Answer:
pH = -0.32
Explanation:
The reaction of HIO₃ with NaOH is:
HIO₃ + NaOH → IO₃⁻ + Na⁺ + H₂O
Moles that react are:
15.00mL = 0.015L * (0.800mol / L) = 0.012 moles HIO₃
45.00mL = 0.045L * (0.0200 mol / L) = 9x10⁻⁴ moles NaOH.
The moles of NaOH that reacts are equal to moles of IO₃⁻, and moles of HIO₃ are:
0.012 mol - 9x10⁻⁴ moles = 0.0111 moles HIO₃
Now, the mixture of a weak acid, HIO₃ and IO₃⁻, its conjugate base, produce a buffer. The pH of the buffer is obtained using H-H equation:
pH = pKA + log [IO₃⁻] / [HIO₃]
Where [] could be taken as moles of each compound.
Replacing:
pH = 0.77 + log [9x10⁻⁴ moles IO₃⁻] / [0.0111 moles HIO₃]
pH = -0.32
Yes, it is possible to have negative pH's!
