# Stoichiometry - Creating A Fizzy Drink

**Subject:** Chemistry

**Time:** 16 days (days are based on 50 min period length)

**Level:**

High School Honors Chemistry

## Unit Overview

This unit is not arranged as a traditional stoichiometry unit. Rather than beginning by stating the law of conservation of mass to students, it begins with an inquiry lab for students to discover that law. All quantities in this lab will be measured in grams. This will lead to a discussion of grams versus moles -- when each unit is appropriate and why. After students have developed this basic understanding, they will be presented with an in-class lab demonstration and subsequent simulation involving limiting reactants. Limiting reactants will be used to help students understand the most efficient ratios needed in a chemical equation that will produce maximum product. Students use this same logic and apply it in order to balance chemical equations. After they have mastered balancing, they will be presented with a challenge to solve several multi-step dimensional analysis problems. Then they will apply this same method and their knowledge of grams, moles, and balancing equations in order to solve stoichiometry problems.

The pre-assessment should be completed before beginning lesson 1.

This unit consists of 10 lessons overall. Lessons range from 50-100 minutes in length.

Lesson | Topic | Length |

1 | Introduction to the Phenomenon | 50 minutes |

2 | Inquiry Lab - Discovering the Law of Conservation of Mass | 100 minutes |

3 | Grams vs. Moles | |

4 | Limiting Reagents Dictate Molar Relationships (Simulation) | 100 minutes |

5 | Introduction to Balancing Chemical Equations (Simulation) | 100 minutes |

6 | Balancing Chemical Equations Practice | |

7 | Cookie Stoichiometry - Solving Multi-step Dimensional Analysis Problems | |

8 | Stoichiometry Practice | |

9 | Evaluating Stoichiometry Problems | |

10 | Lab Practical - Creating a Fizzy Drink |

Lesson 1: Introduction to the Phenomenon

Students are asked to create a carbonated beverage (fizzy drink) without the aid of an at home soda maker such as a SodaStream. Is this possible using chemicals that are safe to consume and would not affect the overall taste of the beverage other than imparting it with carbonation?

Lesson 2: Discovering the Law of Conservation of Mass

## Lessons Overview

Students are introduced to the phenomenon. First they will view a SodaStream advertisement, then they will be asked to brainstorm what a makes a fizzy drink fizzy. The phenomenon introduction closes with a teacher demonstration where a carbonated beverage is produced before their eyes without the aid of a SodaStream.

Students will perform two different experiments where they are asked to record the overall mass of the reactants and products before and after the reactions takes place. Both experiments will be "closed system" experiments where any gases produced will be trapped by either parafilm or a balloon. Students should observe that overall mass should remain the same before and after each experiment leading them to the law of conservation of mass. This proves that a carbonated beverage can be produced via a chemical reaction.

Students are introduced to the concept of the mole with a simple reading.

In this lesson students will review all quantitative measurement units used in chemistry they have learned thus far in order to compare and contrast microscopic units and macroscopic units. They should come to the conclusion that both moles and grams are macroscopic units while atoms and molecules are microscopic units. They will end by converting between macroscopic units of grams and moles.

In this lesson, students will observe a double displacement reaction where varying amounts of each reactant are used. They will be asked to focus on the amount of one product in the reaction and how the amount of that product changes relative to the amounts of each reactant used. The goal of the lesson is for students to understand the molar relationships in a reaction and why adding coefficients to a reaction is sometimes necessary.

This activity can be completed using the online simulation, molecular model kits in the classroom, or a combination of both. The interface on the website follows the online simulation and a handout is attached if you prefer to use molecular model kits in the classroom. I would recommend allowing students a choice between the two after they are allowed 10-15 min to explore both options.

This lesson is an activity using molecular model kits to balance chemical reactions. Students will build reactants, then disassemble the reactants to build products. Students are also asked to draw models of the overall balanced reactions on their handouts.

A simple introduction to molarity.

Full Stoich

This lesson serves as an introduction to multi-step dimensional analysis, particularly when and why it is necessary. Students will be converting a chocolate chip cookie recipe that is entirely in moles to standard cookie measurements (cups, teaspoons, etc.). In order to complete the conversions, students must start with the moles of their ingredient given in the overall chemical reaction. Then they will use the formula provided for their ingredient (the chemical formulas of the ingredients have been simplified) to find the molar mass and convert from moles to grams. The final step is using the calculated grams to convert to the final baking measurement using the conversions provided.

This lesson shows many of the common mistakes that students make when setting up and solving stoichiometry problems. Students are presented with multi-step stoichiometry problems that have already been completed and solved by "another student". They are asked to use a rubric to evaluate both the set-up and the answer, correct any problems with the set-up, and finally to recalculate the answer to solve the problem.

This lab practical is one of the final assessments for this unit. Students are asked to determine the correct stoichiometric proportions of baking soda and citric acid needs to carbonate ordinary Kool-Aid. They will be assessed both on their calculations and the overall taste of the final drink they make.

## Compatible With

mac

windows

laptops

chrome books

phones

tablets

## What's Next?

## Standards

**Next Generation Science Standards**

- Physical Science
- [HS-PS1 ] Matter and its Interactions
- NGSS Crosscutting Concept
- Energy
- NGSS Practice
- Using Mathematics

**Computational Thinking in STEM**

- Modeling and Simulation Practices
- Assessing Computational Models
- Using Computational Models to Understand a Concept
- Systems Thinking Practices
- Defining Systems and Managing Complexity
- Thinking in Levels
- Understanding the Relationships within a System
- Data Practices
- Analyzing Data

## Comments, Feedback, and Questions