Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.
Prepared by :-
Abhishek
Observing the Natural World of Matter
What Is Matter?
Matter is the material or “stuff” everything is made of.
What are yo...
Solid, Liquid, Gas
(a) Particles in solid (b) Particles in liquid (c) Particles in gas
Ice
H2O(s) Ice
Photograph of ice model Photograph of snowflakes
Liquid
H2O(l) Water
In a liquid
• molecules are in
constant motion
• there are appreciable
intermolecular forces
• molecul...
Gas
H2O(g) Steam
Liquids
The two key properties we need to describe are
EVAPORATION and its opposite CONDENSATION
add energy and break inte...
States of Matter
Solid Liquid Gas
Holds Shape
Fixed Volume
Shape of Container
Free Surface
Fixed Volume
Shape of Container...
Some Properties of Solids, Liquids, and Gases
Property Solid Liquid Gas
Shape Has definite shape Takes the shape of Takes ...
• To evaporate, molecules must have sufficient
energy to break IM forces.
• Molecules at the surface break away and
become...
Change from gas to liquid
Achieves a dynamic equilibrium with vaporization in
a closed system.
What is a closed system?
A ...
As time goes by the rate of vaporization remains
constant but the rate of condensation
increases because there are more mo...
• Vaporization is an endothermic process - it
requires heat.
• Energy is required to overcome intermolecular
forces
• Resp...
Energy Changes Accompanying Phase Changes
Solid
Liquid
Gas
Melting Freezing
Deposition
CondensationVaporization
Sublimatio...
Density & Specific gravity
Density:-The density of a material is equal to its mass divided by its volume and has units of
...
Viscosity
Viscosity may be thought of as a liquid’s internal resistance to
flow. A liquid can be envisaged as having a ser...
Van der Waals Forces and the Properties of
Liquids
• Viscosity increases with increasing intermolecular forces because
inc...
Continue…
Pseudo plastic fluid – Viscosity decreases as the shear rate increases
(e.g. emulsions, and suspensions such as...
Surface Tension
• Surface tension is the
tendency for liquid
surface to contract.
• Depends on attractive
forces
• Compoun...
Van der Waals Forces and the Properties of
Liquids
• Surface tension increases with increasing intermolecular forces.
– Su...
The molecular basis of surface tension.
hydrogen bonding
occurs in three
dimensions
hydrogen bonding
occurs across the sur...
Shape of water or mercury meniscus in glass.
adhesive forces
stronger
cohesive forces
H2O
capillarity
Hg
The striking beauty of crystalline solids.
portion of a 3-D lattice
The crystal lattice and the unit cell.
lattice point
unit
cell
portion of a 2-D lattice
unit
cell
Phase Changes
Phase Changes
solid liquid gas
melting
freezing
vaporizing
condensing
sublimination
Energy absorbed
Energy released
Quick Review to what we have studied so
far.
Practicing science (Properties of foods)
Upcoming SlideShare
Loading in …5
×

Practicing science (Properties of foods)

998 views

Published on

The properties of foods which play very important role while discussing rheological and textural properties of foods.

Published in: Science
  • Be the first to comment

  • Be the first to like this

Practicing science (Properties of foods)

