acid and base Flashcards
(44 cards)
what are the general characteristics of an acid
they have a sour taste, they’re liquid and react with bases
what are the general characteristics of a base
they have a bitter taste, they’re solid, react with acids and they feel soapy
what did Arrhenius model 1884 suggest about acids and bases
suggested that when acids dissolve in water they release H+ ions and that when bases dissolve in water they release OH- ions
what happens when an acid (eg, HCl) goes into water
it dissociates and forms H+ and Cl- ions
what happens when a base (eg, KOH) is added into water
it dissociates and forms K+ and OH- ions
what does aqueous mean
can dissolve in water
what does dissociation mean
when a chemical reaction occurs and the compound breaks into 2 or more substances. (eg, AB= A + B)
what is a neutralisation reaction
when we mix an acid and a base
(eg, HCl + NaOH = H20 + NaCl)
what are the limitations of the Arrhenius model
- ## is it an acid or base eg, NH3 can act as both
what model can be used instead of the Arrhenius model
the Bronsted-Lowry model (1923)
what does the Bronsted-Lowry model suggest
suggests that an acid can donate a proton H+ and a base can accept a proton H+
what does acidity and basicity depend on and not depend on
- depends on chemical species and not substance
- depends on chemical reaction and not chemical formula
describe an acid
an acid can be strong or weak. it can form aqueous solutions with a pH of less than 7. they can ionise meaning they can form ions such as H+
what does pH mean
the conc of H+ ions
describe strong acids
they release lots of H+ ions meaning the ionise (convert into ion) and dissociates (splits into 2 molecules) completely
describe weak acids
they don’t ionise meaning only some H+ ions are released and dissociate completely (only some)
why do weak acids have a forward and backwards arrow in the reactions
because reactants can form products and products can reform reactants. they reach an equilibrium as they don’t completely dissociate.
what does strength mean
this means how much an acid dissociates
what does concentration mean
how much acid there is in a certain volume. the more concentrated a substance is the more acid it contains.
what is the equation to calculate the pH (of an acid)
pH= -log [H+]
what is the equation to calculate the pOH (of a a base)
pOH= -log [OH-]
if your pH is high what does it suggest
that you have lots of H+ ions
if your pH is low what does it suggest
that you have little H+ ions
if your pOH is high what does it suggest
that we have lots of OH- ions
