reactivity 3.1 Flashcards
equation for calculating pH
– log₁₀[H⁺]
equation for calculating [H⁺]
10⁻ᴾᴴ
what defines an arrhenius acid?
a substance that disassociates in water to form hydrogen ions (H+) and anions
what defines an arrhenius base?
a substance that disassociates in water to form hydroxide ions (OH-) and cations
what does the bronsted-lowry theory focus on?
the transfer of H+ ions during an acid-base reaction (acids donate H+ while bases accept H+)
what is a bronsted-lowry acid?
a proton donor
what is a bronsted-lowry base?
a proton acceptor
define alkali
soluble bases which dissolve in water to release OH-
define amphiprotic
substances that can act as both bronsted-lowry acids and bases
requirement for a substance to be amphiprotic
must posses both a lone pair of electrons and hydrogen that can be released as H+
moving left to right across a period, oxides transition from ______ ______ oxides through ______ oxides then to ______ oxides
basic metal
amphiprotic
acidic
basic metal oxides react with an acid to form what?
a salt and water
non-metal oxides form ______ ______ in a solution
weak acids
amphiprotic oxides react with either an acid or a base to form what?
a salt and water
the burning of fossil fuels releases what 3 substances
GHG, nitrous oxides ans sulfuric oxides
what causes acid rain
increased emissions of nitrous oxides ans sulfuric oxides in the atmosphere, which turn rain water from its slightly acidic state (pH = 6) to become a stronger acid
where is acid rain’s negative effects seen? x3
structural materials, lakes/rivers & plant life/forests
what pH is acid rain?
pH = <5.6
what is the [H+] range (in numerical values) for the 0-14 pH scale?
1.0mol dm^-3 →10^-14 mol dm^-3
increasing pH by 1 = _______ [H+] by __ times
decrease, 10x
decreasing pH by 1 = _______ [H+] by __ times
increase, 10x
if the pH of a solution is changed from 3 to 5, how does the [H+] change?
pH = 3 => 10^-pH = 1 x 10^-3 mol dm^-3
pH = 5 => 10^-pH = 1 x 10^-5 mol dm^-3
[H+ ions] decreases by (1 x 10^-3 mol dm^-3)/(1 x 10^-5 mol dm^-3) = 100x times
what is the relationship between [H+] and [OH-]?
higher [H+] = lower [OH-]
lower [H+] = higher [OH-]
in terms of pH, what does a surplus of [H+] signify? what does a surplus of [OH-] signify?
surplus of [H+] = low pH = acidic
surplus of [OH-] = high pH = basic
pH’s neutral value = 7 at what temperature?
298K
how to find [H+] with value of [OH-]?
Kᵥᵥ / [OH-]
how to find [OH-] with value of [H+]?
Kᵥᵥ / [H+]
pH of pure water goes ____ as temperature goes ____
down, up
despite changes in pH, why is water is still neutral?
[H+] = [OH-]
characteristics of a strong acid x2
dissociates fully
good proton donors
why do strong acids have weak conjugate bases?
because their reactions fo virtually to completion so they are not readily able to accept a proton
characteristics of a weak acid x2
dissociates only partially
poor proton donors
why do weaker acids have strong conjugate bases?
their dissociation reactions are equilibria that lies in favour of reactants, their CB are readily available to accept a proton
acid dissociation reactions favour the production of a _______ conjugate. why?
weaker. better for strong acid to dissociate
characteristics of a strong base x2
ionizes fully
good proton acceptors
characteristics of a weak base x2
ionizes partially
poor proton acceptors
base ionization reactions favours the production of the _____ conjugate
weaker
strength of an acid or base is a measure of what?
how readily it dissociates/ionizes in aqueous solution (similar to solubility) to release H+/OH-
strong acids x5
HCl
HBr
HI
HNO3
H2SO4
strong bases x3
LiOH
NaOH
KOH
weak acids x3
CH3COOH
H2CO3
H4PO4
weak bases x2
NH3
C2H5NH2 (& other amines)
as the halogen atom ______ in size going down group 17, the length of the H-halogen bond ________
increases, increases
are longer bonds weaker or stronger? do they require more or less energy to break?
weaker, less
acid strength of hydrogen halides _______ down the group
decreases
HF < HCl < HBr < HI
electrical conductivity depends on the concentration of what?
mobile ions
greater ionization in solution for strong acids & bases ⟹ _______ concentration of ions ⟹ ________ conductivity than weak acids and bases
(only if solutions of the same concentration are compared)
higher, higher
neutralization reactions x2 products, exo or endo?
salt and water, exo
when acids react with reactive metals, they also form salts as the hydrogen in the acid is replaced by the metal. why is there no transfer of a proton?
the hydrogen is released as H2 gas
when acids react with reactive metals,
electrons as a product = what type of reaction?
electrons as a reactant = what type of reaction?
electrons as a product = oxidation
electrons as a reactant = reduction
when acids react with reactive metals, why is the metal being ionized?
because H+ are becoming electrically neutral by accepting e- while the metal is being ionized by e- loss
acid + carbonate → ___ + ___ + ___
2 examples of carbonates
salt, water, CO2 gas
metal carbonates (CO3^2-) and hydrogencarbonates (HCO3-)
how to determine ionic/net ion equations
break up compounds, cancel out things shown on both sides of the reaction
define effercescence
reactions involving a gas being given off so they visibly produce bubbles
in neutralisation reactions, how is pure salt separated?
filtration followed by evaportation
what is the net ion reaction for reactions between an acid and a base?
H+ (aq) + OH- (aq) → H2O (l)
define spectator ions
other ions which do not change during the reaction and can be cancelled out
why are neutralisation reactions exothermic?
because for every mole of H2O that forms, 2 moles of O-H bonds are made
bond making is exothermic, so overall it is an exothermic reaction
what is the enthalpy of neutralisation reaction between all strong acids and strong bases? how is it expressed?
ΔH = -57 kJ mol^-1
expressed per mole of H2O formed
define monoprotic acid
only has 1 H+ to give
what point is reached when the acid and a base neutralise each other in a titration? x2 names
equivalence point OR stoichiometric point
at the equivalence point of a strong acid and strong base titration, what does the solution contain?
water and salt
how is the reaction ratio of acid to base to reach this point is determined by what?
the stoichiometry of the neutralisation reactions (mole ratios of acid to base reactants)
review last page of r3.1 lesson 04 with volume of added base calculations
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