Discrepant Event: Synthesis of Magnesium Oxide
Purpose:
To demonstrate a synthesis/combination chemical reaction. To get the students to predict
the products of a chemical reaction. Visually demonstrate a chemical reaction for the
students. Practice lab safety and gain the interest of the students.
Grade Level:
- Grade 11 Applied Chemistry
- Applies to all grade levels of Chemistry
Ontario Curriculum:
- This discrepant event fits nicely into the Grade 11 University Preparation
Chemistry course under the strand Matter and Chemical Bonding.
-
More specifically this is outlined under the Understanding Basics Concepts
heading on page 46 of the Ontario Grade 11 and 12 Science Curriculum
Document. The expectation is that students will, “demonstrate an understanding
of the relationship between the type of chemical reaction (e.g. Synthesis,
decomposition, single and double displacement) and the nature of the reactants.
Theory:
A combination or synthesis reaction is a chemical reaction where 2 or more substances
combine to form a single product.
The general equation for a combination reaction is:
A + B  AB
Reaction:
2 Mg(s) + 02(g)  2 MgO(s)
Materials:
- 3cm piece of Magnesium ribbon
- Beaker tongs
- Bunsen burner and hose
- Flint
- Goggles and lab coat
Procedure:
- cut or bend and break off a 3cm piece of Magnesium ribbon from the role
- light a Bunsen burner and adjust the flame
- hold the piece of Magnesium ribbon with a set of Beaker tongs and hold the piece
of Magnesium ribbon in the flame
- DO NOT LOOK DIRECTLY AT THE FLAME PRODUCED
- Show the class the white precipitate formed in the reaction
Hints for Success:
- Try to get the students to predict the products of the chemical reaction
- Explain or get the students to explain what type of chemical reaction took place
- Generally a 3-4cm piece of magnesium ribbon is all that is required
Safety:
- wear your lab goggles and lab coat
- do not look directly at the flame produced in the chemical reaction because it
will damage the retina of your eye
References:
Jenkins, Frank. 2002. Nelson Chemistry 11. Nelson-Thomson Learning. Canada.
Ontario Curriculum Document for Grades 11 and 12 Science (page 46).