chapter 8: acid and bases Flashcards
define acids
substance that dissociates in water to form hydrogen ions
who is responsible for acid properties?
H+ ions
what is basicity?
number of H+ ions per molecule formed when it dissociates in water
or
maximum no. of H+ ions that can be produced
mono - produces 1 mol of H+ ions per molecule (e.g HCl)
di - 2 “ (e.g. H2 SO4)
tri - 3 “
what are the acid properties?
- PSCMAZITL metals displace H+ ions from acid to form hydrogen gas
- if a product is an insoluble salt, a coating is formed around the reactant to prevent further reaction with acid. (reaction stops prematurely -> acid cannot react w reactant)
what are the 3 acid reactions?
- base + acid -> salt + water (neutralisation)
- metal + acid -> salt + hydrogen
- carbonate + acid -> salt + water + carbon dioxide
what is the difference between strong and weak acids?
strong:
- completely dissociates
- produces high conc of H+ ions
e.g. HCL, H2SO4, HNO3
weak:
- partially dissociates
- produces low conc of H+ ions
e.g. the rest
what is the difference between strength and conc?
strength:
- extent of dissociation
concentration:
- no. of acid molecules present
define base
any metal hydroxide / oxide that reacts with acids to produce salt and water
define alkali
soluble bases which produce OH - ions in water
what are the properties of alkalis?
- reacts with ammonium salts
-> alkali + ammonium salt -> salt + water + ammonia (gas)
what’s the pH curve of ‘strong acid + strong base’?
pH = 7
normal graph
what’s the pH curve of ‘strong acid + weak base’?
pH < 7
what’s the pH curve of ‘weak acid + strong base’?
pH > 7
what’s the pH curve of ‘weak acid + weak base’?
pH = 7
lazy looking graph
how to control the pH of soil?
add calcium hydroxide
- remains solid if no acid present
- reacts with acid
