Answer:
Explanation:
ka is defined as the dissociation constant of an acid. It is defined as the ratio of concentration of products to the concentration of reactants.
For the dissociation of weak acid, the chemical equation follows:
The equilibrium constant is defined by the equilibrium concentration of products over reactants:
Answer: The net ionic equation for the cobalt-silver voltaic cell is
Explanation: In cobalt-silver voltaic cell, one half of the cell consists of cobalt electrode immersed in solution ( which means that
are present in the solution) and other half of the cell consists of the Ag electrode immersed in
solution ( which means that
is present in the solution)
The two electrodes are joined by the copper wire. The cobalt electrode acts as an anode and the silver electrode acts a cathode.
At anode, oxidation reaction takes place and at cathode, reduction reaction takes place.
At Anode :
At Cathode:
Net ionic equation:
Answer:-
Solution:- As is clear from the given Ka value, Cinnamic acid is a weak acid. let's calculate the moles of acid and KOH added to it from their given molarities and mL.
For KOH,
= 0.002 mol
For Cinnamic acid,
= 0.003 mol
Acid and base react as:
The reaction takes place in 1:1 mol ratio. Since the moles of acid are in excess, the acid is still remaining when all the kOH is used.
0.002 moles of KOH react with 0.002 moles of Cinnamic acid to form 0.002 moles of potassium cinnamate. Excess moles of Cinnamic acid = 0.003 - 0.002 = 0.001
As the solution have weak acid and it's salt(or we could say conjugate base), it is a buffer solution and the pH of the buffer solution could easily be calculated using Handerson equation:
pKa could be caluted from given Ka value using the formula:
pKa = - log Ka
pKa = 4.44
let's plug in the values in Handerson equation and calculate the pH:
pH = 4.44+0.30
pH = 4.74
So, the first choice is correct, pH is 4.74.