## Energy Changes Objectives

We are just starting on the Energy Changes unit. Here is a summary of what you are responsible for in this unit:

 # Objective Must-do Activities Videos 1 Produces an energy diagram representing the energy balance for a chemical reaction Energy Diagram assignment, Energy Test #1 Energy Diagrams, Reversible Reactions 2 Interprets the energy diagram of a chemical reaction Energy Diagram assignment, Energy Test #1 Energy Diagrams, Reversible Reactions 3 Explains qualitatively the enthalpy change of substances during a chemical reaction Energy Test #1 Heat Transfer, Enthalpy, Energy Diagrams 4 Determines the molar heat of a reaction using a calorimeter Molar Heat assignment, Energy Test #1 Heat Transfer, Molar Heat,  Neutralization, Stoichiometry 5 Determines the molar heat of a reaction using Hess’s Law Hess’s Law assignment, Energy Test #2 Hess’s Law 6 Determines the molar heat of a reaction using bond enthalpes Bond Enthalpies assignment, Energy Test #2 Bonding Enthalpies

## Yeast lab

Here is the chemical equation that represents the breakdown of sugar:

$C_{12}H_{22}O_{11(s)} + H_2O_{(l)} \rightarrow 4CO_{2(g)} + 4C_2H_5OH_{(l)}$

For this lab, you will compare experimental and theoretical results for how much carbon dioxide (CO2) is produced when sugar (C12H22O11) is broken down in water (H20), using yeast as a catalyst.

Materials:

• 4 packets of quick rise yeast (we will use 2 packets but it is good to have extra on hand just in case)
• a small soda or water bottle (500 mL)
• 1/4 cup of white sugar (we will use 1 tsp = 5 mL, but it is good to have extra on hand just in case)
• 3 balloons (we will use 1 balloon, but it is good to have extra on hand just in case)
• 1 meter of string
• 1 teaspoon measuring spoon
• a balance for measuring mass (optional)
• a meter stick

The rest of the instructions are in Sakai Resources > Classwork > Gases.