Unit 6: investigation project.
Part A.
Experiment: the effect of changing the surface area of the agar jelly on diffusion.
Why have I chosen this topic?
I have chosen to do a diffusion practical by changing the surface area of agar jelly as it shows how
diffusion works in molecules that are not part of the body. I have always been fascinated by diffusion
in gases due to my experiences with it in everyday life. For example, spraying a perfume or cooking
dinner has a process of diffusion in it. If a person sprays a perfume, then after a minute, then a
person at the back of a room would also be able to smell the perfume, due to diffusion. Similarly, if
someone is cooking something, after a few minutes, the smell of the food would diffuse around the
room, and you would be able to smell it. The smell from the perfume and the food travels around as
the particles would diffuse. Also, the particles are free flowing and move in a random motion, which
makes the process diffusion. Also, doing similar diffusion experiments makes me want to do a
diffusion experiment but this time, changing another factor, to see how diffusion would work when
another factor that has been changed.
What is diffusion?
Diffusion is a type of transport, and it is the overall passive movement of molecules move from an
area of high concentration to an area of low concertation, without using any energy. This is due to
the random motion of particles. For example, diffusion happens in the body’s intestines, calcium
from the intestines would diffuse into the normal body cells so that they can function. This is done
by the diffusion process. A concentration gradient occurs during diffusion as the molecules have to
go from where there are lots of particles to where there are less particles. Diffusion is passive
transport as energy isn’t needed for the molecules to diffuse. This is because diffusion happens in a
liquid and a gas, where the particles are free moving. The particles move in a random motion
whereas in solids, the particles are fixed, so diffusion can’t take place. Diffusion doesn’t require a
transport protein to transport the molecules down the concentration gradient. Diffusion stops when
the molecules on either side of the concentration gradient have roughly equal number of molecules
on each side. This is called dynamic equilibrium. Diffusion would stop until dynamic equilibrium is
achieved. Diffusion rate can happen faster and slower due to factors that affect it, but it can also
happen if the concentration gradient is stronger. The stronger the concentration gradient, the faster
diffusion would take place. There are two types of diffusion. One of them is simple diffusion and the
other is facilitated diffusion. Simple diffusion is when particles travel through a semi permeable
membrane, and they don’t need to use transport proteins to do so. Facilitated diffusion needs to use
transport molecules or carrier molecules for diffusion to occur. Both types of diffusion do not need
energy for the movement of the molecules. This research is relevant to this investigation as it helps
me to understand diffusion better and what happens when I am doing my experiment. All the
information that I have included and researched about is relevant for me as it helps me frame the
proposal for the experiment and know how my factor that I am changing would affect diffusion
properly. Researching the factors that affect diffusion also helps me to understand my experiment
better and helps me to make a hypothesis and a proposal for the experiment that I am going to carry
out. The websites that I have used to help me research and find out about diffusion are all valid and
authentic, so I had easily gotten the information. I avoided websites like Wikipedia, as these
websites are not valid not authentic as people can easily edit them. This means that the information
1
, isn't reliable to use, then researching for a proposal for the experiment. Using information that isn't
authentic can make the hypothesis wrong.
Factors that affect diffusion.
Temperature.
Temperature is a factor that can affect how fast diffusion can happen.
When the temperature in a gas or a liquid is higher, diffusion would occur
at a faster rate. This is because the molecules or the ions in a gas or liquid
would gain more kinetic energy. The more kinetic energy the molecules or
the ions have, the faster the rate of diffusion happens. Having more kinetic
energy would mean that the molecules would move across the semi
permeable membrane at a faster rate.
The difference in concentration.
If the concentration gradient is greater, diffusion would take place at a faster rate. If on
one side of the equilibrium has more molecules than the other side, the particles can easily
diffuse across the membrane until the equilibrium is reached, and both sides of the
membrane have roughly the same number of molecules in it. If there are roughly the same
number of particles on either side of the equilibrium, then the concentration gradient is
lesser. This means that the diffusion rate would be slower as less molecules need to diffuse
across until the optimum equilibrium is reached.
Diffusion medium.
Different mediums affect the rate of diffusion. In a solid, the
particles are tightly packed together, meaning that the particles
can’t move due to the lack of space it has. This is because the
particles can’t flow or move, meaning that diffusion can't take
place as the particles need to move in order for diffusion to occur. In a liquid, the particles can move
more compared to a solid. The particles in a liquid are free flowing meaning that diffusion can take
place. In a gas, the particles move in random motion, meaning that diffusion can take place.
Diffusion works best in a gas due to the arrangement of the particles and how free flowing the
molecules are. If the molecules have more space to move, then diffusion would take place better.
The distance the molecules have to travel.
The distance a molecule has to travel would determine how fast the
rate of diffusion would be. If the distance that the molecules have to
diffuse across is larger, the slower the diffusion rate would be. This is
because the molecules have to travel a longer distance in order to
diffuse across to the other side of the membrane. If the diffusion
distance to the membrane is shorter, the molecules can quickly and
easily diffuse across the membrane. this means that the rate of diffusion would be faster.
Size of the particle.
If the particles that are diffusing across the membrane are smaller, they
would diffuse faster. This is because the smaller the particles, the faster they
move. Also, if the membrane pores are small, then smaller particles would be
able to easily diffuse across it compared to larger particles that can't pass
2
Part A.
