acids and bases Flashcards
(28 cards)
what are conjugated bonds
alternating single and double bonds
what does conjugation change
enhances stability, changes structure, different reactivity, changes spectroscopic behaviour (can absorb uv maybe)
relationship between conjugation and wavelength
more conjugation=longer wavelength of light absorbed
why do some polyenes appear coloured
they have many conjugated double bonds so they can absorb light in the visible region of spectrum so they appear coloured
what colour will substances appear if they absorb visible light
the colour will appear as the complementary colour to the one absorbed (colour opposite on colour wheel)
describe the structure of benzene
aromatic and a conjugated molecule, all bonds are same length and are partial double bonds, delocalised pi electrons around/above/below plane
how to tell if a molecule is aromatic
Huckels rule, 4n+1=number of pi electrons, if n is whole number then it is aromatic
what is a arrhenius acid
a substance that increases concentratino of H+ when dissolved in water
what is an arrhenius base
a substance that increases the concentration of OH_ when dissolved in water
what is a arrhenius acid base reaction
an acid reacts with a base to create water and a salt, often called neutralisation
what is a bronsted lowry acid
H+ donor, substance that can donate a hydrogen ion
what is a bronsted lowry base
H+ acceptor, substance that can accept a hydrogen ion
what is a bronsted lowry acid base reaction
transfer of a hydrogen ion
why are arrhenius definitions limited
requires water as a solvent, liquid phase, only depends on two ions (restricted by solvent and phase)
why is the bronsted lowry definitions a broader definition than arrhenius
not solvent restricted, not phase restricted but still restricted by hydrogen ion
example of a bronsted lowry acid base reaction
autoionization of water, water acts as both acid and base
what is a lewis acid
electron pair acceptor, substance that can accept an electron pair
what is a lewis base
electron pair donor, substance that can donate an electron pair
what is a lewis acid base reaction
donation of an electron pair to create a new covalent bond
why is lewis acid base definitions better than bronsted lowry and arrhenius
no solvent or phase restrictions and not dependent on a single chemical species
what is a strong acid
completely transfers hydrogen ion to water in aqueous solution, reaction goes into completion
what is a weak acid
only partially transfers hydrogen ion to water in aqueous solution, reaction goes to equilibrium
examples of some strong acids and bases
any reaction using a strong aid/base will go into completion
acid- HCl, HBr, HNO3, h2SO4
base- group 1 hydroxides, LiOH, NaOH, Mg(OH)2, Ca(OH)2
what is a conjugate acid
the H+ donor written on the products side of the reaction
