Single answerDifficulty 2/5 · StandardRepresenting dataArgumentation
Pink agar cubes
A class made agar containing phenolphthalein, which is colourless in neutral agar and turns pink wherever sodium hydroxide reaches. They cut cubes with sides of 0.5, 1, 2 and 3 cm, soaked them in 0.1 M NaOH for 10 minutes, then cut each cube in half and measured how far the pink colour had spread in from the surface.
Experimental setup
- Question
- How does the size of a cube affect how much of its volume a substance reaches by diffusion?
- Independent variable
- Side length of the cube (cm)
- Dependent variable
- Percentage of the cube's volume coloured pink
- Kept constant
- NaOH concentration (0.1 M) · Soaking time (10 min) · Temperature · Same batch of agar
- Groups
- Cubes: Side lengths 0.5, 1, 2 and 3 cm
Data
| Side (cm) | Surface area (cm²) | Volume (cm³) | SA:V (cm⁻¹) | Depth of pink (cm) | Volume coloured (%) |
|---|---|---|---|---|---|
| 0.5 | 1.5 | 0.125 | 12 | 0.25 | 100 |
| 1 | 6 | 1 | 6 | 0.25 | 87.5 |
| 2 | 24 | 8 | 3 | 0.25 | 57.8 |
| 3 | 54 | 27 | 2 | 0.25 | 42.1 |
Which conclusion do these data best support?
Answer every part to submit.