Question

Hypothesis: If you can measure the pH of a range of acids and bases using a universal pH indicator, then you can use those values to calibrate a cabbage pH indicator.

Which method helped you prove this hypothesis? Check all that apply.

Using various concentrations of HCl and NaOH to measure a range of pH

Using an existing scale to determine pH

Knowing that the cabbage indicator always has the same color at a given pH value

Answer 1

All three.

- Using various concentrations of HCl and NaOH gave you solutions spanning the pH range so you could observe different colors.
- Using an existing pH scale/indicator let you assign reliable pH values to those solutions.
- Confirming the cabbage indicator gives a consistent color at a given pH is necessary so you can map (calibrate) color → pH.