Evidence of a Chemical Reaction NGSS MS-PS1-2

In the Evidence of a Chemical Reaction mini unit, students differentiate between physical and chemical changes and learn the signs of a chemical reaction while mixing baking soda and vinegar. Students share their evidence for a chemical change with a Claim, Evidence and Reasoning.

Extension activities challenge students to create a menu that describes the chemical and physical changes that occur while cooking a favorite dish or meal. Students love making connections between cooking and chemistry!

Anchor Phenomenon Ideas: There are many fun chemical reactions to choose from as an anchor. Mentos and Coke, elephant toothpaste or just large quantities of baking soda and vinegar are our favorites. Share one or more reactions with students and let the discussion begin! Use the questions your students come up with to make connections throughout your unit.

Make it Relevant: Once students see things "blow up" they are highly engaged! Use this opportunity to point out less explosive chemical reactions that we use everyday like burning fuel to drive a car, digesting proteins and fats with hydrochloric acid, baking cookies or rust forming on metal.

Tips and Tricks: Encourage students to be creative in their investigation design. Can they think of a way to collect the gas that forms? A balloon attached to a flask works well. Here is a detailed explanation of the chemical reaction taking place.

To write their claim, evidence and reasoning, students should have three pieces of evidence that a chemical reaction has taken place. Formation of a gas and a temperature change are easy to observe and students can cite the starting and ending temperatures as two separate pieces of evidence.

Enrichment Ideas: If students are curious about other chemical reactions, encourage them to design another investigation to find answers.

Does baking powder react with vinegar in the same way? Would lemon juice and baking soda create a chemical reaction too? What happens if you double the amount of baking soda but leave the amount of vinegar the same?