74 Days Until the Final

1. What does the Latin root exo- mean?

2. What does the Latin root endo- mean?

End

Today’s Learning Targets 7.1 – I can describe how the motion of

molecules relates to temperature. For example, if I have a hot solution and a cold solution, I can explain the motion in the molecules in each one of these solutions.

7.2 – I can compare and contrast the ideas of an exothermic reaction and an endothermic reaction.

Today’s Focus Question

Does the breakdown of Flamin’ Hot Cheetos require energy or release energy?

Review of Heat and Temperature Heat is the transfer of energy between

substances due to a difference in temperature

The faster a substance is moving the higher its temperature will be.

A substance at a high temperature has fast moving molecules and a substance at a low temperature has slow moving molecules

Exothermic Reactions A reaction that releases

energy during the reaction is known as an exothermic reaction.

Energy often given off in the form of heat

Energy listed as a product in the equation

Reactants Products + Energy

Endothermic Reactions

A reaction that requires energy during the reaction is known as an endothermic reaction.

Energy often absorbed in the form of heat, so the substance feels cold

Energy listed as a reactant in the equation

Energy + Reactants Products

Phase Changes are Exo- and Endothermic!

Absorbs Energy

Phase Changes are Exo- and Endothermic!

Release Energy

Class Example Is the following reaction endothermic or

exothermic?

NH4NO3 + 453 kJ/mol HNO3 + NH3

Table Talk Is the following reaction endo- or

exothermic?

2H2 + O2 → 2H2O + 484 kJ/mol

Table Talk I have a pot of water and I heat it up until it

turns into gas. Is this an endothermic or exothermic process?

Stop and Jot You have a test tube where you run the

reaction. If the test tube is hot following the reaction, then is this endothermic or exothermic?

The Breakdown of Cheetos in Our Bodies

Before we can use food it needs to be converted to glucose.

Glucose is the only usable form that we humans can use to make ATP.

C6H12O6 (aq) + 6O2 (g) → 6CO2 (g) + 6H2O (l) + 2880 kJ/mol

Summarize

Work TimeComplete the worksheet with

your table.

Exit Slip Elephant Toothpaste Chemistry: Ever wanted to

make elephant toothpaste?

The overall equation for this reaction is:

2 H2O2(aq) --> 2 H2O(l) + O2(g) + 4080 kJ/mol

However, the decomposition of the hydrogen peroxide into water and oxygen is catalzyed by the iodide ion.

H2O2(aq) + I-(aq) --> OI-(aq) + H2O(l) + 2000 kJ/mol

H2O2(aq) + OI-(aq) + 1500 kJ/mol --> I-(aq) + H2O(l) + O2(g)

WHICH OF THE THREE ARE ENDOTHERMIC AND WHICH ARE EXOTHERMIC? HOW DO YOU KNOW? (2 SENTENCES)

Closing Time No Homework tonight!