interpretation:
Whether the statement, “Ions must be present if a solution conducts electricity” is true or false is to be stated.
Concept introduction:
Solutions of substances in which the ions are the conducting species are called electrolytes. The ionization depends on the nature of the substance. Some substances are more ionized in solution and conduct more electricity. Other substances are ionized to a lesser extent and conduct less electricity. The ability of a solution to conduct electricity depends on the number of ions present in the solution.
Answer to Problem 80E
The statement, “Ions must be present if a solution conducts electricity” is true.
Explanation of Solution
Solid ionic compound is formed by positive and negative ions which are held in a fixed position. When this compound is dissolved in water, the ions become free to move and conduct electricity. Therefore, the statement, “Ions must be present if a solution conducts electricity” is true.
The statement, “Ions must be present if a solution conducts electricity” is true.
(c)
Interpretation:
Whether the statement, “Ions are the major species in a solution of a soluble ionic compound” is true or false is to be stated.
Concept introduction:
Ionic compounds are made up of equal number of positive and negative ions held together at fixed positions. They have high melting points and are good conductors of electricity.
Answer to Problem 80E
The statement, “Ions are the major species in a solution of a soluble ionic compound” is true.
Explanation of Solution
Solid ionic compound is formed by positive and negative ions held together at fixed positions. When an ionic compound is dissolved in water, the ions become free to move. Therefore, ions are the major species in a solution of a soluble ionic compound. Therefore, the statement, “Ions are the major species in a solution of a soluble ionic compound” is true.
The statement, “Ions are the major species in a solution of a soluble ionic compound” is true.
(d)
Interpretation:
Whether the statement, “There are no ions present in the solution of a weak acid” is true or false is to be stated.
Concept introduction:
Acids are compounds which release a proton or hydrogen ion when present in a solution. Acids are classified as strong or weak on the basis of extent of their ionization.
Answer to Problem 80E
The statement, “There are no ions present in the solution of a weak acid” is false.
Explanation of Solution
A weak acid undergoes slight ionization in solution. The major species present in a solution of weak acid is the unionized molecular species. However some ions are present as minor species. Therefore, the statement, “There are no ions present in the solution of a weak acid” is false.
The statement, “There are no ions present in the solution of a weak acid” is false.
(e)
Interpretation:
Whether the statement, “Only seven "important" acids are weak” is true or false is to be stated.
Concept introduction:
Acids are compounds which release a proton or hydrogen ion when present in a solution. Acids are classified as strong or weak on the basis of extent of their ionization.
Answer to Problem 80E
The statement, “Only seven "important" acids are weak” is false.
Explanation of Solution
Only seven acids are accepted as strong acids. They are: nitric acid, sulfuric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, chloric acid and perchloric acid. All the rest of the acids are weak. Therefore, the statement, “Only seven "important" acids are weak” is false.
The statement, “Only seven "important" acids are weak” is false.
(f)
Interpretation:
Whether the statement, “Hydrofluoric acid, which is used to etch glass, is a strong acid” is true or false is to be stated.
Concept introduction:
Acids are compounds which release a proton or hydrogen ion when present in a solution. Acids are classified as strong or weak on the basis of extent of their ionization.
Answer to Problem 80E
The statement, “Hydrofluoric acid, which is used to etch glass, is a strong acid” is false.
Explanation of Solution
Hydrofluoric acid is a corrosive acid, but it is not included in the list of the seven strong acids. Therefore, it is not a strong acid. Therefore, the statement, “Hydrofluoric acid, which is used to etch glass, is a strong acid” is false.
The statement, “Hydrofluoric acid, which is used to etch glass, is a strong acid” is false.
(g)
Interpretation:
Whether the statement, “Spectators are included in a net ionic equation” is true or false is to be stated.
Concept introduction:
Answer to Problem 80E
The statement, “Spectators are included in a net ionic equation” is false.
Explanation of Solution
A net ionic equation indicates the exact chemical change that occurs during a reaction. Spectator ions are the ions which do not undergo any change during the reaction. Therefore, they are not included in the net ionic equation. Therefore, the statement, “Spectators are included in a net ionic equation” is false.
The statement, “Spectators are included in a net ionic equation” is false.
(h)
Interpretation:
Whether the statement, “A net ionic equation for a reaction between an element and an ion is the equation for a single-replacement
Concept introduction:
Chemical reactions are represented by chemical equations. In a chemical equation the reactants are represented on the left of the arrow while the products are represented on the right of the arrow.
Answer to Problem 80E
The statement, “A net ionic equation for a reaction between an element and an ion is the equation for a single-replacement redox reaction” is true.
Explanation of Solution
Elements are in zero oxidation state and have no counter ions to exchange with the other reactant. In an ionic equation, the elements in zero oxidation state undergo oxidation or reduction to form respective ions. At the same time, the positive ions accept or lose electrons to undergo oxidation or reduction. Therefore, it is a single replacement redox reaction. Therefore, the statement, “A net ionic equation for a reaction between an element and an ion is the equation for a single-replacement redox reaction” is true.
The statement, “A net ionic equation for a reaction between an element and an ion is the equation for a single-replacement redox reaction” is true.
(i)
Interpretation:
Whether the statement, “A compound that is insoluble forms a precipitate when its ions are combined” is true or false is to be stated.
