surfactants

Question 1

what is interface?

Answer 1

boundary between 2 phases

Question 2

what is a surface?

Answer 2

boundary between 2 phases when 1 is a gas

Question 3

what is surface energy?

Answer 3

potential energy per unit surface area

Question 4

what lowers a molecules surface energy?

Answer 4

intermolecular bonds

Question 5

what is surface tension?

Answer 5

‘film’ on surface that resists puncture
energy required to expand the surface of a liquid by a unit area

Question 6

2 techniques to measure surface tension?

Answer 6

ring - cylinder in and out
plate - dip something in and out

Question 7

what does contact angle indicate?

Answer 7

indicates surface wettability

Question 8

what does a larger contact angle mean?

Answer 8

less wettability

Question 9

what is wettability?

Answer 9

tendency of liquid to adhere to a solid surface

Question 10

how do surfactants work?

Answer 10

reduce surface tension by reducing bonding between water

Question 11

how are micelles formed?

Answer 11

when a liquid is saturated with a surfactant the excess sinks below surface

Question 12

what is CMC?

Answer 12

critical micelle concentration
minimum conc. of surfactant when micelles form

Question 13

what is Traube’s rule?

Answer 13

molar conc. of surfactant needed to achieve a certain surface tension decreases by around 3 fold with each CH2 unit in homologous series