Experiment: the effect of changing the surface area of the agar jelly on diffusion.
Why have I chosen this topic?
I have chosen to do a diffusion practical by changing the surface area of agar jelly as it shows how
diffusion works in molecules that are not part of the body. I have always been fascinated by diffusion
in gases due to my experiences with it in everyday life. For example, spraying a perfume or cooking
dinner has a process of diffusion in it. If a person sprays a perfume, then after a minute, then a
person at the back of a room would also be able to smell the perfume, due to diffusion. Similarly, if
someone is cooking something, after a few minutes, the smell of the food would diffuse around the
room, and you would be able to smell it. The smell from the perfume and the food travels around as
the particles would diffuse. Also, the particles are free flowing and move in a random motion, which
makes the process diffusion. Also, doing similar diffusion experiments makes me want to do a
diffusion experiment but this time, changing another factor, to see how diffusion would work when
another factor that has been changed.
What is diffusion?
Diffusion is a type of transport, and it is the overall passive movement of molecules move from an
area of high concentration to an area of low concertation, without using any energy. This is due to
the random motion of particles. For example, diffusion happens in the body’s intestines, calcium
from the intestines would diffuse into the normal body cells so that they can function. This is done
by the diffusion process. A concentration gradient occurs during diffusion as the molecules have to
go from where there are lots of particles to where there are less particles. Diffusion is passive
transport as energy isn’t needed for the molecules to diffuse. This is because diffusion happens in a
liquid and a gas, where the particles are free moving. The particles move in a random motion
whereas in solids, the particles are fixed, so diffusion can’t take place. Diffusion doesn’t require a
transport protein to transport the molecules down the concentration gradient. Diffusion stops when
the molecules on either side of the concentration gradient have roughly equal number of molecules
on each side. This is called dynamic equilibrium. Diffusion would stop until dynamic equilibrium is
achieved. Diffusion rate can happen faster and slower due to factors that affect it, but it can also
happen if the concentration gradient is stronger. The stronger the concentration gradient, the faster
diffusion would take place. There are two types of diffusion. One of them is simple diffusion and the
other is facilitated diffusion. Simple diffusion is when particles travel through a semi permeable
membrane, and they don’t need to use transport proteins to do so. Facilitated diffusion needs to use
transport molecules or carrier molecules for diffusion to occur. Both types of diffusion do not need
energy for the movement of the molecules. This research is relevant to this investigation as it helps
me to understand diffusion better and what happens when I am doing my experiment. All the
information that I have included and researched about is relevant for me as it helps me frame the
proposal for the experiment and know how my factor that I am changing would affect diffusion
properly. Researching the factors that affect diffusion also helps me to understand my experiment
better and helps me to make a hypothesis and a proposal for the experiment that I am going to carry
out. The websites that I have used to help me research and find out about diffusion are all valid and
authentic, so I had easily gotten the information. I avoided websites like Wikipedia, as these
websites are not valid not authentic as people can easily edit them. This means that the information
1
, isn't reliable to use, then researching for a proposal for the experiment. Using information that isn't
authentic can make the hypothesis wrong.
Factors that affect diffusion.
Temperature.
Temperature is a factor that can affect how fast diffusion can happen.
When the temperature in a gas or a liquid is higher, diffusion would occur
at a faster rate. This is because the molecules or the ions in a gas or liquid
would gain more kinetic energy. The more kinetic energy the molecules or
the ions have, the faster the rate of diffusion happens. Having more kinetic
energy would mean that the molecules would move across the semi
permeable membrane at a faster rate.
The difference in concentration.
If the concentration gradient is greater, diffusion would take place at a faster rate. If on
one side of the equilibrium has more molecules than the other side, the particles can easily
diffuse across the membrane until the equilibrium is reached, and both sides of the
membrane have roughly the same number of molecules in it. If there are roughly the same
number of particles on either side of the equilibrium, then the concentration gradient is
lesser. This means that the diffusion rate would be slower as less molecules need to diffuse
across until the optimum equilibrium is reached.
Diffusion medium.
Different mediums affect the rate of diffusion. In a solid, the
particles are tightly packed together, meaning that the particles
can’t move due to the lack of space it has. This is because the
particles can’t flow or move, meaning that diffusion can't take
place as the particles need to move in order for diffusion to occur. In a liquid, the particles can move
more compared to a solid. The particles in a liquid are free flowing meaning that diffusion can take
place. In a gas, the particles move in random motion, meaning that diffusion can take place.
Diffusion works best in a gas due to the arrangement of the particles and how free flowing the
molecules are. If the molecules have more space to move, then diffusion would take place better.
The distance the molecules have to travel.
The distance a molecule has to travel would determine how fast the
rate of diffusion would be. If the distance that the molecules have to
diffuse across is larger, the slower the diffusion rate would be. This is
because the molecules have to travel a longer distance in order to
diffuse across to the other side of the membrane. If the diffusion
distance to the membrane is shorter, the molecules can quickly and
easily diffuse across the membrane. this means that the rate of diffusion would be faster.
Size of the particle.
If the particles that are diffusing across the membrane are smaller, they
would diffuse faster. This is because the smaller the particles, the faster they
move. Also, if the membrane pores are small, then smaller particles would be
able to easily diffuse across it compared to larger particles that can't pass
2
