How can you experimentally determine the pk_a of acetic acid? determine the ph of the solution 1/4 of the way to the end-point on the ph titration curve for acetic acid. determine the ph of the solution half way to the end-point on the ph titration curve for acetic acid. determine the ph at the end-point on the ph titration curve for acetic acid.

Determine the pH of the solution half-way to the end-point on the pH titration curve for acetic acid.  

Explanation:

The equation for the ionization of acetic acid is

HA + H₂O ⇌ H₃O⁺ + A⁻

For points between the starting and equivalence points, the pH is given by the Henderson-Hasselbalch equation:

At the half-way point, half of the HA has been converted to A⁻, so [HA] = [A⁻].  Then,

The pKₐ is the pH at the half-way point in the titration.

b is the correct

assuming that your periodic table has eighteen columns, you should highlight   the four elements in the third column from the left of the table.

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the have energy higher than those in the orbital while lower than those of the orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the orbital is therefore filled right after orbitals and before orbitals.  

potassium has electron configuration and calcium . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the and should be highlighted as well.