Video Transcript
The diagram provided shows
colloidal particles dispersed in a liquid. An electrolyte is then added to the
colloidal mixture. What effect does the electrolyte
have on the colloids? (A) The ions in the electrolyte
neutralize the charges on the colloidal particles, allowing them to form heavy
aggregates and settle out of the liquid. (B) The ions in the electrolyte
increase the solubility of the colloidal particles, converting the colloidal system
into a solution. (C) The ions in the electrolyte
reduce the vapor pressure and stop the colloids from evaporating out of the
liquid. (D) The addition of an electrolyte
changes the dispersed phase of the colloids. (E) The addition of an electrolyte
causes the colloidal particles to shrink.
When we first look at the diagram,
we notice that the large colloidal particles have positive charges. This means that the colloidal
particles will attract negative ions and can be balanced by them. Introducing an electrolyte, such as
sodium chloride, introduces additional positive and negative ions. However, the positive ions that are
introduced are generally smaller and do not have an effect. The negative ions, on the other
hand, are attracted to the large colloidal particles. The negative ions combine with the
colloidal particles, balancing their charge.
When the colloidal particles come
together, they create heavy aggregate particles that are neutral. Generally, neutral heavy aggregate
particles will precipitate and settle out of aqueous solutions. So when we introduce an electrolyte
to this colloid, it balances the charge on the colloidal particles, allowing them to
form heavy aggregates and settle out of the liquid.
If we apply this understanding to
the answer choices, we can see that answer choice (A) is correct. The ions in the electrolyte
neutralize the charges on the colloidal particles, allowing them to form heavy
aggregates and settle out of the liquid.
