Question

phase 2:
diffusion rate in water
complete the following steps:
1 add water to empty dish
2 add one crystal to dish with water using tweezers
3 wait 15 minutes
4 measure the diffusion spot diameter. record in lab data
5 calculate average diffusion rate from time zero in mm/h. record in lab data

Explanation:

Read the diffusion spot diameter

Using the Diffusion Measurement and Lab Data Recording knowledge points

• The purple diffusion circle spans across the ruler placed in the petri dish.
• The left edge of the purple circle aligns with the \(0\text{ cm}\) mark.
• The right edge of the purple circle aligns with the \(8\text{ cm}\) mark.
• Therefore, the diameter of the diffusion spot is:

$$ \text{Diameter} = 8\text{ cm} - 0\text{ cm} = 8\text{ cm} $$

• Converting centimeters to millimeters:

$$ 8\text{ cm} \times 10\text{ mm/cm} = 80\text{ mm} $$

Calculate the average diffusion rate

Using the Diffusion Rate Calculation knowledge point

• The elapsed time is given in Step 3 as \(15\text{ minutes}\).
• Convert the time from minutes to hours:

$$ \text{Time} = \frac{15\text{ min}}{60\text{ min/h}} = 0.25\text{ h} $$

• Calculate the average diffusion rate in \(\text{mm/h}\):

$$ \text{Diffusion Rate} = \frac{\text{Diameter}}{\text{Time}} = \frac{80\text{ mm}}{0.25\text{ h}} = 320\text{ mm/h} $$

Answer:

Question 4

The diffusion spot diameter is <blank>80</blank> \(\text{mm}\).

Question 5

The average diffusion rate from time zero is <blank>320</blank> \(\text{mm/h}\).