Answer:
c. 0.2 M HNO₃ and 0.4 M NaF .
Explanation:
A buffer is defined as the mixture of a weak acid with its conjugate base or a weak base with its conjugate acid.
A weak acid or weak base are defined as an acid or base that partially dissociates in aqueous solution. in contrast, a strong acid or base are acids or bases that is dissociated completely in water.
Thus:
a. 0,2M HNO₃ and 0.4 M NaNO₃. This is a mixture of a strong acid with its conjugate base. IS NOT a buffer.
b. 0.2 M HNO₃ and 0.4 M HF . This is a mixture of two strong acids. IS NOT a buffer.
c. 0.2 M HNO₃ and 0.4 M NaF . NaF is the conjugate base of a weak acid as HF is.
The reaction of HNO₃ with NaF is:
HNO₃ + NaF → HF + NaNO₃
That means that in solution you will have a weak acid (HF) with its conjugate base (NaF). Thus, this mixture IS a buffer.
d. 0.2 M HNO₃ and 0.4 M NaOH. This is the mixture of a strong acid with a strong base, thus, this IS NOT a buffer.
I hope it helps!
The mixtures which would result in a buffered solution when the two solutions are mixed is 0.2 M HNO₃ and 0.4 M NaF .
A buffer is defined as a substance which is able to resist changes in pH of a solution.It usually comprises of the mixture of a weak acid with its conjugate base or a weak base with its conjugate acid.
The reaction between HNO₃ and NaF can be deduced below:
HNO₃ + NaF → HF + NaNO₃
We can deduce that a weak acid is HF with its conjugate base as being NaF thereby making option C the most appropriate choice.
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