Question

Gold sol is an example of:

Answer 1

In sol solid particles are suspended in liquid. They are a type of colloid. To find out what type of sol gold is they are to be identified on the basis of their charges, whether negatively charged or positively charged.

Complete answer:
First let’s try to understand what exactly a sol is and what all the types of sol is. Then we will be able to identify the sol of gold.
A sol, as mentioned in the hint, is a colloid (aggregate of very fine particles dispersed in a continuous medium) in which the particles are in solid state and the dispersion medium is in liquid or fluid state. The sol particles are very small in size. They are stable and show a tyndall effect. The method of preparation of sol is condensation or dispersion. Some of the examples of sol are pigmented liquid ink, paint and blood.
They are one of the types of colloids. Other types of colloids are emulsion, foam and aerosol.
There are different types of sol -
Lyophilic sol- The dispersed phase particles have great affinity for the dispersion medium. These are reversible sols. Example-Rubber
Lyophobic sol- The dispersed phase particles have no affinity for the dispersion medium. Example- Gold.
Hydrophobic sol- They are easily coagulated sol and are less stable
Hydrophilic sol- They are more stable due to charge and solvation properties.
Now that we are familiar with the sol and its type we can answer the question. The gold sol is a lyophobic sol. It aggregates together and forms a colloid. In case of their charge, they are negatively charged.

Note:
The sol particles acquire positive or negative charge by the adsorption of positive or negative ions. Positively charged sols are mostly metal hydroxides and negatively charged sols are metal or metal sulphide sols.