Acids Arrhenius acids

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)... 

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... 

The conclusion that the nitration of quinoline in sulphuric acid takes place via the conjugate acid has been confirmed by Moodie et al.50, who measured the rates of nitration of a wide range of heterocyclic compounds in nitric acid-sulphuric acid mixtures at a range of temperatures. A summary of the second-order rate coefficients and Arrhenius parameters is given in Table 4. From an analysis of the shapes of the plots of log k2 versus sulphuric acid acidity (or some function of this), it was concluded that all of the compounds starred in Table 4... 

Arrhenius parameters for nitration of 4-aikylphenyltrimethyiammonium ions in nitric acid-sulphuric acid mixtures (Table 12). It was argued that the observed Baker-Nathan order of alkyl substituent effect was, in fact, the result of a steric effect superimposed upon an inductive order. However, a number of assumptions were involved in this deduction, and these render the conclusion less reliable than one would like it would be useful to have the thermodynamic parameters for nitration of the methyl substituted compound in particular, in order to compare with the data for the /-butyl compound, though experimental difficulties may preclude this. It would not be surprising if a true Baker-Nathan order were observed because it is observed for all other electrophilic substitutions in this medium1. 

These compounds are called Arrhenius acids and bases. For instance, HCI is an Arrhenius acid, because it releases a hydrogen ion, H+ (a proton), when it dissolves... 

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 acid A compound that contains hydrogen and releases hydrogen ions (H+) in water. Examples HC1 CH5COOH but not CH4. 

Thus, acids and bases are defined as aqueous solutions of substances and not as the substances themselves. It follows that ionization is a necessary characteristic of Arrhenius acids and bases. Another restriction of this definition is that acid-base behaviour is not recognized in non-aqueous solution. 

Our goal in this chapter is to help you understand the equilibrium systems involving acids and bases. If you don t recall the Arrhenius acid-base theory, refer to Chapter 4 on Aqueous Solutions. You will learn a couple of other acid-base theories, the concept of pH, and will apply those basic equilibrium techniques we covered in Chapter 14 to acid-base systems. In addition, you will need to be familiar with the log and 10 functions of your calculator. And, as usual, in order to do well you must Practice, Practice, Practice. 

All Brpnsted-Lowry and Arrhenius acids contain hydrogen. The formation or transfer of hydrogen ions is the key to the behavior of all acids. You may wish to review the behavior of acids in Chapters 4 and 15. 

An acid is a substance that dissociates in water to form H q). Two examples of Arrhenius acids are hydrochloric acid, HCl, and sulfuric acid, H2SO4. 

H (aq) Cl (aq) hJa (aq) + OH (aq) Fla (aq) "t" Cl (aq) "t" H20(r) AH = —56 kJ Subtracting spectator ions from both sides, the net ionic equation is H+(aq) -I- OH (aq) H20(f) AH = -56 kJ Different combinations of strong Arrhenius acids and bases react with the same exothermic result. Measurements always show the release of 56 kJ of energy per mole of water formed. This makes sense, because the net ionic equation is the same regardless of the specific neutralization reaction that occurs. 

S. A. Arrhenius defined an acid as any hydrogen-containing species able to release protons and a base as any species able to form hydroxide ions [71]. The aqueous acid-base reaction is the reaction between hydrogen ions and hydroxide ions with water formation. The ions accompanying the hydrogen and hydroxide ions form a salt, so the overall Arrhenius acid-base reaction can be written ... 

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. 

The above reaction depicts water as an Arrhenius acid and base. Treating water in terms of the Bronsted-Lowry theory, a more appropriate reaction would be... 

For Arrhenius acids, remember to track the movement of H" and OH ions. If the reaction yields an OH product, the substance is a base, whereas an H+ product reveals that the substance is an acid. 

In 1884, Swedish chemist Svante Arrhenius defined acids as compounds that produce H" " ions in aqueous solutions, and bases as compounds that produce OH ions in aqueous solutions. For example, HCl and HNO3 are Arrhenius acids. 

The Arrhenius acid-base theory is insufficient to explain the acidic or basic properties of some substances, such as SO2 and NH3, since these don t have H" and OH ions in their structures. For these molecules, another theory must be applied, since the Arrhenius acid-base theory can only be applied to aqueous solutions. 

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-... 

Antiferromagnetism, 467-468 Aprotic solvents, 369-373 Aqueous solvents, and non-aqueous solvents. 359-386 Arachno structures, 798-800, 807 Aragonite, 98, 953 Arene complexes, 681-683 Arrhenius acid-base definition, 319... 

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 ... 

Thus far we ve been using the Arrhenius theory of acids and bases (Section 4.5). According to Arrhenius, acids are substances that dissociate in water to produce hydrogen ions (H + ), and bases are substances that dissociate in water to yield hydroxide ions (OH-). Thus, HC1 and H2SO4 are acids, and NaOH and Ba(OH)o are bases. 

---