Background InformationThe mole concept is the foundation of the unit and the course going forward. Without a firm understanding of the basic tenant student will struggle with more advanced chemistry. Moles link the substances in chemical formulas and equations to actual amounts needed in practice. The mole concept has been around for 60 years but is still the subject of debate amongst chemists. It has multiple meanings, is very abstract and full understanding requires students to have developed the formal operational stage of thinking (Piaget). As a result most students will struggle with this concept and may not fully understand it well into university. The mathematical portion requires students to have some skill in algebra but most can do the math without any depth of understanding. Learning the mole concept is essential to the SCH 3U1 course and for any further study in chemistry.

Overall Expectations

D3. demonstrate an understanding of the mole concept and its significance to the quantitative analysis of chemical reactions

Specific Expectations

D2.1 use appropriate terminology related to quantities in chemical reactions, including, but not limited to: stoichiometry, percentage yield, limiting reagent, mole, and atomic mass [C]D2.2 conduct an inquiry to calculate the percentage composition of a compound (e.g., a hydrate) [PR, AI]D2.3 solve problems related to quantities in chemical reactions by performing calculations involving quantities in moles, number of particles, and atomic mass [AI]D2.4 determine the empirical formulae and molecular formulae of various chemical com- pounds, given molar masses and percentage composition or mass data [AI]D2.5 calculate the corresponding mass, or quantity in moles or molecules, for any given reactant or product in a balanced chemical equation as well as for any other reactant or product in the chemical reaction [AI]D3.2 describe the relationships between Avogadro’s number, the mole concept, and the molar mass of any given substanceD3.4 explain the quantitative relationships ex- pressed in a balanced chemical equation, using appropriate units of measure (e.g., moles, grams, atoms, ions, molecules)

Concept Map

Difficulties/ Misconceptions

Key Difficulty #1Chemists do not agree on how the ”mole” should be defined

The word "mole" has acquired three meanings: · an individual unit of mass;· a portion of substance; · and a number

Strategies1. Show students elements in a whole-number mass ratioEx. Show Copper (M= 64) and Sulphur(M=32). Ratio is 2:12. Show that the ratio remains fixed, regardless of the number of atomsEx. Inquire as the ratio of 10 each or 1 million each

3. Introduce the masses in grammes which chemists use: ask about the number of atoms present Use 2 beakers, one mole of each element with mass labeled.Key Difficulty #2The mole is taught as an abstract mathematical idea

The mole is often taught in a mathematical way causing the chemical meaning to be obscured. Students who struggle to manipulate numbers and symbols will find this approach towards learning the mole very difficult to understand

Strategies1. Leave math until the last possible moment.2. Scaffold with equation triangles for both equations and show how they are connected via the mole 3. Gradual release. Model, group, tutor pairs, individual.

Key Difficulty #3Students lack secure understanding of preliminary concepts

The mole is an idea which connects basic principles about chemical reactions to the more advanced concepts involving controlling reactions.

Strategies1. Formula CardsEx.Elements with combining capacity of 1 are square, of 2 are twice the length, and 3 are triple length, 4 etc...2. Traffic lights for every studentEx. Red if student doesn't understand, green if they are following along. Stop periodically to get signal.3. Exit slipsHandy Assessment tool for the end of lesson

Key Difficulty #4Avogadro’s number cannot be ”seen”

The size of Avogadro’s number is too large to be readily comprehended

Strategies

1. Students can be given an impression of its size by the use of powerful visual images.Ex. One mole of sand grains stretching for one mile (1.6km); or One mole of marbles foming a layer 1500 km deep over the UK and Ireland.2. Students can make the connection from the microscopic to macroscopic using molar quantities of familiar elementsEx. Demo for students 1 mole of various element and compounds

Reinforce the concept that a mole is an amount of substance

Advanced Prep- Laptop and Projector with a Smartboard- Formula Cards- Beakers- Chart paper/ whiteboards- Copper- Water- Sulphur- Salt- Molecular Model Kits- Handouts

SafetyEnsure normal safety procedures are followed at all times in a lab. Care should be given to handling sulphur and ensure that it is in a sealed container. Sulphur dust can affect students with asthema.

Societal ImplicationsResearch: Impossible to do without practical quantities on a large scaleIndustry: Ability to go from microscopic to macroscopic allows products to mass produced with equal ratios of starting material.

References

1. Kind, V., Beyond appearances: students’ misconceptions about basic chemical ideas, 2004. 2nd edition

2. Howe, Ann C., The Mole Concept: Developing an Instrument To Assess Conceptual Understanding, Journal of Chemical Education,1994: 653- 655

3. TES Connect website: http://www.tes.co.uk/resourcesHome.aspx?navcode=70

4. Dr. Frank Jenkins, Hans van Kessel, Dick Tompkins, Oliver Lantz, Lucille Davies, Patricia Thomas,. Chemistry 11 Textbook, Nelson, 2002

5. http://www.ulster.ac.uk/scienceinsociety/molepack.html