Student Misconceptions in Chemistry - Making Mountains out of Molehills

Happy National Chemistry Week and National Mole Day!

Every year, the American Chemical Society celebrates National Chemistry Week (October 18–24). In 2020, the theme of the program is “Sticking with Chemistry”, and educators and their students worldwide will be celebrating glues and adhesives. If you teach chemistry in your classroom, you may want to celebrate this week by creating your own glues or adhesives, comparing the strengths or properties of commercially available glues, evaluating the role of glues and adhesives in history and in the modern world, or exploring the impacts of their manufacture on our planet.

And of course, National Chemistry Week encompasses National Mole Day (23 October). But what is a mole, anyway? A mole is an amount used in stoichiometric calculations. Many students find the concept of the mole - an extremely large number - difficult to conceptualize. Given that the use of stoichiometry, which deals with the relationships between amounts of substances, is a key skill in chemistry, it is important that students understand the concept of a mole and its applications. But how can teachers make learning about moles straightforward, as well as interesting?

Related: Visualizing Chemistry Online: How animations of molecular-level events can improve student understanding of chemistry »

What is a mole, anyway?

For the purpose of this article, the mole (symbol: mol) is a SI unit and contains 6.022 × 1023 elementary entities (and hence Mole Day falls on 10/23). An analogy would be the term “dozen” - a catchall word that allows us to refer to a large number of entities easily. To give an idea of the immensity of this number of entities, for example - a mole of sand (in other words, 6.022 × 1023 grains of sand) packed densely into a cube would form a monolith nearly 17 kilometers high - many times higher than the world’s tallest building, the Burj Khalifa.

And of course, elementary entities, like molecules and atoms, vary in size. A mole of water differs in size and mass to a mole of hydrogen ions. For interest, a fun explanation of the mole concept and how it applies to different substances can be found on the Ted-ED blog.

So, accepting the definition given here, the concept of the mole appears to be rather simple. It’s a very large number - where could students go wrong? Unfortunately, the concept of the mole can be a tripping point for students in their chemistry journey.

Related: How to engage your science students in active, hands-on learning whether they are online or in the lab »

Moles and misconceptions

As the mole has been identified as a difficult idea for students to grasp, various studies have investigated mole-related misconceptions. Some common misunderstandings include that the mole refers to a certain mass rather than a number, and that different substances of equal mass are made up of the same number of moles. In addition, other learning issues may impact a student’s ability to understand the mole, with anxiety about mathematics being associated with poor achievement in chemistry.

Fortunately, as this conceptual problem has been well documented over the years, suggestions have been made for how to assess and improve student understanding. These suggestions include:

Introducing the Lt Chemistry Collection

As identified by the ACS, stoichiometry (and therefore the mole) is one of the key areas of the chemistry curriculum. In an effort to contribute to the education of our future chemists, ADInstruments and Vernier® Science Education have partnered to create the Lt Chemistry Collection, currently in development. The collection contains 19 General Chemistry labs that address a range of core concepts in the undergraduate chemistry curriculum. Labs within the Lt Chemistry Collection that involve stoichiometry include Acid-Base Titration, Standardizing a Solution, Identifying an Unknown Diprotic Acid, Conductimetric Titration and Gravimetric Determination of a Precipitate, Molar Volume of a Gas, and Determining a Chemical Formula.

17 of these 19 labs are designed to be used with Vernier’s suite of compact, affordable USB Go Direct® sensors. Students can record real-time data from their chemistry experiments into the Lt platform, then analyze their data and test their understanding through a range of interactive questions. For those students who are learning remotely, example data is provided, so they can discover and analyze the results of the experiments without needing to be on site.

The labs promote key skills recommended by the American Chemical Society, such as communication and critical thinking. The labs also equip students with practical lab skills, including the use of glassware, balances, and probeware, and the preparation of chemical solutions. Built-in lab reports support students to communicate their findings, and questions are created with Bloom’s taxonomy in mind, to promote diverse and rigorous assessment. Some labs include extensions that can be removed to accommodate for time or complexity requirements.

If you are looking to introduce your students to the mole concept in your practicals, consider this turnkey solution. Thanks for learning about the mole with us!

Happy National Chemistry Week!

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