Unit 3- MRS CONNOLY'S WORK

Kinetic Theory:

What is the particle arrangement, movement and relative energy of a solid, liquid and gas.

Solid:

• PA- regular fixed arrangement

• PM- Vibrates about, fixed position

• RE- Low

Liquid:

• PA- irregular

• PM- freely over each other

• RE- intermediate

Gas:

• PA- irregular

• PM- constant random motion

• RE- high

Kinetic Theory:

What is diffusion?

Diffusion is the net movement of particles from an area of a high conc to an area of a low conc

Kinetic Theory:

Describe the process of diffusion

• Diffusion is a passive process

• It does not require energy input for the process

• Particles move down the conc gradient

• Eventually a dynamic equilibrium is reached which means stables concs, but particles are still moving

What are the factors affecting the rate of diffusion

1. SA to vol ratio (As an object gets bigger, the SA : VOL ratio gets smaller

2. Temp

3. Molecule size

4. Conc gradient

How does temp link to kinetic energy?

• The higher the temp, the more KE the particles will have

• So, the faster they will move

Diffusion Practical-

“Investigate how the different concentrations of HCL affects sodium hydroxide and phenolphthalein agar. Measure how long it takes for the squares to turn clear”

1. Use a ruler to cut agar into equal cubes of 1cm3

2. Prepare different concs of HCL such as 0.5M, 1.0M and 1.5M

3. Place one agar cube into a beaker containing a known conc of HCL + start stopwatch immediately

4. Observe the agar cube + record the time taken for it to turn completely colourless

5. Repeat experiment 3 times for each conc of HCL and calculate a mean time

Diffusion Practical-

“Investigate how molecule size affects the rate of diffusion through agar”

1. Using a straw cut two identical wells in the centre of the agar plate,

2. Carefully use a sterile spatula to remove the agar plugs from each well, ensure that the bottom of each well is completely clean

3. Using a pipette, add an equal measured volume (e.g. 2 cm³) of methylene blue solution into one well.

4. Using a separate pipette, add the same volume (e.g. 2 cm³) of potassium permanganate solution into the second well + place transparent ruler under petri dish

5. Start the stopwatch and leave the agar plate to stand undisturbed at room temperature on a flat surface for a fixed time period (e.g. 10 minutes).

6. After the set time, measure the distance of diffusion from the edge of each well to the outer edge of the coloured diffusion zone using a ruler in millimetres.

7. Record all results accurately and ensure all equipment is cleaned after use to maintain safety and reliability.