Acids and bases Flashcards
(21 cards)
What is a bronset lowry acid
Proton donor (AciD)
What is a bronsted lowry base
Proton acceptor (bAse)
KOH + HCOOH -> HCOOK +H2O which is the bronsted lowry base and acid
Acid-HCOOH base- KOH
Definition of pH
-log [H+]
What would the pH be if the H+ was 0.001?
-log0.001= 3
What would the H+ be if the pH was 2.75
10^-2.75= 1.78x10-3
pH of 0.3 moles of H2SO4
2x0.3= 0.6
-log0.6= 0.22
Calculate the pH of a solution when 100cm3 of water is added to 50cm3 of 0.1moldm HNO3 (dilution)
0.1 x old vol/ new vol
0.1 x 50/150= 0.0333
-log 0.0333= 1.48
Calculating H+ im dilutions
Conc x old vol/ new vol
Whats the equation for the ionic product of water
Kw= [H+] [OH-]
Effect of temperature on pH
If temp increases, equilibrium shifts to the right to oppose change in temp. More H+ and OH- produced, so Kw increases so pH decreases
State why pure water is not acidic at higher temps
H+=OH-
Calculating pure water
Kw=[H+]^2
Or
H+= square root of Kw
Calculate pH of 0.2 moldm of NaOH
Kw= [H+] [OH-] rearrange for H+
H+= Kw/OH-
10^-14/0.2= 5 x10^-14
-log ans= 13.30
Whats the value for Kw
10^-14
Calculate KOH with pH 12.70
10^-12.70= 2x10^-13
OH- = Kw/H+ = 10^-14 / 2x10^-13= 0.05
Calculate pH pf solution formed when 50cm3 of water is added to 100cm3 of 0.2 NaOH (diltuion)
0.2 x 100/150= 0.1333
H+= Kw / OH-
H+= 10^-14 / 0.133= 7.5 x 10^-14
-log ans= 13.12
calculate ph of addition of 25cm of water to 100cm of 0.1 moldm BaOH2
0.1x2=0.2 0.2x100/125=0.16
10-14/0.16=6.25x10-14
-logans=13.20
ph mixtures of strong acids and strong bases
- calculate h+ and oh- moles
- wor out excess (biggest take away smallest)
- calculate concentration of XS (moles/volume)
- wrk out ph
calculate ph of solution when 50cm of 0.100moldm h2so4 is added to 25cm of 0.150dm NaOH
- moles of H2SO4= 2x 50/1000 x 0.1= 0.010
- moles of NaOH = 25/1000 x 0.15= 0.00375
- XS H+ = 0.01-0.00375=0.00625
- conc of H+ = 0.00625/75/1000=0.083
- ph = -logans=1.08