Concept introduction:
Chemical reactions are represented by chemical equations. In a chemical equation the reactants are represented on the left of the arrow while the products are represented on the right of the arrow. If the product formed is an insoluble compound, the reaction is termed as precipitation reaction.
Answer to Problem 80E
The statement, “A compound that is insoluble forms a precipitate when its ions are combined” is false.
Explanation of Solution
Insoluble compounds do not ionize in water. For the formation of precipitate, the combination of ions is necessary. Therefore, only a soluble compound can form a precipitate. Therefore, the statement, “A compound that is insoluble forms a precipitate when its ions are combined” is false.
The statement, “A compound that is insoluble forms a precipitate when its ions are combined” is false.
(j)
Interpretation:
Whether the statement, “Precipitation and molecule-formation reactions are both ion-combination reactions having double-replacement conventional equations” is true or false is to be stated.
Concept introduction:
Chemical reactions are represented by chemical equations. In a chemical equation the reactants are represented on the left of the arrow while the products are represented on the right of the arrow. If the product formed is an insoluble compound, the reaction is termed as precipitation reaction. If the product formed, does not ionize, it is termed as molecule-formation reaction. Double replacement reactions are those in which exchange of cations and anions of both the reactants takes place. In it the ions appear to change partners.
Answer to Problem 80E
The statement, “Precipitation and molecule-formation reactions are both ion-combination reactions having double-replacement conventional equations” is true.
Explanation of Solution
In precipitation reaction, the cation of one of the reactant reacts with the anion of the other reactant and vice-a-versa to form an insoluble compound. In molecular formation reactions, the exchange of cations and anions between reactants takes place to form a molecular product which does not ionize. Therefore, they both are double replacement conventional equations. Therefore, the statement, “Precipitation and molecule-formation reactions are both ion-combination reactions having double-replacement conventional equations” is true.
The statement, “Precipitation and molecule-formation reactions are both ion-combination reactions having double-replacement conventional equations” is true.
(k)
Interpretation:
Whether the statement, “Neutralization is a special case of a molecule-formation reaction” is true or false is to be stated.
Concept introduction:
Chemical reactions are represented by chemical equations. In a chemical equation, the reactants are represented on the left of the arrow while the products are represented on the right of the arrow. If the product formed, does not ionize, it is termed as molecule-formation reaction.
Answer to Problem 80E
The statement, “Neutralization is a special case of a molecule-formation reaction” is true.
Explanation of Solution
In molecular formation reactions, the product formed is either water or a weak acid. In a neutralization reaction, the molecular compound formed is always water. Weak acid is not formed in a neutralization reaction. Therefore, neutralization is a special case of molecule-formation reaction in which product is always water. Therefore, the statement, “Neutralization is a special case of a molecule-formation reaction” is true.
The statement, “Neutralization is a special case of a molecule-formation reaction” is true.
(l)
Interpretation:
Whether the statement, “One product of a molecule-formation reaction is a strong acid” is true or false is to be stated.
Concept introduction:
Chemical reactions are represented by chemical equations. In a chemical equation, the reactants are represented on the left of the arrow while the products are represented on the right of the arrow. If the product formed, does not ionize, it is termed as molecule-formation reaction.
Answer to Problem 80E
The statement, “One product of a molecule-formation reaction is a strong acid” is false.
Explanation of Solution
In molecular formation reactions, the product formed is either water or a weak acid. So, strong acid is not formed as a product of molecule-formation reaction. Therefore, the statement, “One product of a molecule-formation reaction is a strong acid” is false.
The statement, “One product of a molecule-formation reaction is a strong acid” is false.
(m)
Interpretation:
Whether the statement, “Ammonium hydroxide is a possible product of a molecule-formation reaction” is true or false is to be stated.
Concept introduction:
Chemical reactions are represented by chemical equations. In a chemical equation, the reactants are represented on the left of the arrow while the products are represented on the right of the arrow. If the product formed, does not ionize, it is termed as molecule-formation reaction.
Answer to Problem 80E
The statement, “One Ammonium hydroxide is a possible product of a molecule-formation reaction” is false.
Explanation of Solution
In molecular formation reactions, the product formed is either water or a weak acid. The product formed in molecule formation reaction does not ionize. Ammonium hydroxide is a salt and therefore, it can undergo complete ionization. Therefore, it cannot be a possible product of molecule-formation reaction.. Therefore, the statement, “Ammonium hydroxide is a possible product of a molecule-formation reaction” is false.
The statement, “Ammonium hydroxide is a possible product of a molecule-formation reaction” is false.
(n)
Interpretation:
Whether the statement, “Carbon is changed to carbon dioxide when a carbon-containing compound burns completely” is true or false is to be stated.
Concept introduction:
Chemical reactions are represented by chemical equations. In a chemical equation, the reactants are represented on the left of the arrow while the products are represented on the right of the arrow. If the product formed, does not ionize, it is termed as molecule-formation reaction.
Answer to Problem 80E
The statement, “Carbon is changed to carbon dioxide when a carbon-containing compound burns completely” is true.
Explanation of Solution
Substances are said to burn when they react with atmospheric oxygen completely to produce carbon dioxide and water. Carbon containing organic compounds reacts with the oxygen to form carbon dioxide. Therefore, statement, “Carbon is changed to carbon dioxide when a carbon-containing compound burns completely” is true.
The statement, “Carbon is changed to carbon dioxide when a carbon-containing compound burns completely” is true.
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Chapter 9 Solutions
Introduction to Chemistry, Special Edition
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