S1 Chapter 7 Science KPT (Diffusion & Osmosis) Flashcards
REFER TO NOTES GRAHHHHHHH
definition of diffusion
diffusion is the net (overall) movement of particles from a region of higher concentration to a region of lower concentration
1st factor that will affect the rate if diffusion (refer to notes too :D)
difference in concentration between the 2 regions.
The greater the concentration between 2 regions, the faster the rate of diffusion
when will diffusion stop?
diffusion will occur until the particles are evenly spaced out (STATE OF EQUILIBRIUM)
2nd factor that will affect rate of diffusion
temperature of solution /mixture
description (reason) for 2nd factor that affects rate of diffusion.
the speed of diffusion increases as the temperature increases because the particles have more kinetic energy at higher temperatures so they move faster.
the higher the temperature of the solution / mixture, the faster the rate of diffusion
3rd factor that affects the rate of diffusion
relative molecular (particle) mass of particles.
the smaller the relative molecular mass of the particles, the faster the rate of diffusion
4th factor that affects rate of diffusion
surface area to volume ratio (usually for cells)
example of diffusion occurring without a membrane
when a lump of sugar is dropped into a beaker of water, the sugar molecules dissolve and diffuse in the water, eventually, diffusion results in an even distribution of sugar molecules throughout the water
can diffusion occur without a membrane?
yes diffusion can occur with or without a membrane.
example + reasoning for 4th factor that affects rate of diffusion
a red blood cell is biconcave in shape. Being biconcave increases its surface area to volume ratio, so that gases can diffuse in and out of the cell faster. as the surface area to volume ratio increases, the rate of diffusion increases.
what are the 3 types of membranes and their meanings?
- permeable: allows all molecules to pass through (eg: cell wall)
- partially permeable: only allows particles smaller than its pore size to pass through (eg: visking tubing / cell membrane)
- impermeable: no molecules can pass through
example of diffusion occurring with a membrane
red blood cell. oxygen diffuses from lungs to red blood cells. haemoglobin
binds to the oxygen molecules reversibly. the oxygen is released and diffuses to tissue cells.
examples of molecules small enough to pass through the pores of the Visking tubing?
water, glucose, iodine molecules
what is a visking tubing?
a visking tubing is a type of partially permeable membrane that allows only small molecules to pass through
examples of molecules too large to pass through the pores of the Visking tubing?
starch and sucrose molecules
what is the definition of osmosis?
net movement of water molecules from a solution of higher water potential to a solution of lower water potential through a partially permeable membrane.
what is a dilute solution and its water potential?
small concentration of solute particles in a given volume of water / solvent. higher water potential compared to concentrated solution.
is osmosis a special case of diffusion?
yes
what are the conditions needed for osmosis? (refer to notes :DD)
- solutions of different water potential
- partially permeable membrane separating the solutions
can we use “water concentration” when talking about osmosis? if not, what should be used?
no. water potential.
what is a concentrated solution and its water potential?
a relatively large concentration of solute particles in a given volume of water / any other solvent. lower water potential compared to dilute solution.
what is the definition of water potential?
water potential is the tendency for water molecules to move from one region to another
how to answer questions for osmosis questions? (2)
- state direction of movement of water molecules
how to answer questions for osmosis questions? (1)
- compare water potential of solutions between 2 regions
how to answer questions for osmosis questions? (3)
state the process (osmosis) + via partially permeable membrane
how to answer questions for diffusion questions? (1)
- compare concentration between 2 regions
how to answer questions for osmosis questions? (4)
- state the effect if any, depending on the context of the question
how to answer questions for diffusion questions? (2)
- state direction of movement of particles
how to answer questions for diffusion questions? (3)
state the process (diffusion); can take place with / without membrane.
how to answer questions for diffusion questions? (4)
- state effect, if any
