Controlling the Amount of Products in a Chemical Reaction

Learning Resource Type

Classroom Resource

Subject Area

Science

Grade(s)

8

Overview

In this lesson, students will analyze the chemical equation for the reaction between vinegar (acetic acid solution) and baking soda (sodium bicarbonate). They will make the connection between the written chemical equation, the molecular model, and the real substances in the reaction. Students will see that the gas produced in the actual reaction is also written in the products of the equation. Students will also change the amount of one or more reactants and see how the change affects the amount of products.

Students will be able to explain that for a chemical reaction to take place, the bonds between atoms in the reactants are broken, the atoms rearrange, and new bonds between the atoms are formed to make the products. Students will be able to count the number of atoms on the reactant side and on the product side of a chemical equation. They will also be able to explain that the equal number of atoms on each side of the equation shows that mass is conserved during a chemical reaction. Students will also be able to explain, on the molecular level, why changing the amount of one or more reactants changes the amount of products. They will also be able to explain why simply adding more and more of one reactant will eventually not produce additional products.

Science (2015) Grade(s): 8

SC15.8.6

Create a model, diagram, or digital simulation to describe conservation of mass in a chemical reaction and explain the resulting differences between products and reactants.

UP:SC15.8.6

Vocabulary

  • Conservation of mass
  • Chemical reaction
  • Product
  • Reactant
  • Model (e.g., diagram, digital simulation)

Knowledge

Students know:
  • Substances react chemically in characteristic ways.
  • In a chemical reaction, the atoms that make up the original substances (reactants) are regrouped into different molecules, and these new substances (products) have different properties from those of the original substances (reactants).
  • In a chemical reaction, the total number of each type of atom is conserved, and the mass does not change. In a chemical reaction, each molecule in each of the reactants is made up of the same type(s) and number of atoms.
  • In a chemical reaction, the number and types of atoms that make up the products are equal to the number and types of atoms that make up the reactants.
  • Each type of atom has a specific mass, which is the same for all atoms of that type.

Skills

Students are able to:
  • Develop a model, diagram, or digital simulation in which they identify the relevant components for a given chemical reaction.
  • Describe relationships between the components.
  • Use the model to describe that the atoms that make up the reactants rearrange and come together in different arrangements to form the products of a reaction.
  • Use the model to provide a causal account that mass is conserved during chemical reactions because the number and types of atoms that are in the reactants equal the number and types of atoms that are in the products, and all atoms of the same type have the same mass regardless of the molecule in which they are found.

Understanding

Students understand that:
  • In a chemical reaction, the atoms of the reactants are regrouped into different molecules, and these products have different properties from those of the original reactants.
  • Mass is conserved during chemical reactions and the mass of reactants is equal to the mass of the products.

Scientific and Engineering Practices

Developing and Using Models

Crosscutting Concepts

Energy and Matter

CR Resource Type

Lesson/Unit Plan

Resource Provider

American Chemical Society

License Type

Custom

Accessibility

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