help please Consider the neutralization reaction below. NaOH(aq) +HF(aq) rightar

Question

help please

Consider the neutralization reaction below. NaOH(aq) +HF(aq) rightarrow H2O (I) + NaF(aq) If equal molar amounts of NaOH and HF are mixed together, Is the resulting solution acidic, basic or neutral? HF is a weak acid, Ka = 3.5 times 10-4 and NaOH Is a strong base. Explain your answer? What is the numerical value of Kb for the conjugate base of HF? If 0 50 moles of NaOH were mixed with 1.0 mole of HF in a 10 L solution, would the resulting solution be a buffer solution? Explain your answer. Determine the pH of the solution in part (c).

Explanation / Answer

Ka=3.5*10^-4

or pKa=3.456

a)when equal molar amount of HF and NaOH are mixed together,

a buffer solution is formed whose pH is given by

pH=pKa+log(salt/acid)

=pKa (since salt/acid=1 and log(1)=0)

so pH=3.456

so the solution is acidic.

b)Ka=3.5*10^-4

Ka*Kb=10^-14

or Kb=2.857*10^-11

c)yes the resulting solution would be a buffer solution,

since NaOH and HF react according to the following equation

HF+ NaOH ---> NaF+ H2O

so moles of NaOH=0.5

so moles og NaF=0.5

so moles of HF left=1-0.5

=0.5

since the solution has a weak acid and it;s salt, it is a buffer solution

d) pH=pKa+log(salt/acid)

=3.456+log(1)

=3.456

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