Surface Chemistry - Physical Chemistry - Chemistry Previous Year Questions

Nitrogen gas is absorbed on 20% surface sites. On heating N\(_2\) gas evolved from sites and was collected at 0.01 atm and 298 K in a container of volume 2.46 cm\(^3\). Find out the number of surface sites occupied per molecule of N, if the density of surface sites is \(6.023\times10^{14}/\mathrm{cm^3}\) and surface area is 1000 cm\(^2\).

Statement 1 : Micelles are formed by surfactant molecules above the critical micellar concentration (CMC).

Statement 2 : The conductivity of a solution having surfactant molecules decreases sharply at the CMC.

Among the following, the surfactant that will form micelles in aqueous solution at the lowest molar concentration at ambient condition is:

Among the electrolytes Na\(_2\)SO\(_4\), CaCl\(_2\), Al\(_2\)(SO\(_4\))\(_3\) and NH\(_4\)Cl, the most effective coagulating agent for Sb\(_2\)S\(_3\) sol is

The given graphs/data I, II, III and IV represent general trends observed for different physisorption and chemisorption processes under mild conditions of temperature and pressure. Which of the following choice(s) about I, II, III and IV is(are) correct?

To form a complete monolayer of acetic acid on $1 \mathrm{~g}$ of charcoal, $100 \mathrm{~mL}$ of $0.5 \mathrm{M}$ acetic acid was used. Some of the acetic acid remained unadsorbed. To neutralize the unadsorbed acetic acid, 40 $\mathrm{mL}$ of $1 \mathrm{M} \mathrm{NaOH}$ solution was required. If each molecule of acetic acid occupies $\mathbf{P} \times 10^{-23} \mathrm{~m}^2$ surface area on charcoal, the value of $\mathbf{P}$ is _____.

[Use given data: Surface area of charcoal $=1.5 \times 10^2 \mathrm{~m}^2 \mathrm{~g}^{-1}$; Avogadro's number $\left(\mathrm{N}_{\mathrm{A}}\right)=6.0 \times 10^{23}$ $\left.\mathrm{mol}^{-1}\right]$

Adsorption of phenol from its aqueous solution on to fly ash obeys Freundlich isotherm. At a given temperature, from $10 \mathrm{mg} \mathrm{g}^{-1}$ and $16 \mathrm{mg} \mathrm{g}^{-1}$ aqueous phenol solutions, the concentrations of adsorbed phenol are measured to be $4 \mathrm{mg} \mathrm{g}^{-1}$ and $10 \mathrm{mg} \mathrm{g}^{-1}$, respectively. At this temperature, the concentration (in $\mathrm{mg} \mathrm{g}^{-1}$ ) of adsorbed phenol from $20 \mathrm{mg} \mathrm{g}^{-1}$ aqueous solution of phenol will be ______________.

Use: $\log _{10} 2=0.3$

At a given temperature, 0.45 g of acetic acid in 50 mL of water is shaken with 1.0 g of charcoal and the pH of the resulting solution is 3.0 . Assume, the adsorption of acetic acid from the aqueous solution by charcoal follows Freundlich isotherm,

$$\frac{x}{m}=k C^{1 / n}$$

If the plot of $\log _{10}(x / m)$ against $\log _{10} C$ gives a straight line with slope 1 , the value of $k$ in $\mathrm{L} \mathrm{mol}^{-1}$ is $\_\_\_\_$ .

Given: The molar mass of acetic acid is $60 \mathrm{~g} \mathrm{~mol}^{-1}$.

The acid dissociation constant of acetic acid is $1.0 \times 10^{-5}$ at the given temperature.

$x$ is the mass (in grams) of acetic acid adsorbed.

$m$ is the mass (in grams) of charcoal.

$C$ is the equilibrium concentration of acetic acid in the solution after the adsorption is complete.

$k$ and $n$ are constants for acetic acid-charcoal system at the given temperature.