Adsorption: physisorption vs chemisorption, Freundlich and Langmuir isotherms

55 questions on Adsorption: physisorption vs chemisorption, Freundlich and Langmuir isotherms from the Surface Chemistry chapter: 11 NEET level, 22 JEE Main, 22 JEE Advanced. Each one opens with its answer and solution.

• The main type of force responsible for physical adsorption (physisorption) of a gas on a solid surface is: NEET level
• The enthalpy of adsorption for chemisorption is typically in the range of: NEET level
• At constant pressure, on increasing the temperature the extent of physisorption of a gas on a solid generally: NEET level
• Which of the following statements about chemisorption is correct? NEET level
• The Freundlich adsorption isotherm for a gas on a solid, where x is the mass of gas adsorbed on mass m of adsorbent at pressure p, is: NEET level
• In the Freundlich isotherm x/m = k p^1/n, the extent of adsorption becomes independent of pressure when 1/n equals: NEET level
• The adsorption of a gas on charcoal increases when the charcoal is: NEET level
• At the same temperature and pressure, which gas is adsorbed to the greatest extent on activated charcoal? NEET level
• For the adsorption of a gas on a solid surface, the signs of Delta H and Delta S of the process are, respectively: NEET level
• Which of the following is NOT an assumption of the Langmuir adsorption isotherm? NEET level
• For the Freundlich isotherm, a plot of log(x/m) against log p is a straight line whose slope is: NEET level
• In the Langmuir isotherm theta=(Kp)/(1+Kp), the order of adsorption with respect to gas pressure at very low and at very high pressure is, respectively: JEE Main level
• Critical temperatures (in K) are: H2 33, N2 126, CO2 304, NH3 405. Assuming only physisorption on charcoal at the same temperature and pressure, the gas adsorbe... JEE Main level
• For adsorption obeying x/m=kp^1/n with n=3, the pressure is increased eight-fold at constant temperature. The amount adsorbed per gram changes by a factor of: JEE Main level
• A gas obeys the Langmuir isotherm with K=0.040 kPa^-1. The pressure at which half the surface sites are occupied is: JEE Main level
• A gas obeys theta=Kp/(1+Kp) with K=0.50 atm^-1. The fractional surface coverage at p=8.0 atm is: JEE Main level
• For a Langmuir adsorption, the pressure needed to reach 90% coverage is how many times the pressure needed to reach 50% coverage at the same temperature? JEE Main level
• Assertion (A): Physisorption of a gas on a solid decreases as temperature is raised at constant pressure. Reason (R): Adsorption is an exothermic process. Choos... JEE Main level
• A log-log plot for adsorption of a gas on a solid is linear with slope 0.50 and intercept 0.602 on the log(x/m) axis (take log 4=0.602). The value of x/m (same ... JEE Main level
• At constant pressure, the extent of chemisorption of a gas on a solid varies with temperature as follows: JEE Main level
• Which of the following is an example of chemisorption? JEE Main level
• For adsorption of a gas on charcoal, x/m=k p^1/n with k=2.4 mg g^-1 atm^-1/n and 1/n=0.40. Calculate x/m in mg g^-1 at p=3.0 atm. Use 3^0.4=1.55 if needed; give... JEE Main level
• In a Freundlich study, x/m=1.5 g/g at p=0.20 atm and x/m=4.5 g/g at p=1.8 atm. The data fit x/m=kp^1/n with n=2 exactly. Calculate k (in g g^-1 atm^-1/2) to two... JEE Main level
• A gas follows the Langmuir isotherm with K=0.35 kPa^-1. Find the fractional coverage theta at p=12 kPa (two decimal places). JEE Main level
• A powdered solid adsorbs a monolayer of 5.6 cm^3 (at STP) of nitrogen per gram. Each N2 molecule covers 0.16 nm^2. Taking molar volume at STP =22400 cm^3 mol^-1... JEE Main level
• 100 mL of 0.500 M acetic acid is shaken with 2.5 g of charcoal. At equilibrium the concentration is 0.436 M. Taking the molar mass of acetic acid as 60 g mol^-1... JEE Main level
• A gas is adsorbed according to the Langmuir isotherm with K=0.045 kPa^-1. At what pressure (in kPa, nearest integer) is 75% of the surface covered? JEE Main level
• Charcoal adsorbs a gas with monolayer capacity 7.2 cm^3 g^-1 (at STP) and Langmuir constant K=0.25 kPa^-1. At p=6.0 kPa, what volume of gas (in cm^3 at STP, nea... JEE Main level