  1. 1. Prepared by :- Abhishek
  2. 2. Observing the Natural World of Matter What Is Matter? Matter is the material or “stuff” everything is made of. What are you doing if you are observing matter? Observing matter means to carefully explore all of its properties. Look around the room and identify some matter. What are some physical properties matter can have? Color, texture, odor, shape… What are two properties that all matter share? All matter has mass and takes up space. What are the three states of matter? solid, liquid, and gas
  3. 3. Solid, Liquid, Gas (a) Particles in solid (b) Particles in liquid (c) Particles in gas
  4. 4. Ice H2O(s) Ice Photograph of ice model Photograph of snowflakes
  5. 5. Liquid H2O(l) Water In a liquid • molecules are in constant motion • there are appreciable intermolecular forces • molecules are close together • Liquids are almost incompressible • Liquids do not fill the container
  6. 6. Gas H2O(g) Steam
  7. 7. Liquids The two key properties we need to describe are EVAPORATION and its opposite CONDENSATION add energy and break intermolecular bonds EVAPORATION release energy and form intermolecular bonds CONDENSATION
  8. 8. States of Matter Solid Liquid Gas Holds Shape Fixed Volume Shape of Container Free Surface Fixed Volume Shape of Container Volume of Container heat heat
  9. 9. Some Properties of Solids, Liquids, and Gases Property Solid Liquid Gas Shape Has definite shape Takes the shape of Takes the shape the container of its container Volume Has a definite volume Has a definite volume Fills the volume of the container Arrangement of Fixed, very close Random, close Random, far apart Particles Interactions between Very strong Strong Essentially none particles
  10. 10. • To evaporate, molecules must have sufficient energy to break IM forces. • Molecules at the surface break away and become gas. • Only those with enough KE escape. • Breaking IM forces requires energy. The process of evaporation is endothermic. • Evaporation is a cooling process. • It requires heat. Evaporation
  11. 11. Change from gas to liquid Achieves a dynamic equilibrium with vaporization in a closed system. What is a closed system? A closed system means matter can’t go in or out. (put a cork in it) What the heck is a “dynamic equilibrium?” Condensation
  12. 12. As time goes by the rate of vaporization remains constant but the rate of condensation increases because there are more molecules to condense. Equilibrium is reached when: Rate of Vaporization = Rate of Condensation Molecules are constantly changing phase “dynamic” The total amount of liquid and vapor remains constant “equilibrium” Dynamic Equilibrium
  13. 13. • Vaporization is an endothermic process - it requires heat. • Energy is required to overcome intermolecular forces • Responsible for cool earth • Why we sweat Vaporization
  14. 14. Energy Changes Accompanying Phase Changes Solid Liquid Gas Melting Freezing Deposition CondensationVaporization Sublimation Energyofsystem
  15. 15. Density & Specific gravity Density:-The density of a material is equal to its mass divided by its volume and has units of 𝑘𝑔𝑚−3 . It is of two types:-  Bulk Density  Particle Density What is porosity? Surface Gravity: SG = density of liquid / density of water
  16. 16. Viscosity Viscosity may be thought of as a liquid’s internal resistance to flow. A liquid can be envisaged as having a series of layers and when it flows over a surface, the uppermost layer flows fastest and drags the next layer along at a slightly lower velocity, and soon through the layers until the one next to the surface is stationary.
  17. 17. Van der Waals Forces and the Properties of Liquids • Viscosity increases with increasing intermolecular forces because increasing these forces increases the resistance to flow. – Other factors, such as the possibility of molecules tangling together, affect viscosity. – Liquids with long molecules that tangle together are expected to have high viscosities.
  18. 18. Continue… Pseudo plastic fluid – Viscosity decreases as the shear rate increases (e.g. emulsions, and suspensions such as concentrated fruit juices and puries) Dilatant fluid – Viscosity increases as the shear rate increases. (This behaviour is less common but is found with liquid chocolate and corn flour suspension.) Binghamor Casson plastic fluids – There is no flow until a critical shear stress is reached and then shear rate is either linear (Bingham type)or non-linear ( Casson type)(e.g. tomato ketchup) Thixotropic fluid – The structure breaks down and viscosity decreases with continued shear stress ( mostcreams) Rheopectic fluid – The structure builds up and viscosity increases with continued shear stress ( e.g.whippingcream)
  19. 19. Surface Tension • Surface tension is the tendency for liquid surface to contract. • Depends on attractive forces • Compounds that interfere with the forces and reduce surface tension are called surfactants.
  20. 20. Van der Waals Forces and the Properties of Liquids • Surface tension increases with increasing intermolecular forces. – Surface tension is the energy needed to reduce the surface area of a liquid. – To increase surface area, it is necessary to pull molecules apart against the intermolecular forces of attraction.
  21. 21. The molecular basis of surface tension. hydrogen bonding occurs in three dimensions hydrogen bonding occurs across the surface and below the surface the net vector for attractive forces is downward
  22. 22. Shape of water or mercury meniscus in glass. adhesive forces stronger cohesive forces H2O capillarity Hg
  23. 23. The striking beauty of crystalline solids.
  24. 24. portion of a 3-D lattice The crystal lattice and the unit cell. lattice point unit cell portion of a 2-D lattice unit cell
  25. 25. Phase Changes
  26. 26. Phase Changes solid liquid gas melting freezing vaporizing condensing sublimination Energy absorbed Energy released
  27. 27. Quick Review to what we have studied so far.

×