6. "A neutral solution always has a pH equal to 7."
The percent of water molecules that ionizes depends a great deal on temperature. Only at
25 ^oC does [H⁺] x [OH^-] = 10^-14, giving a pH of 7 at neutrality. As temperature increases so does the percent of water molecules that ionize. Thus, at higher temperatures the pH of neutrality decreases. At body temperature, 37 deg.C, the pH of neutral water is 6.81.

7. "A neutralization reaction produces a neutral solution."
A neutralization reaction is one in which acid and base properties disappear when an acid solution is added to a base solution. An ionic compound (a salt) results. The ionic compound may or may not be a neutral compound. See the Hydrolysis section under Extensions.

8. "A pH = 0 means that no acid or base is present."
A solution with a pH = 0 would be very acidic--in fact, the solution would have a hydrogen ion concentration of 1 M. (pH = -log(1) = 0)

9. "The compound HNaO would be considered an acid."
Students often think that the way a compound's formula is written determines whether the compound is an acid or a base. Because of the way that Na, O, and H interact, they produce a compound commonly known as sodium hydroxide. No matter how we write the formula (HNaO or NaOH), the same basic compound is produced. A similar confusion can arise when acetic acid is written as HC2H3O2 or CH3COOH. In both cases an acidic compound is represented. The difference is that the first is written to correspond to the way most mineral acids are written, while the second gives a better indication of its actual organic carboxylic structure. It's not how we write the formulas, but how the atoms in the structure actually interact that determines the properties of compounds.

10. "The end point and neutralization point in a titration are the same."
>Not so--neutralization involves consuming all acid and base; end point depends on indicator color change.

11. "A concentrated acid is a pure substance."
Acids are usually used in aqueous solutions and are mixtures, not pure substances.

12. "Concentrated acids are much more dangerous than concentrated bases."
Most beginning chemistry students have some knowledge of the dangers of concentrated acids. (Battery acid, horror movies,etc) These same students have little or no knowledge of bases and their properties. Students should be reminded that most "bowl cleaners" are concentrated bases because they are good at dissolving organic material. When students realize they are made up of organic material, they begin to build a healthy respect for bases.

13. "Only pH values of 1-14 exist."
The definition of pH(-log H+) permits values outside the 1-14 range, although they are seldom encountered. Substituting molarity of commercial concentrated hydrochloric acid (12M) in the definition equation gives a pH = -1.1; for 18 M sulfuric acid, the pH = -1.3. Similarly, the 8 M sodium hydroxide solution used to make soap from animal fat has a pH = 14.9.

Solutions of such extreme concentrations are seldom used, except as concentrates for making the dilute solutions of 1-14.

14. " For sulfuric acid, to say that dissociation is complete means the acid has lost both protons."
When we say that dissociation of sulfuric acid is complete, we are not saying that the species in solution are two hydrogen ions and one sulfate ion for each molecule dissolved. The fact is, sulfuric acid is "strong" only in regard to removal of the first hydrogen ion.

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