• Which of the following statements about physisorption are correct? JEE Main level
• Which of the following statements about chemisorption are correct? JEE Main level
• Which of the following statements about the Freundlich isotherm x/m=kp^1/n for a gas are correct? JEE Main level
• Which of the following statements about the Langmuir isotherm theta=Kp/(1+Kp) are correct? JEE Main level
• For the physisorption of a gas on a solid surface at constant temperature, which of the following are correct? JEE Main level
• Two gases A and B follow Langmuir isotherms separately on the same surface at the same temperature, with K_A=0.50 kPa^-1 and K_B=0.20 kPa^-1. Each gas is used a... JEE Advanced level
• Gas A alone on a surface at its partial pressure gives theta_A=0.50 (Langmuir). Gas B is now added, adsorbing on the same sites with K_Bp_B=3.0 while p_A is unc... JEE Advanced level
• At a constant surface coverage, the pressure needed for a given amount of adsorption was measured at several temperatures. A plot of log_10p against 1/T is line... JEE Advanced level
• A diatomic gas adsorbs dissociatively on a surface, so that theta=dfrac(Kp)^1/21+(Kp)^1/2. At very low coverage, the pressure is increased nine-fold. The covera... JEE Advanced level
• Assertion (A): The Freundlich isotherm cannot describe adsorption at very high pressure of a gas. Reason (R): The Freundlich equation predicts that the amount a... JEE Advanced level
• Consider the statements: (i) Physisorption has an enthalpy of adsorption of about 20 to 40 kJ mol^-1. (ii) Chemisorption is confined to a monolayer. (iii) Physi... JEE Advanced level
• For a Langmuir adsorption, a plot of p/V (in kPa g cm^-3) against p (in kPa) gives a straight line of slope 0.0500 g cm^-3 and intercept 0.400 kPa g cm^-3 on th... JEE Advanced level
• A dye in 0.50 L of solution is adsorbed on 2.0 g of adsorbent obeying x/m=kC (Freundlich with 1/n=1, C = equilibrium concentration) with k=0.15 L g^-1. The frac... JEE Advanced level
• For a Freundlich isotherm x/m=kp^1/n with 0<1/n<1, the plot of x/m against p is: JEE Advanced level
• At a fixed surface coverage, a gas needs a pressure of 10 kPa at 300 K and 40 kPa at 320 K. Use ln(p_2/p_1)=(Delta H)/(R)((1)/(T_2)-(1)/(T_1)) with R=8.314 J mo... JEE Advanced level
• A gas adsorbs on a solid following the Langmuir isotherm. At T constant, the volume adsorbed (STP) per gram is 10.0 cm^3 at 8.0 kPa and 15.0 cm^3 at 24.0 kPa. P... JEE Advanced level
• Nitrogen adsorbs on a catalyst following the Langmuir isotherm. The volumes adsorbed (STP) per gram are 4.0 cm^3 at 8.0 kPa and 6.0 cm^3 at 24.0 kPa. Each N2 mo... JEE Advanced level
• A dye solution (1.00 L, 100 mg L^-1) is shaken with 2.0 g of an adsorbent. At equilibrium, x/m=ksqrtC with k=5.0 mg g^-1 (mg L^-1)^-1/2, where C is the equilibr... JEE Advanced level
• Gases A and B adsorb competitively on the same sites (competitive Langmuir): theta_A=(K_Ap_A)/(1+K_Ap_A+K_Bp_B). Given K_A=0.40 kPa^-1, p_A=5.0 kPa, K_B=0.10 kP... JEE Advanced level
• A diatomic gas adsorbs with dissociation, so theta=dfrac(Kp)^1/21+(Kp)^1/2. At a pressure p_1 the coverage is 0.40. Find the coverage when the pressure is raise... JEE Advanced level
• Nitrogen adsorption on a solid follows x/m=kp^1/n. The values are x/m=6.0 mg g^-1 at 0.20 atm and 12.0 mg g^-1 at 0.80 atm. Find the number of N2 molecules (in ... JEE Advanced level
• Adsorption data for a gas on a solid give x/m=2.0, 4.0, 6.0 mg g^-1 at p=1, 4, 9 atm respectively, fitting the Freundlich equation exactly. Which statements are... JEE Advanced level
• A gas obeys the Langmuir isotherm with K=0.125 kPa^-1. Which statements are correct? JEE Advanced level
• For adsorption of a gas on a solid, considering the dependence of equilibrium pressure on temperature at constant coverage, which statements are correct? JEE Advanced level
• Which of the following observations indicate chemisorption rather than physisorption? JEE Advanced level
• 0.50 L of a dye solution of 80 mg L^-1 is stirred with 2.0 g of adsorbent. The equilibrium concentration is 32 mg L^-1. Assume x/m=kC (Freundlich, 1/n=1). Which... JEE Advanced level
• Gases A and B adsorb competitively on the same sites (competitive Langmuir) with K_Ap_A=2.0 and K_Bp_B=2.0. Which statements are correct? JEE Advanced level