[CHEM] Properties of Liquid Viscosity & Surface Tension

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3. - is defined as a measure of a fluid's
resistance to flow.
- A fluid with large viscosity resists motion
because its molecular makeup gives it a lot of
internal friction. A fluid with low viscosity flows
easily because its molecular makeup results in
very little friction when it is in motion.
- The liquid's viscosity is influenced by the size,
shape, and attraction of the particles that
make up the liquid. Low-viscosity liquids flow
more swiftly (i.e., water, rubbing alcohol, and
vegetable oil). Highly viscous liquids move
slowly (i.e., honey, corn syrup, and molasses).
WHAT IS VISCOSITY?

4. FACTORS OF VISCOSITY
- Temperature
Greater average kinetic energy and faster-moving molecules are both
correlated with higher temperatures. As the temperature increases, the
kinetic energy of the molecules increases, and hence the force of
cohesion between them decreases. Thus, the viscosity of liquid decreases
with an increase in temperature.
- Pressure
The viscosity of liquid (except water) increases with an increase in
pressure. In the case of water, the viscosity decreases with an increase in
pressure.

5. FACTORS OF VISCOSITY
- Density
The viscosity of liquid increases with an increase in density. The
viscosity of thick (i.e. dense) liquids like glycerin, honey, coaltar, etc
is more than thin liquids like water.
- Molecular Structure
The viscosity will also be influenced by the shape of the molecules
since large, branching, or kinked molecules will be more difficult to
"slide by" than small, "round" ones.

6. DYNAMIC
VISCOSITY
KINEMATIC
VISCOSITY
Also known as absolute
viscosity, and is related
to the force under which
the fluid is subjected.
This is how a fluid resists the pull of
gravity. The measurement is
dependent on the density of a
fluid.
TYPES OF VISCOSITY:

7. WHAT IS THE
RELATION OF IMF TO
VISCOSITY?

8. - Viscosity is governed by the strength of
intermolecular forces and especially by the
shapes of the molecules of a liquid. Liquids
whose molecules are polar or can form
hydrogen bonds are usually more viscous
than similar nonpolar substances.
- Viscosity increases with stronger molecular
forces and decreases with high temperatures.
- The stronger the intermolecular force, the
more the molecules will the attracted to one
another, leading to a higher viscosity.
WHAT IS THE RELATION OF
IMF TO VISCOSITY?

9. Water with low viscosity flows quickly.
Honey with high viscosity flows slowly.
Motor oil, in the winter, flowing from its
container flows slow, but in the summer it
flows fast.
Pancake syrup, just out of the refrigerator,
flowing from the bottle flows slow, but
when warmed up by placing it under
warm water will flow fast.
EXAMPLES

11. - Surface tension is the tendency of fluid surfaces to
shrink into the minimum surface area possible.
- It is the phenomenon that occurs when the surface
of a liquid is in contact with another phase. Liquids
tend to acquire the least surface area possible. The
surface of the liquid behaves like an elastic sheet.
WHAT IS
SURFACE TENSION?

12. COHESIVE
FORCES
ADHESIVE
FORCES
is a generic term for the collective
intermolecular forces (e.g.,
Hydrogen bonding and Van der
Waals forces) responsible for the
bulk property of liquids resisting
separation. Specifically, these
attractive forces exist between
molecules of the same substance.
refers to the attractive forces
between unlike substances, such
as mechanical forces (sticking
together) and electrostatic forces
(attraction due to opposing
charges). In the case of a liquid
wetting agent, adhesion causes
the liquid to cling to the surface on
which it rests.
FORCES INVOLVED IN
SURFACE TENSION

13. WHAT IS THE
RELATION OF IMF TO
SURFACE TENSION?

14. - The surface tension of a liquid results from
an imbalance of intermolecular attractive
forces. The strength of IMF (intermolecular
forces) and the surface area of a molecule are
directly related to one another, that is, the
strength of IMF increases with increasing
surface area of the concerned molecule.
- The correlation between the surface tension
of a liquid and the strength of the
intermolecular forces: the stronger the
intermolecular forces, the higher the surface
tension.
WHAT IS THE RELATION OF
IMF TO SURFACE TENSION?

15. Insects walking on water
Floating a needle on the surface of the
water.
Cleaning of clothes by soaps and
detergents which lowers the surface
tension of the water
Washing with cold water
Round bubbles where the surface tension of
water provides the wall tension for the
formation of water bubbles.
EXAMPLES

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Airlines
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11 PLATO | MEMBERS: ALGARA,
AUSTRIA, CABANGBANG, DAVID,
AUSTRIA, CABANGBANG, DAVID,
AUSTRIA, CABANGBANG, DAVID,
DELOS REYES, PADUA, ROY, SANTOS
DELOS REYES, PADUA, ROY, SANTOS
DELOS REYES, PADUA, ROY, SANTOS

17. References:
Surface tension. (2021, February 22). BYJUS. https://byjus.com/physics/surface-tension/
L. (2023, January 30). Cohesive and Adhesive Forces. Chemistry LibreTexts.
https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_M
odules_(Physical_and_Theoretical_Chemistry)/Physical_Properties_of_Matter/States_of_Matter/Properties_of
_Liquids/Cohesive_and_Adhesive_Forces
L. (2020, August 14). 11.4: Intermolecular Forces in Action- Surface Tension, Viscosity, and Capillary Action. Chemistry
LibreTexts.
https://chem.libretexts.org/Bookshelves/General_Chemistry/Map%3A_A_Molecular_Approach_(Tro)/11%3A_Liqui
ds_Solids_and_Intermolecular_Forces/11.04%3A_Intermolecular_Forces_in_Action-
_Surface_Tension_Viscosity_and_Capillary_Action#:~:text=Note%20the%20correlation%20between%20the,the%2
0higher%20the%20surface%20tension.
Merocourse. (n.d.). What is Viscosity? | 3 Factors Affecting Viscosity. https://blog.merocourse.com/what-is-
viscosity-factors-affecting-viscosity/
Bell-Young, L. (2021, November 3). What is Viscosity in Chemistry? The Chemistry Blog.
https://www.chemicals.co.uk/blog/what-is-viscosity-in-chemistry
Chemistry 301. (n.d.). Viscosity. http://ch301.cm.utexas.edu/imfs/#liquids/viscosity.html
Vitz, E., Moore, J.W., Shorbe, J., Prat-Resina, X., Wendorff, T. & Hahn, A. (2022, April 3). 10.7: Viscosity. Chemistry
LibreTexts.
https://chem.libretexts.org/Bookshelves/General_Chemistry/Book%3A_ChemPRIME_(Moore_et_al.)/10%3A_Solid
s_Liquids_and_Solutions/10.07%3A_Viscosity