Coagulation, Hardy-Schulze rule, protective colloids

29 questions on Coagulation, Hardy-Schulze rule, protective colloids from the Surface Chemistry chapter: 6 NEET level, 14 JEE Main, 9 JEE Advanced. Each one opens with its answer and solution.

• Which of the following ions is the most effective in coagulating a negatively charged As2S3 sol? NEET level
• Which of the following is the most effective in coagulating a positively charged Fe(OH)3 sol? NEET level
• The gold number of a protective colloid is the number of milligrams of it that just prevent the coagulation of 10 mL of a standard gold sol on adding 1 mL of 10... NEET level
• A lyophilic colloid that is added to a lyophobic sol to prevent its coagulation by electrolytes is called a: NEET level
• When a positively charged Fe(OH)3 sol is mixed with a negatively charged As2S3 sol in suitable proportions, the result is: NEET level
• The flocculation value of an electrolyte for a given sol is defined as: NEET level
• Which of the following orders correctly shows increasing coagulating power of the electrolytes towards a negatively charged As2S3 sol? JEE Main level
• Which order represents decreasing coagulating power of the following electrolytes for a positively charged Fe(OH)3 sol? JEE Main level
• 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
• Assertion (A): Al^3+ ions coagulate a gold sol at a much lower concentration than Na+ ions. Reason (R): Gold sol is negatively charged, and the coagulating effe... 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 origin of charge are bes... 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 per litre of sol (vo... 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 2.7 mg of a protein j... JEE Main level
• The flocculation values (mmol/L) of NaCl, BaCl2 and AlCl3 for an As2S3 sol are 52, 0.69 and 0.093. Taking the coagulating power of NaCl as 1 and defining coagul... JEE Main level
• The flocculation value of KCl for a positively charged sol is 36 mmol per litre of sol. What volume of 0.12 M KCl solution is needed to coagulate 350 mL of the ... JEE Main level
• According to the Schulze-Hardy rule in the convention that the flocculation value of a counter-ion varies as 1/z^6 (z = charge of the coagulating ion), the floc... JEE Main level
• Select the correct statement(s) regarding coagulation of colloidal sols. JEE Main level
• Select the correct statement(s) comparing lyophilic and lyophobic sols. JEE Main level
• A positively charged sol (40.0 mL) is just coagulated by 8.0 mL of 0.25 M Na2SO4 solution. The effective ion is the anion. Taking the concentration of the coagu... JEE Advanced level
• A commercial sample of a protective colloid is only 80% pure by mass (the impurity has no protective action). 1.25 mg of the sample just protects 25 mL of a gol... JEE Advanced level
• For a certain negative sol the flocculation values are 50 mmol/L for NaCl and 0.80 mmol/L for CaCl2. Assume that the coagulating effects of the two salts are ad... JEE Advanced level
• The flocculation value of AlCl3 for an As2S3 sol is 0.093 mmol per litre of sol. What mass of anhydrous AlCl3 (Al = 27, Cl = 35.5) in mg is needed to coagulate ... JEE Advanced level
• The flocculation values (mmol/L) for a sol are: NaCl 55, Na2SO4 54, CaCl2 0.70 and MgSO4 0.72. Which conclusion is correct? JEE Advanced level
• Protective colloid X has gold number 0.15 and protective colloid Y has gold number 0.60 (mg per 10 mL of gold sol). Protection is additive, i.e. the sol volume ... JEE Advanced level
• Four sols are available: P (As2S3), Q (Fe(OH)3), R (gold) and S (Al(OH)3). Which of the following pairs, when mixed in suitable proportions, show mutual coagula... JEE Advanced level
• The flocculation values (mmol/L) of KCl, MgCl2 and AlCl3 for a sol are 90, 1.2 and 0.10. Select the correct statement(s). JEE Advanced level
• Protective colloids P, Q and R have gold numbers 0.02, 0.5 and 25 respectively (mg per 10 mL of gold sol). Select the correct statement(s). JEE Advanced level