acids and bases Flashcards

1
Q

define an acid

A

Bronsted Lowry definition of an acid is a species that donates a proton, H+, during an acid-base reaction

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2
Q

common acids

A

hydrochloric acid HCl
sulfuric acid H2SO4
nitric acid HNO3
phosphoric acid H3PO4
ethanoic acid CH3COOH
carbonic acid H2CO3
ammonium NH4+

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3
Q

acids change indicators?

A

blue litmus -> red
phenolpthalein -> colourless
methyl orange -> red

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4
Q

general properties of acids

A

-tend to be corrosive
-taste sour
-react with bases
-have a pH less than 7
-solutions can conduct an electric current

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5
Q

define a base

A

Bronsted Lowry definition of a base is a species that accepts a proton, H+, during an acid-base reaction

an alkali is a soluble base that dissociates hydroxide ions

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6
Q

bases change indicators?

A

phenolpthalein -> pink
methyl orange -> yellow
red litmus -> blue

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7
Q

general properties of bases

A

-have a slippery feel
-taste bitter
-are caustic
-react with acids
-have a pH above 7 (alkalis only)
-solutions can conduct an electric current

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8
Q

define ionisation

A

the process by which a chemical species gains or loses an electric charge

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9
Q

define dissociation

A

the process by which a molecule separates into smaller particles

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10
Q

common bases

A

sodium hydroxide NaOH
ammonia NH3
magnesium hydroxide Mg(OH)2
potassium hydroxide KOH
oxide O2-
calcium hydroxide Ca(OH)2

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11
Q

conjugates

A

acid and conjugate base = pair
this is where the acid, has donated a proton and thus the conjugate base has hydrogen less eg. H2O -> OH-

base and conjugate acid = pair
this is where the base, has accepted a proton and thus the conjugate acid has more hydrogen eg. H2O -> H3O+

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12
Q

what are amphiprotic species?

A

amphiprotic species can either donate or accept a proton, H+
these substances have the availability to accept or donate a proton eg. water

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13
Q

ionic equations

A

these are simplified equations that do NOT include any spectator ions (aqueous ions which do not react and remain dissolved in solution throughout a reaction)

eg. 2K(s) + 2H+(aq) -> 2K+ (aq) +H2 (g)

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14
Q

strength of acids or bases?

A

related to how willingly it will donate or accept a proton

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15
Q

strong acid?

A

one that will undergo complete ionisation when added to water, almost all acid molecules in the solution will donate proton to form aqueous H+ ions

three common = sulfuric acid, hydrochloric acid, nitric acid

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16
Q

weak acids?

A

does not readily give up its H+ ions in a solution
use the double harpoon to show that these reactions do not go to completion

three common = ammonium, ethanoic acid, carbonic acid

17
Q

strong bases?

A

readily accept a proton during an acid base reaction, one that completely dissociates to form hydroxide ions, OH-, and a basic equation

eg. NaOH, KOH, Ca(OH)2

18
Q

weak bases?/

A

does not readily accept H+ ions
use double harpoon to show reactions do not go to completion

eg. ammonia, sulfate, ethanoate, bicarbonate, fluoride

19
Q

strength of conjugate pairs?

A

strong acids have negligible conjugate bases
strong bases have negligible conjugate acids

20
Q

strength vs concentration

A

the strength of an acid relates to what proportion of its molecules will donate a proton, H+
whereas an acids concentration depends on how many of those acid molecules were in the solution to begin with

21
Q

pH scale

A

the stronger the acid, the lower the pH value
neutral solutions have a pH of 7
the stronger the base, the higher the pH value

22
Q

formula to find pH

A

pH = -log[H3O+]

23
Q

ionic product of water

A

[H+] x [OH-] = 10-14 M

24
Q

finding concentration from pH

A

[H3O+] = 10^-ph

25
Q

pH of basic solution

A

pH = 14 + log[OH-]

26
Q

equation of weak acid’s reaction with water

A

HA (aq) + H20 (l) <-> H30+ (aq) + A- (aq)

27
Q

equilibrium constant expression?

A

[H30+] [A-] // [HA] [H20]

28
Q

acid dissociation constant?

A

Ka - this is the equilibrium constant for the dissociation of an acid in aqueous solution. it tells us how far the reaction has proceeded towards completion before equilibrium is established

Ka = [H30+] [A-] // [HA]

29
Q

Ka - simple formula

A

Ka = [H+]^2 // [HA]
knowing the concentration of H3O+ is equal to the conc. of H+

30
Q

acids and conductivity

A

not all acids of conc 0.1M have the same pH, and do not conduct electricity to the same extent
conductivity of a solution = directly related to the number of ions in a solution

31
Q

what happens when an acid is diluted?

A

the concentration of H+ ions decreases and the pH increases towards 7