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
Answer:
ΔH=15000
J = 15KJ
Explanation:
In this exercise you have find the enthalpy of reaction this is the difference between enthalpy of reactans and products,
For the following equation
H2A(aq) + 2 BOH(aq) → B2A(aq) + 2 H2O(l)
We know that 0.20 moles of BOH reacted with excess amount of H2A solution and 1500. J
so,
(2mol/0,2mol)*1500J=15000J
for de reactions exothermics tha enthalpy is negative so:
ΔH=15000
J = 15KJ
Answer:
0.185moles of Al₂O₃
Explanation:
Mass of Al = 10g
Mass of O₂ = 19g
Equation of the reaction: 4Al + 3O₂ → 2Al₂O₃
This is the balanced reaction equation.
Solution
From the given parameters, the reactant that would determine the extent of the reaction is Aluminium. It is called the limiting reagent. Oxygen is in excess and it is in an unlimited supply.
Working from the known mass to the unknown, we simply solve for the number of moles of Al using the mass given.
Then from the equation, we can relate the number of moles of Al to that of Al₂O₃ produced:
Number of moles of Al = 
= 
= 0.37mol
From the equation:
4 moles of Al produced 2 moles of Al₂O₃
0.37 mole will yield: 
= 0.185moles of Al₂O₃
Answer :
1)
Balanced Molecular equation -
KHCO₃ + HC₂H₃O₂ → KC₂H₃O₂ + CO₂ + H₂O
(Potassium bicarbonate) + ( acetic acid)
2)
K⁺ + HCO⁻₃ + HC₂H₃O₂ → K⁺ + C₂H₃O⁻₂ + CO₂ + H₂O
3)
As we knw that the spectator ion are that ion which comes at both sides of the equation,
Here we can see that K⁺ ion comes both side of the equation
So, we get
K⁺ is the spectator ions.
Net ionic equation -
HCO⁻₃ + HC₂H₃O₂ → C₂H₃O⁻₂ + CO₂ + H₂O
The answer is C. The specific amount of energy emitted when electrons jump from excited states to the ground state refers to emission spectrum. The energy is emitted in the form of photons, and the photons have very specific wavelengths (energy) that correspond to the energy gaps between the excited states and the ground state. The specific wavelengths of light emitted are referred to as the "emission spectrum," and each element produces a different emission spectrum. Thus, this emitted energy can be used to identify the element from which your sample was taken.
