Arrhenius base

Arrhenius acid Species that, upon addition to water, increases [H+], 86 Arrhenius base Species that, upon addition to water, increases [OH-], 86 Arrhenius equation Equation that expresses the temperature dependence of the rate constant In k2/ki = a(l/Ti — 1 IT2)IR, 302-305... 

Sodium metal, although it produces OH ions when it reacts with water, is not an Arrhenius base, because it is an element, not a compound, as the definition requires. 

Recall that an Arrhenius acid is a compound that produces hydronium ions in water and an Arrhenius base is a compound that produces hydroxide ions in water. 

Arrhenius base (a compound that supplies OH in water)... 

Arrhenius base A compound that produces hydroxide ions (OH ) in water. Examples NaOH NH3 but not Na, because it is not a compound. 

These species are Bronsted-Lowry bases in water (none are Arrhenius bases) since they are proton acceptors and OH" ions are produced NH3, HS, CH3COO and O2. ... 

Arrhenius acid, Bransted-Lowry acid Arrhenius acid, Bransted-Lowry acid Arrhenius base, Bransted-Lowry base Arrhenius acid, Bransted-Lowry acid amphoteric hydroxide (can act as either an acid or base)... 

A base is a substance that dissociates in water to form OH (aq). Two examples of Arrhenius bases are sodium hydroxide, NaOH, and potassium hydroxide, KOH. 

Although many other acid-base definitions have been proposed and have been useful in particular types of reactions, only a few have been widely adopted for general use. Among them are those attributed to Arrhenius (based on hydrogen and hydroxide ion formation), Br0nsted-Lowry (hydrogen ion donors and acceptors), and Lewis (electron pair donors and acceptors) [6,67-70]. 

Arrhenius acid—any substance that ionizes when it dissoives in water to give the H ion. Arrhenius base—any substance that ionizes when it dissoives in water to give the OH" ion. 1 point for correct answer. 

NaOH and Ba(OH)2 are examples of Arrhenius bases. These bases release OH ion in aqueous media. 

Pure water can be considered both an acid and a base because water dissociates slightly to produce hydrogen and hydroxide ions H2Offi < > H+(a(i) + OH (a. This equation depicts water as an Arrhenius acid and base. An Arrhenius acid is any substance which when dissolved in water produces hydrogen ions, H+. An Arrhenius base is a substance that produces hydroxide ions, OH. Treating water in terms of the Brans ted-Lowry theory, a more appropri-... 

We shall call such substances Arrhenius acids and bases. For instance, HC1 is an Arrhenius acid, because it releases a hydrogen ion, H+ (a proton), when it dissolves in water CH4 is not an Arrhenius acid, because it does not release hydrogen ions in water. Sodium hydroxide is an Arrhenius base because OH ions go into solution when it dissolves ... 

Give three examples of molecules or ions that are Bronsted-Lowry bases but not Arrhenius bases. 

A Lewis base transfers an electron pair to a Lewis acid. A Bronsted acid transfers a proton to a Bnansted base. These exist in conjugate pairs at equilibrium. In an Arrhenius base, the proton acceptor (electron pair donor) is OH-. All Arrhenius acids/bases are Bronsted acids/bases and all Bransted acids/bases are Lewis acids/bases. Each definition contains a subset of the one that comes after it. 

C Choice A is the definition of a strong acid, choice B is the definition of a Lewis acid, and choice D is the definition of an Arrhenius acid. By definition, all Arrhenius bases form OH- ions in water, and all Bronsted bases are proton acceptors. But not all Bronsted bases use OH- as a proton acceptor. NH3 is a Bronsted base for example. 

An Arrhenius base is a substance that, when dissolved in water, increases the concentration of OH- ions in the solution ... 

A Bronsted-Lowry base is a substance that accepts a proton from another substance. This is a significant change from the Arrhenius definition. Arrhenius bases possess an OH, whereas Bronsted-Lowry bases need not. In the example below, notice how ammonia increases the concentration of hydroxide ion in the resulting solution without donating a OH- ion. It does so by accepting a proton from water ... 

Arrhenius acids increase the concentration of H+ ions in solution, while Arrhenius bases increase the concentration of OH- in solution. The strongest acids and bases are Arrhenius acids and bases. 

In addition to Arrhenius acids and bases, the Brpnsted-Lowry definition includes bases that have no hydroxide ions, yet can accept protons. Consider the following examples of acids donating protons to bases. NaOH is a base under either the Arrhenius or Brpnsted-Lowry definition. The other three are Brpnsted-Lowry bases but not Arrhenius bases, because they have no hydroxide ions. 

Bases, on the other hand, increase the concentration of OH in aqueous solutions. An Arrhenius base must contain the hydroxyl group, —OH, as the source of OH-. You can see this in the dissociation reactions for... 

Ammonia does not contain hydroxide ions, so it is not an Arrhenius base. As you can see, however, an ammonia molecule can remove a proton from water, leaving a hydroxide ion behind. Thus, ammonia is a Bronsted-Lowry weak base. 

The following is a short list of some weak bases and their uses. Which ones are Brpnsted-Lowry bases, but not Arrhenius bases ... 

B Arrhenius bases yield hydroxide ions as the negative ions in solution. 

Acid strength determines to what extent an acid reacts with water. All acids react extensively with Arrhenius bases. 

Arrhenius base (8.4) A compound that provides OH ions to water. 

The first person to recognize the essential nature of acids and bases was Svante Arrhenius. Based on his experiments with electrolytes, Arrhenius postulated that acids produce hydrogen ions in aqueous solution, and bases produce hydroxide ions. At the time of its discovery the Arrhenius concept of acids and bases was a major step forward in quantifying acid—base chemistry, but this concept is limited because it applies only to aqueous solutions and allows for only one kind of base—the hydroxide ion. A more general definition of acids and bases was suggested independently by the Danish chemist Johannes N. Bronsted (1879-1947) and the English chemist Thomas M. Lowry (1874-1936) in 1923. In terms of the Bronsted—Lowry definition, an acid is a proton (H+) donor, and a base is a proton acceptor. For example, when gaseous HCl dissolves in water, each HCl molecule donates a proton to a water molecule, and so HCl qualifies as a Bronsted-Lowry acid. The molecule that accepts the proton—water in this case—is a Bronsted-Lowry base. 

The definitions of Arrhenius acid and Arrhenius base given earlier in this book are variants of the definitions of acid and base originally proposed by Arrhenius in the late 19th century. One drawback that the Arrhenius definitions have is that they are limited to aqueous solutions HCl, for instance, should be considered an acid whether it is in the form of a pure gas or in aqueous solution. Another limitation is that the Arrhenius definition cannot classify substances that sometimes act as acids and sometimes act as bases. 

Again, notice that ammonia, a Brpnsted-Lowry base, is also an Arrhenius base. All Arrhenius bases are also Brpnsted-Lowry bases. Ammonia does not have to react in aqueous solution to be considered a Br0nsted-Lowry base. Even as a gas, ammonia accepts a proton from hydrogen chloride, as Figure 8 shows. 

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