Answer:
0.084 M
Explanation:
Using the Henderson-Hasselbalch equation for a buffer ( a buffer is solution contain a weak acid and it conjugate base; the solution resist change in pH)
pH = pKa + log ( base/acid)
4.9 - 4.76 =log ( base / acid)
10^0.14 = ( base / acid)
1.38 = (base / acid)
since there is 0.2 M in the buffer solution
the concentration of acid = 
× 0.2 = 0.084 M
Answer:
Here, we are required to determine the total energy of the reaction and determine if the reaction is an endothermic or exothermic reaction.
The correct answer is option C.
First, we need to determine the energy of the reaction.
The energy of the reaction is the change in enthalpy between the product and reactants.
Change of Enthalpy,
Hreaction = Hproduct - Hreactant.
Therefore, for the reaction above, the change in enthalpy is:
Hreaction = 590kJ/mol - 581kJ/mol.
Hreaction = 9kJ/mol.
Hence, since the reaction has an enthalpy change of 9kJ/mol, the reaction is endothermic (i.e energy is absorbed).
Explanation:
