13 Questions
Which of the following is a possible origin of surface charges on materials immersed in an aqueous solution?
Dissociation of the surface functional groups
Which of the following is true about surface-active agents or surfactants?
They contain both polar hydrophilic and non-polar hydrophobic groups
What are the five main interfaces identified in nature?
- liquid-gas, 2. liquid-liquid, 3. solid-liquid, 4. solid-gas, and 5. solid-solid
What is the thermodynamic relation between the extent of adsorption and the change in the surface tension of the solution known as?
Gibbs adsorption isotherm
Which of the following statements about surface tension is true based on the information provided?
Surface tension is the energy required to bring a molecule from the bulk to the surface of a liquid.
Which of the following is true about the thermodynamic state of the surface of a liquid compared to the bulk of the liquid?
The thermodynamic state of the surface of a liquid is different from the bulk of the liquid.
Which of the following is a possible cause of surface charges on materials immersed in an aqueous solution?
Dissociation of the surface functional groups
Which of the following is NOT a possible cause of surface charges on materials immersed in an aqueous solution?
Dissociation of the constituent surface atoms
Which of the following is true about surface-active agents or surfactants?
They decrease the surface tension of water.
What are the five main interfaces identified in nature?
- liquid-gas, 2. liquid-liquid, 3. solid-liquid, 4. solid-gas, and 5. solid-solid
What is the thermodynamic relation between the extent of adsorption and the change in the surface tension of the solution known as?
Gibbs adsorption isotherm
Which of the following statements about surface tension is true based on the information provided?
Surface tension is the energy required to bring a molecule from the bulk of the liquid to the surface.
Which of the following is true about the thermodynamic state of the surface of a liquid compared to the bulk of the liquid?
The surface of a liquid has a lower free energy compared to the bulk of the liquid.
Study Notes
Surface Charges and Surfactants
- Possible origins of surface charges on materials immersed in an aqueous solution include dissociation of ionizable groups, adsorption of ions, and rearrangement of electrons
- Surface-active agents or surfactants are molecules that reduce the surface tension of a solution, increasing the contact between the solution and another phase
Interfaces in Nature
- The five main interfaces identified in nature are solid-gas, solid-liquid, liquid-gas, liquid-liquid, and solid-solid interfaces
Surface Tension and Adsorption
- The thermodynamic relation between the extent of adsorption and the change in the surface tension of the solution is known as the Gibbs adsorption equation
- The extent of adsorption is directly related to the change in surface tension, with increased adsorption resulting in decreased surface tension
Thermodynamic State of the Surface
- The surface of a liquid is in a higher energy state compared to the bulk of the liquid, due to the presence of unsatisfied bonds and electrostatic forces
Causes of Surface Charges
- Possible causes of surface charges on materials immersed in an aqueous solution include electrostatic interactions, molecular interactions, and chemical reactions
- Ionization of surface groups, adsorption of ions, and changes in the electronic configuration of the surface are NOT the only possible causes of surface charges on materials immersed in an aqueous solution
Test your knowledge on surface phenomena in this quiz! Learn about the different properties that exist at the exterior and interior of phases and understand the concept of phase equilibria.
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