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? NH 4 NO kJ/mol  HNO 3 + NH 3

Table Talk  Is the following reaction endo- or exothermic? 2H 2 + O 2 → 2H 2 O 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. C 6 H 12 O 6 (aq) + 6O 2 (g) → 6CO 2 (g) + 6H 2 O (l) kJ/mol

Summarize

Work Time Complete the worksheet with your table.

Exit Slip  Elephant Toothpaste Chemistry: Ever wanted to make elephant toothpaste?  The overall equation for this reaction is:  2 H 2 O 2 (aq) --> 2 H 2 O(l) + O 2 (g) kJ/mol  However, the decomposition of the hydrogen peroxide into water and oxygen is catalzyed by the iodide ion.  H 2 O 2 (aq) + I - (aq) --> OI - (aq) + H 2 O(l) kJ/mol  H 2 O 2 (aq) + OI - (aq) kJ/mol --> I - (aq) + H 2 O(l) + O 2 (g)  WHICH OF THE THREE ARE ENDOTHERMIC AND WHICH ARE EXOTHERMIC? HOW DO YOU KNOW? (2 SENTENCES)

Closing Time  No Homework tonight!