Students’ misconceptions of acid-base titration assessments using a two - tier multiple-choice diagnostic test

Abstract

The paper portrays students' misconceptions of acid-base titrations using  two a tier diagnostic test. The analysis will inform chemistry teaching and learning, especially about acid-base concepts. The data were collected  through a two-tier diagnostic test with 10 stratified multiple choice questions that have been analysed for item validity (rphi = 0,415) and construct validity (V = 0,98) which show that it a valid instrument. Open questions were administered to explore students’ misconceptions. The results showed that 33.50% of students held misconceptions of acid-base titrations in the curriculum. The highest percentage of misconceptions were on acid-base titration indicators, with 40,42% students being more familiar with  phenolphthalein for NaOH and HCl titrations than with bromothymol blue. This misconception is sourced from chemistry teaching due to limited understanding of acid-base concepts and the lack of titration practicum in the laboratory with various indicators and types of titration. The lowest percentage of students’ misconceptions at the endpoint of the titration was 11.25% of the students having a good understanding of the endpoint of the titration although some students still have difficulty in distinguishing between the endpoints of a titration and the equivalent point. The results show that the students should have deep understanding of acid-base reactions before learning acid-base titrations.