Buffer solutions?

Question

Which of the following mixtures will result in the formation of a buffer solution if all solutions are 1.0 M before mixing?

i) 100. mL of NH3(aq) and 100. mL of HCl(aq).

ii) 100. mL of NH3(aq) and 50. mL of HCl(aq).

iii) 100. mL of NH3(aq) and 50. mL NaOH(aq).

iv) 100. mL of NH4Cl(aq) and 100. mL of NH3(aq).

v) 100. mL of NH4Cl(aq) and 50. mL of NaOH(aq).

a. ) i and ii

b. ) i and iv

c. ) ii and v

d. ) ii, iii, and v

e. ) ii, iv, and v

Answer 1

a ..i guess

Answer 2

Answer should be E.

We know IV) is correct for sure because a buffer is created with a weak base (NH3) and its conjugate acid (NH4+)

You can do some calculations to make sure II) and V) are correct as well.  Both a strong acid or a strong base may be used to create a buffer if it is not used in large quantities.  Why?  Because adding either one will stimulate the formation of either the conjugate acid or base for NH3 or NH4+, respectively.  Calculate the #moles reacted by adding NaOH or HCl and see if you can form a buffer solution with the pH you want from it.

[Answer: see above]

Answer 3

e is correct choice.

ii NH3 + HCl --------> NH4Cl

v NH4Cl + NaOH --------> NH3 + NaCl +H2O

so it like NH4Cl in NH3 solution. This solution can be buffer solution.