When a water molecule accepts a proton, it becomes a hydronium ion, H3O+.
Missing Word
hydronium
The hydronium ion, H3O+, is the form a proton takes in water. Acidic solutions have a higher concentration of it than pure water does.
Category: Bronsted-Lowry Acids and Bases
Question 2
The equilibrium constant for the autoionization of water is symbolized Kw.
Missing Word
Kw
Kw, the ion-product constant of water, equals [H3O+][OH-]. Its value is 1.0 × 10^-14 at 25 °C and increases with temperature.
Category: Bronsted-Lowry Acids and Bases
Question 3
When ammonia acts as a base, it gains a proton and becomes the ammonium ion.
Missing Word
ammonium
The ammonium ion, NH4+, is the conjugate acid of ammonia. It is a weak acid that can donate its extra proton back to a base.
Category: Bronsted-Lowry Acids and Bases
Question 4
A solution in which [H3O+] equals [OH-] is described as neutral at any temperature.
Missing Word
neutral
Neutral means the two ions are present in equal amounts. At 25 °C that corresponds to pH 7, but at other temperatures Kw changes, so a neutral solution can have a pH other than 7.
Category: pH and pOH
Question 5
At 25 °C, a solution with a pOH of 11 is classified as acidic.
Missing Word
acidic
A pOH of 11 corresponds to a pH of 14 − 11 = 3, which is below 7. At 25 °C, solutions with pH below 7 have more H3O+ than OH-.
Category: pH and pOH
Question 6
A weak acid such as phenolphthalein, whose two forms have different colors, is added to the flask to act as an indicator.
Missing Word
indicator
An indicator is a weak acid or base whose acid and base forms differ in color, so the solution changes color over a narrow pH range. One is chosen whose color change falls near the equivalence point.
Category: Titrations
Question 7
The strong acid with the formula HClO4 is perchloric acid.
Missing Word
perchloric
Perchloric acid, HClO4, is one of the common strong acids along with HCl, HBr, HI, HNO3 and H2SO4. It ionizes completely in water.
Category: Acid and Base Strength
Question 8
Strong bases such as NaOH and KOH dissociate completely in water, releasing hydroxide ions.
Missing Word
hydroxide
Hydroxide, OH-, is the ion released by soluble metal hydroxides. Because these compounds dissociate completely, [OH-] equals the concentration of the base times the number of OH- per formula unit.
Category: Acid and Base Strength
Question 9
The equilibrium constant for a weak base reacting with water to form OH- and the conjugate acid of the base is symbolized Kb.
Missing Word
Kb
Kb, the base ionization constant, measures the strength of a base in water. For a conjugate pair, Kb equals Kw divided by Ka of the conjugate acid.
Category: Acid and Base Strength
Question 10
The negative base-10 logarithm of an acid ionization constant is written pKa.
Missing Word
pKa
pKa = −log Ka. A smaller pKa means a larger Ka and therefore a stronger acid.
Category: Acid and Base Strength
Question 11
The reaction of an ion with water that produces H3O+ or OH-, such as acetate ion forming acetic acid and OH-, is called hydrolysis.
Missing Word
hydrolysis
Hydrolysis of a salt's ions explains why many salt solutions are not neutral: anions of weak acids make solutions basic, and cations such as NH4+ make them acidic.
Category: Hydrolysis of Salts
Question 12
An ionic compound made of the cation of a base and the anion of an acid, such as sodium chloride, is called a salt.
Missing Word
salt
A salt forms when an acid reacts with a base. Whether its solution is acidic, basic or neutral depends on whether its ions react with water.
Category: Hydrolysis of Salts
Question 13
The buffer system that helps keep blood pH near 7.4 is based on carbonic acid and bicarbonate ion.
Missing Word
carbonic
Carbonic acid, H2CO3, and its conjugate base, HCO3-, neutralize added base and added acid in blood, holding the pH in a narrow range.
Category: Buffers
Question 14
The reaction of an acid with a base that produces water is called neutralization.
Missing Word
neutralization
In neutralization, H3O+ from the acid and OH- from the base combine to form water, which is the reaction carried out in an acid-base titration.
Category: Titrations
Question 15
Adding a solution of known concentration to a sample until the reaction between them is just complete, in order to find the sample's concentration, is called a titration.
Missing Word
titration
A titration measures the volume of a reagent of known concentration needed to react completely with a sample. That volume and the balanced equation give the unknown concentration of the sample.
Category: Titrations