8.1
Acid ▪ increases hydronium ions when dissolved in water
▪ tastes sour
▪ many acids start with “H”
Hydronium Ion ▪ H3O+1
Base ▪ increases hydroxide ions when dissolved in water
▪ tastes bitter
▪ many bases end with “OH”
Hydroxide Ion ▪ OH-
Ionize ▪ to form ions
Strong Acids/Bases ▪ completely ionize
Weak Acids/Bases ▪ do not ionize completely
Indicator ▪ a substance that changes color in response to pH changes in a solution
▪ ex: litmus paper, cabbage juice, phenolphthalein
Electrolyte ▪ a solution that can conduct electricity
▪ this is due to the many dissolved ions
▪ strong acids and bases are strong electrolytes
▪ weak acids and bases are weak electrolytes
▪ salt water is a good electrolyte because it forms many ions in solution
Dangerous? ▪ acids or bases can both be dangerous when in high concentrations
What is pH?
pH ▪ a measure of the concentration of
hydronium ions
▪ used to express how acidic or basic a solution is
pH Scale ▪ 0 – 14 (typically!)
▪ 0=very acidic
▪ 14=very basic (alkaline)
▪ 7=neutral
▪ based on powers of ten
▪ if the pH lowers by 1, the acidity is 10 times as great
▪ if the if the pH lowers by 4, the acidity is 10,000 times as great
8.2
Acid-Base Reactions
Neutralization ▪ a reaction between an acid and a base producing salt and water
HCl + NaOH --> NaCl + H2O
HNO3 + KOH --> KNO3 + H2O
Salts ▪ Not just NaCl!
▪ Forms from the positive ion of a base and the negative ion of an acid in a neutralization reaction
Water ▪ Forms from the H3O+ ion from the acid and the OH- ion from the base
Titration ▪ the process of gradually combining an acid and a base in the presence of an indicator to determine the concentration of one of the solutions
▪ titrations are neutralization reactions (even though the product is not always “neutral”)
8.3
Acid-Base Reactions
Soap combination of salts and fatty acids
(+) ions soluble in water, (-) ions soluble in oil…this allows the soap to suspend or emulsify oil droplets which can be easily rinsed away
not useful in hard water à soap scum
Detergent similar to soap, except made from different ions do not form soap scum
Disinfectant substance that kills bacteria
Bleach a basic solution that is a disinfectant
Antacid a weak base that neutralizes stomach acid
Equivalence
Point when the amount of acid in a solution is equal to the amount of base
pH does not necessarily = 7
ex: weak acid + strong base…
pH > 7