Concentrations of Solutions Chapter 10.2 and 10.3 Notes

Strong Acids In general, the stronger the acid, the more readily it donates a positive charge, usually a hydrogen ion If water is added to an acid and almost all of the acid is converted to the hydronium ion, H 3 O +, then it is a strong acid There are 7 strong acids Hydrochloric acid, HCl Hydrobromic acid, HBr Hydroiodic acid, H I Nitric acid, HNO 3 Chloric acid, HClO 3 Sulfuric acid, H 2 SO 4 Perchloric acid, HClO 4

Weak Acids When water is added to a weak acid, a lot of the acid will still be present Weaker acids have a lesser tendency to donate hydrogens to water, therefore the acid remains and hydronium ions are not formed When weak acids are dissolved in water, there are only a very few ions, so there is not much of an electrical current In contrast, when a strong acid is dissolved in water, there are many ions formed, so there is a large electrical current

Strong Bases The stronger the base, the more readily it accepts a positive charge, usually a hydrogen ion Strong bases allow the flow of a large electrical current There are 8 strong bases: Lithium hydroxide, LiOH Sodium hydroxide, NaOH Potassium hydroxide, KOH Rubidium hydroxide, RbOH Cesium hydroxide, CsOH Calcium hydroxide, Ca(OH) 2 Strontium hydroxide, Sr(OH) 2 Barium hydroxide, Ba(OH) 2

Weak Bases Do not readily accept a hydrogen ion Do not allow a large flow of electrical current Ammonia, NH 3, and water are common weak bases Concentration is the most important factor in determining if strong/weak acids/bases are dangerous Very concentrated ammonia can burn you even though it is a weak base Very dilute hydrochloric acid won’t be as threatening as if it were a concentrated solution

Amphoteric Solutions A substance that is just as likely to behave as an acid as it is to behave as a base is said to be amphoteric Water is amphoteric because it has the ability to react with itself As an acid, water molecules will donate hydrogens to neighboring water molecules, which in accepting the hydrogen ion is acting as a base The reaction forms a hydronium ion and a hydroxide ion, which react together to re-form water

Neutral Solutions In a neutral solution, the amount of hydronium ions is equal to the amount of hydroxide ions Pure water is an example of a neutral solution In pure water, the concentration of hydronium ions is equal to 1x10 -7, and the concentration of hydroxide ions is equal to 1x10 -7 “concentration of hydronium ions” can be written as: [H 3 O + ] “concentration of hydroxide ions” can be written as: [OH - ]

Acidic Solutions In an acidic solution, the hydronium ion concentration is greater than the hydroxide ion concentration [H 3 O + ] > [OH - ] Acidic solutions are made by adding acid to water—always add acid to water, never add water to acid, doing so will cause the water to boil very quickly and will spray hot acid

Basic Solutions In a basic solution, the hydroxide ion concentration is greater than the hydronium ion concentration [OH - ] > [H 3 O + ] A basic solution is made by adding a base to water

Classwork Page 354 # 8—14