General chemistry students' conceptual understanding and language fluency: acid-base neutralization and conductometry

The objective of this study was to examine college general chemistry students' conceptual understanding and language fluency in the context of the topic of acids and bases. 115 students worked in groups of 2-4 to complete an activity on conductometry, where they were given a scenario in which a titration of sodium hydroxide solution and dilute hydrochloric acid was tracked by measuring electrical conductivity. Students were asked to write a balanced equation for the reaction, provide a particulate level drawing of the reactants and products, write a net ionic equation for the reaction, predict how electrical conductivity would change with the addition of sodium hydroxide to the acid, provide a sketch of their prediction, and explain their sketch. As students worked on the activity, conversations in their groups were audio recorded. Their written responses and audio conversations were analyzed to decipher conceptual understanding and language fluency. Results showed widespread lack of conceptual understanding as well as a lack of language fluency. Students struggled with very basic ideas regarding acid-base chemistry, such as identifying the right species involved in the neutralization reaction, and providing symbolic and sub-microscopic representations (an aspect of the language of chemistry) of the acid-base reaction. Most students could not accurately predict how electrical conductivity would change as the neutralization reaction progressed. None of the groups provided an accurate sketch depicting the trend of electrical conductivity. Most of the groups did not correctly apply acid-base neutralization ideas to the context of conductometry, indicating that students were not able to transfer knowledge of acid-base neutralization to this new context.