When the titration of HCN with NaOH is:
HCN (aq) + OH- (aq) → CN-(aq) + H2O(l)
So we can see that the molar ratio between HCN: OH-: CN- is 1:1 :1
we need to get number of mmol of HCN = molarity * volume
= 0.2 mmol / mL* 10 mL = 2 mmol
so the number of mmol of NaOH = 2 mmol according to the molar ratio
so, the volume of NaOH = moles/molarity
= 2 mmol / 0.0998mL
= 20 mL
and according to the molar ratio so, moles of CN- = 2 mmol
∴the molarity of CN- = moles / total volume
= 2 mmol / (10mL + 20mL ) = 0.0662 M
when we have the value of PKa = 9.31 and we need to get Pkb
so, Pkb= 14 - Pka
= 14 - 9.31 = 4.69
when Pkb = -㏒Kb
4.69 = -㏒ Kb
∴ Kb = 2 x 10^-5
and when the dissociation reaction of CN- is:
CN-(aq) + H2O(l) ↔ HCN(aq) + OH- (aq)
by using the ICE table:
∴ the initials concentration are:
[CN-] = 0.0662 M
and [HCN] = [OH]- = 0 M
and the equilibrium concentrations are:
[CN-] = (0.0662- X)
[HCN] = [OH-]= X
when Kb expression = [HCN][OH-] /[CN-]
by substitution:
2 x 10^-5 = X^2 / (0.0662 - X)
X = 0.00114
∴[OH-] = X = 0.00114
when POH = -㏒[OH]
= -㏒ 0.00114
POH = 2.94
∴PH = 14 - 2.94 = 11.06
C5H12 + 8 O2 → 5 CO2 + 6 H2O
8 molecules of O2 are required.
The equation of the chemical reaction is NaHCO3 + H+ --> H2O + CO2 + Na
To determine the total number of moles of carbon dioxide, the given mass of sodium hydrogen carbonate is divided with its own molar mass. Then it is multiplied with the ratio between NaHCO3 and carbon dioxide. The total number of moles of CO2 one tablet should yield is 0.024 mole.
<span>Alkanes are unreactive except in combustion reactions.</span>
In order to see which species has the strongest dispersion forces, you need to calculate their molar mass, because the higher the molar mass, the stronger the dispersion forces.
Since E. C8H18 has the highest molar mass, its dispersion forces are also the strongest ones.
