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
