Chapter 19 Acids, Bases, and Salts – Flashcards
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| What are the properties of acids and bases? |
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| acids taste sour, will change the color of an acid-base indicator, and can be strong or weak electrolytes in aqueous solution. |
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| How did Arrhenius define an acid and a base? |
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| Arrhenius said that acids are hydrogen-containing compounds that ionize to yield hydrogen ions (H+) in aqueous solution. He also said that bases are compounds that iionize to yield hydroxide ions (OH-) in aqueous solution. |
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| What distinguishes an acid from a base in the Bronsted-Lowry theory? |
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| the Bronsted-Lowry theory defines an acid as a hydrogen-ion donor, and a base as a hydrogen-ion acceptor. |
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| How did Lewis define an acid and a base? |
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| Lewis proposed that an acid accepts a pair of electrons during a reaction, while a base donates a pair of electrons. |
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| Monoprotic acids |
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| acids that contain one ionizable hydrogen, such as nitric acid (HNO3). |
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| Diprotic acids |
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| acids that contain two ionizable hydrogens, such as sulfric acid (H2SO4). |
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| Triprotic acids |
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| acids that contain three ionizable hydrogens, such as phosphoric acid (H3PO4). |
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| Conjugate acid |
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| the particle formed when a base gains a hydrogen ion. |
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| Conjugate base |
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| the particle that remains when an acid has donated a hydrogen ion. |
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| Conjugate acid-base pair |
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| consists of two substances related by the loss or gain of a single hydrogen ion. |
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| Hydronium ion (H3O+) |
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| a water molecule that gains a hydrogen ion and becomes positively charged. |
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| Amphoteric |
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| a substance that can act as both an acid and a base. |
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| Lewis acid |
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| a substance that can accept a pair of electrons to form a covalent bond. |
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| Lewis base |
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| a substance that can donate a pair of electrons to form a covalent bond. |
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| How are [H+] and [OH-] related in a aqueous solution? |
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| for aqueous solutions, the product of the hydrogen-ion concentration and the hydroxide-ion concentration equals 1.0x10^-14. |
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| How is the hydrogen-ion concentration used to classify a solution as neutral, acidic, or basic? |
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| a solution in which [H+] is greater than 1x10^-7M has a pH less than 7.0 and is acidic. the pH of pure water or a neutral aqueous solution is 7.0. a solution with a pH greater than 7 is basic and has a [H+] of less than 1x10^-7M. |
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| What is the most important characteristic of an acid-base indicator? |
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| an indicator is a valuable tool for measuring pH because its acid form and base form have different colors in solution. |
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| Self-ionizing |
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| the reaction in which water molecules produce ions. |
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| Neutral solution |
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| any aqueous solution in which [H+] and [OH-] are equal. |
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| Ion-product constant for water (Kw) |
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| the product of the concentrations of the hydrogen ions and hydroxide ioons in water. |
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| Acidic solution |
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| one in which [H+] is greater than [OH-] |
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| Basic solution |
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| one in which [H+] is less than [OH-]. |
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| Alkaline solutions |
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| another name for basic solutions. |
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| pH |
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| the negative logarithm of the hydrogen-ion concentration. |
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| How does the value of an acid dissociation constant relate to the strength of an acid? |
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| weak acids have small Ka values. The stronger an acid is, the larger its Ka value. |
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| How can you calculate an acid dissociation constant (Ka) of a weak acid? |
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| to find the Ka of a weak acid or the Kb of a weak base, substitute the measured concentrations of all the substances present at equilibrium into the expression for Ka or Kb. |
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| Strong acids |
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| completely ionized in aqueous solution. |
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| Weak acids |
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| ionize only slightly in aqueous solution. |
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| Acid dissociation constant (Ka) |
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| the ratio of the concentration of the dissociation (or ionized) form of an acid to the concentration of the undissociated (nonioinized) form. |
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| Strong bases |
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| dissociate completely into metal ions and hydroxide ions in aqueous solution. |
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| Weak bases |
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| react with water to form the hydroxide ion and the conjugate acid of the base. |
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| Base dissociation constant (Kb) |
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| the ratio of the concentration of the conjugate acid times the concentration of the hydroxide ion to the concentration of the base. |
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| What are the products of the reaction of an acid with a base? |
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| in general, the reaction of an acid with a base produces water and one of a class of compounds called salts. |
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| What is the endpoint of a titration? |
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| the point of neutralization is the end point of the titration. |
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| Neutralization reactions |
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| reactions in which an acid and a base react in an aqueous solution to produce a salt and water. |
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| Equivalence point |
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| when the number of moles of hydrogen ions equals the number of moles of hydroxide ions. |
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| Titration |
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| the process of adding a known amount of solution of known concentration to determine the concentration of another solution. |
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| Standard solution |
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| the solution of known concentration. |
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| End point |
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| the point at which the indicator changes color. |
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| When is the solution of a salt acidic or basic? |
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| in general, salts that produce acidic solutions contain positive ions that release protons to water. Salts that produce basic solutions contain negative ions that attract protons from water. |
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| What are the components of a buffer? |
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| a buffer is a solution of a weak acid and one of its slats, or a solution of a weak base and one of its salts. |
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| Salt hydrolysis |
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| the cations or anions of a dissociation salt remove hydrogen ions from or donate hydrogen ions to water. |
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| Buffer |
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| a solution in which the pH remains relatively constant when small amounts of acid or base are added. |
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| Buffer capacity |
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| the amount of acid or base that can be added to a buffer solution before a significant change in pH occurs. |
