Question

Question: Among the electrolytes $N{a_2}S{O_4},CaC{l_2},A{l_2}{\left( {S{O_4}} \right)_3}$ and $N{H_4}Cl$ the most effective coagulating agent for $S{b_2}{S_3}$ solution is:
A: $N{a_2}S{O_4}$
B: $CaC{l_2}$
C: $A{l_2}{\left( {S{O_4}} \right)_3}$
D: $N{H_4}Cl$

Answer 1

In coagulation some chemical substances are added in a solution that causes small particles that are suspended in the solution to convert into large molecules. In this process a large number of small particles is converted into a small number of large particles.

Complete step by step answer:
Coagulation is the process in which some chemicals are added that cause large numbers of small particles to convert into small numbers of large particles. The chemicals that are added in this process are called coagulating agents. In this question we have to find the suitable coagulating agent for $S{b_2}{S_3}$ solution. $S{b_2}{S_3}$ is antimony trisulphide. Antimony trisulphide is negatively charged sol. This means for the coagulation of antimony trisulphide we will need a strong positively charged sol. Among the given options all the electrolytes are positively charged. So, we will have to find the electrolyte that has maximum positive charge. Charge on one sodium atom is $+ 1$ as it has only one electron to lose in its valence shell. Charge on calcium is $+ 2$ as it has two electrons in its valence shell to lose. Charge on aluminium is $+ 3$ as it has three electrons in its valence shell to lose. Charge on chloride ion is $- 1$ as it needs only one electron to complete its octet, so charge on $N{H_4}$ is $+ 1$. So, among the given options aluminium has maximum positive charge. This means aluminium electrolyte will be most suitable for coagulation of $S{b_2}{S_3}$.

This means the correct answer is option C that is $A{l_2}{\left( {S{O_4}} \right)_3}$ .

Note:
Particles of colloid can’t be separated by filtration. But a technique centrifugation can be used to separate colloid particles. In centrifugation particles are suspended in a liquid medium and then the tube containing particles is placed in a rotor and spun at a definite speed.