Assertion (A): $Al X^{3 +}$ ions coagulate a gold sol at a much lower concentration than $Na X^{+}$ ions. Reason (R): Gold sol is negatively charged, and the coagulating effect of the oppositely charged ion increases with its charge.

ABoth A and R are true and R is the correct explanation of A
BBoth A and R are true but R is not the correct explanation of A
CA is true but R is false
DA is false but R is true

Answer: A

Gold sol is negative, so cations coagulate it, and by the Hardy-Schulze rule a higher charge on the cation lowers the flocculation value. Thus A is true, R is true, and R explains A.

Practice Surface Chemistry More on Coagulation, Hardy-Schulze rule, protective colloids

Previous questionNext question

More questions on Coagulation, Hardy-Schulze rule, protective colloids

The flocculation values (in mmol per litre) of KCl, K2SO4 and K3[Fe(CN)6] for a certain sol are 100, 0.65 and 0.09 respectively. The sol is: JEE Main level
The gold numbers of gelatin, gum arabic and potato starch are 0.01, 0.15 and 25 respectively. Which statement is correct? JEE Main level
A lyophilic sol needs a much higher electrolyte concentration to coagulate than a lyophobic sol of similar charge mainly because: JEE Main level
A freshly precipitated Fe(OH)3 is converted into a stable sol by shaking it with a small amount of FeCl3 solution. This process and the orig... JEE Main level
To coagulate 20.0 mL of a gold sol, 5.0 mL of 0.50 M NaCl solution is needed. Flocculation value is the number of millimoles of electrolyte ... JEE Main level
Gold number is the mass of protective colloid, in mg, that just prevents coagulation of 10 mL of a gold sol on adding 1 mL of 10% NaCl. If 2... JEE Main level

Assertion (A): AlX3+ ions coagulate a gold sol at a much lower concentration than NaX+ ions. Reason (R): Gold sol is negatively charged, and the coagulating effect of the oppositely charged ion increases with its charge.

Answer: A

More questions on Coagulation, Hardy-Schulze rule, protective colloids

Assertion (A): $Al X^{3 +}$ ions coagulate a gold sol at a much lower concentration than $Na X^{+}$ ions. Reason (R): Gold sol is negatively charged, and the coagulating effect of the oppositely charged ion increases with its charge.