Center for Power Optimization of Electro-thermal Systems

## What happened to the chemicals when they combined?

Student Sheet

### Estimated class Time:

One 40-minute class period

### Question:

What happened to the chemicals when they combined?

### Materials:

• Student sheets
• Colored pencils or crayons
• Manipulatives in four different colors(Skittles, M&M’s, pony beads, etc.)
• OPTIONAL: White boards and colored dry-erase markers

### Lesson Level Learning Objectives:

• MS PS 1-1: Develop and use models which show patterns that the total number of each type of atom is conserved in a chemical reaction/equation.

### Phenomenon:

Students first model a chemical equation using materials such as beads, M&Ms, Skittles, etc. The students will be told that this is the chemical equation for one of the bubbly reactions that they have done. A chemical equation is a short-hand way that uses symbols to tell what happens when substances interact.

CH3COOH + NaHCO3 -> CH3COONa + CO2 + H2O.

-Vinegar, Acetic acid (l) combines with baking soda, sodium bicarbonate (s) to form sodium acetate (aq), carbon dioxide (g) and water (l)

Students share out their models and the teacher creates a common noticings list.

• color association (key)

• chunking atoms together

• number of atoms in each molecule

• same number and type on each side, but rearranged into new substances

• two molecules are on one side and three molecules are on the other side

• plus signs

• arrow

Based on the noticings and discussion, students draw an updated model of the chemical equation. This model should address that there are the same number and type of atoms on each side of the equation. This is called conservation of mass.

### What we Figured Out:

• There are the same number and type of atoms on each side of the equation.
• In a chemical reaction the atoms get rearranged and form something new.
• Reactants → Products
• Element symbols always start with a capital letter and are one or two letters.
• Subscripts are the small numbers after an element symbol and tells how many atoms of that element there are.
• Coefficients are the large number in front of a molecule and tell how many molecules there are.
• In the anchoring phenomenon there are the same number and types of atoms in the reactants and the products.

### Questions we still have:

• What does this look like/how does it work in the real world?
• Does this work for all reactions?