Lon-Capa

1 / 11

# Lon-Capa - PowerPoint PPT Presentation

Lon-Capa. 4 th HW assignment due Friday, 10/10, 5 pm. It is open now. 3 rd Quiz due Sunday, 10/12 by 10 pm. It will open Friday, 10/10 at 5 pm. Clicker Question. The following chemical reaction is exothermic: A 2 + B 2  2AB. This means: more stable higher average bond energies

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

## PowerPoint Slideshow about ' Lon-Capa' - makaio

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Lon-Capa
• 4th HW assignment due Friday, 10/10, 5 pm. It is open now.
• 3rd Quiz due Sunday, 10/12 by 10 pm. It will open Friday, 10/10 at 5 pm.
Clicker Question

The following chemical reaction is exothermic: A2 + B2 2AB. This means:

more stable higher average bond energies

a) Reactants Reactants

b) Reactants Products

c) Products Products

d) Products Reactants

e) I do not know.

Some Big Ideas
• Low energy  low in potential energy  more stable.
• If a system absorbs energy, the natural tendency is to release it.
• That is, achieving low potential energy is “natural”.
• Ground state preferred over excited state.
• Energy is converted from one form to another but is NOT created nor destroyed.
• First law of thermodynamics.
• Energy is a state function (heat and work are not).
Determining Hrxn
• Since H = qp, measure the heat given off or required at constant pressure. This is termed calorimetry.
• Since energy is conserved, we can often determine Hrxn for one reaction given values of Hrxn for others. Uses the principle in Hess’s Law.
• Use standard enthalpies of formations for reactants and products (we have tables of these).
Clicker Question

You drop 50.0 g of 100.0C metal into 100.0 g of 22.0C water. The final temperature of the water is 29.5C. Identify the metal.

c(water) = 4.18 J/g C

a) aluminum (c=0.89J/gC)

b) iron (c=0.45J/gC)

c) copper (c=0.20J/gC)