Question

The addition of Monobasic Potassium Phosphate to the suspended Bismuth Subnitrate particles cause the A to B owing to the C:

• A. A–positive zeta potential, B–decrease, C–adsorption of the negatively charged phosphate anion
• B. A–negative zeta potential, B–decrease, C–adsorption of the negatively charged phosphate anion
• C. A–positive zeta potential, B–increase, C–adsorption of the negatively charged phosphate anion
• D. A–positive zeta potential, B–decrease, C–adsorption of the positively charged hydrogen anion

Answer 1

The Correct Option is A

To understand the scenario in this question, we need to delve into the effect of Monobasic Potassium Phosphate on suspended Bismuth Subnitrate particles in a solution, focusing on the impact on the zeta potential and particle stability.

Definition and Concepts:

• Zeta potential is a scientific term for the electric potential at the slipping plane of a particle in suspension, which is affected by the charge distribution in the surrounding liquid.
• The charge on the particle impacts its stability in suspension; a higher magnitude zeta potential means greater inter-particle repulsion and thus more stable colloidal suspension.
• Monobasic Potassium Phosphate is known for providing phosphate ions upon dissociation in solution.

Explanation:

• When Monobasic Potassium Phosphate is added, it dissociates in the solution to yield phosphate ions (PO_4^{3-}), which are negatively charged.
• These negatively charged phosphate ions are adsorbed onto the surface of the Bismuth Subnitrate particles, which increases the overall negative charge on the particles' surface.
• This results in a shift of the zeta potential towards the negative side, effectively increasing the negative zeta potential.
• An increase in negative zeta potential usually results in decreased aggregation of the suspended particles due to enhanced repulsion forces between them.

Correct Option Evaluation:

• The correct option is:
  A–negative zeta potential, B–decrease, C–adsorption of the negatively charged phosphate anion
  .
• The adsorption of negatively charged phosphate ions results in a negative zeta potential on the Bismuth Subnitrate particles.
• This negative zeta potential causes the particles to be more stable in suspension due to the increased repulsion, leading the interactions between the particles to decrease.

Thus, the addition of Monobasic Potassium Phosphate leads to a more stable suspension of bismuth subnitrate particles by modifying the zeta potential through the adsorption of negatively charged phosphate ions.