Physical Chemistry Exam 100%
Correct!!
Where is surface chemistry used? - ANSWER Surface chemistry is used in industry, wastewater
treatment, as well as in research for the respiratory field of medicine in premature babies.
What is an interface? - ANSWER Interface is a surface that forms a common boundary between two
bulk phases.
What can be the possible bulk phases? - ANSWER Solid - gas, solid - liquid, liquid - liquid, liquid - gas.
Why does solid - solid phase not meet the requirement? - ANSWER Due to atomic/molecular
bonding. It restricts reorientation. If two cubes of solid material were put close to one another, the
mixing of the two phases would not occur due to the nature of a solid.
Why does gas - gas phase not meet the requirement? - ANSWER Inherent miscibility shows that if a
gas - gas phase was used, all particles would quickly mix with each other, thus not providing a
boundary.
What is surface tension? - ANSWER Surface tension is energy (work) required to expand the surface
area of a liquid by unit area.
Give a surface tension expression. - ANSWER dw = ydo
dw - work done
y (gamma) - surface tension
do - change in surface area
What are the units for calculating surface tension? - ANSWER Joules per metre (J m-1) or Newtons
per metre (N m-1). Can also be measured in dynes. 1 N = 100 000 dynes.
What is cohesion? - ANSWER Cohesion is an attraction between molecules of the same substance.
What is adhesion? - ANSWER An attraction between molecules of different substances.
Correct!!
Where is surface chemistry used? - ANSWER Surface chemistry is used in industry, wastewater
treatment, as well as in research for the respiratory field of medicine in premature babies.
What is an interface? - ANSWER Interface is a surface that forms a common boundary between two
bulk phases.
What can be the possible bulk phases? - ANSWER Solid - gas, solid - liquid, liquid - liquid, liquid - gas.
Why does solid - solid phase not meet the requirement? - ANSWER Due to atomic/molecular
bonding. It restricts reorientation. If two cubes of solid material were put close to one another, the
mixing of the two phases would not occur due to the nature of a solid.
Why does gas - gas phase not meet the requirement? - ANSWER Inherent miscibility shows that if a
gas - gas phase was used, all particles would quickly mix with each other, thus not providing a
boundary.
What is surface tension? - ANSWER Surface tension is energy (work) required to expand the surface
area of a liquid by unit area.
Give a surface tension expression. - ANSWER dw = ydo
dw - work done
y (gamma) - surface tension
do - change in surface area
What are the units for calculating surface tension? - ANSWER Joules per metre (J m-1) or Newtons
per metre (N m-1). Can also be measured in dynes. 1 N = 100 000 dynes.
What is cohesion? - ANSWER Cohesion is an attraction between molecules of the same substance.
What is adhesion? - ANSWER An attraction between molecules of different substances.
