Majal Abe B. Mirasol, Lou Serafin M. Lozada, Jainal-Rafi M. Ladja (March 2001)
Philippine Science High School Western Visayas Campus – Department of Science and Technology (DOST-PSHS WVC), Brgy. Bito-on, Jaro, Iloilo City 5000, Philippines
ABSTRACT
This study aimed to determine the feasibility of blackberry (Rubus sp.) as a pH level indicator (0-14). It also determined the significant differences in the different color wavelengths of the blackberry extract exposed to pH levels ranging from 0 to 14. The independent variable in this study was pH levels of 15 solutions, while the dependent variable was the color wavelength of the blackberry extract exposed to a certain pH level. The blackberry extract was added with NaOH to make the pH of the solution 7. Solution of different known pH levels from 0 to 14 were prepared and added with the extract. The color of the blackberry extract in each was determined using a spectrophotometer that measured the color wavelength in nanometers (nm).
In pH 0, the color wavelength was 575 nm. In pH 1, the color wavelength was 555 nm. In pH 2, the color wavelength was 525 nm. In pH 3, the color wavelength was 530 nm. In pH 4, the color wavelength was 526 nm. In pH 5, the color wavelength was 520 nm. In pH 6, the color wavelength was 527 nm. In pH 7, the color wavelength was 533 nm. In pH 8, the color wavelength was 525 nm. In pH 9, the color wavelength was 533 nm. In pH 10, the color wavelength was 525 nm. In pH 11, the color wavelength was 527 nm. In pH 12, the color wavelength was 529 nm. In pH 13, the color wavelength was 535 nm. In pH 14, the color wavelength was 530 nm.
The results showed that there was no significant difference in some parts of the spectrum. There are, however significant differences between pH levels 0 to 30 and 5 to 7.