Heats of Reaction and Hess's Law

Heats of Reaction and Hess's Law

By: Grace Kilpatrick

Hi everyone! I hope you all are having a wonderful Thursday! Here is how class went today...

-First, Mrs. Friedmann checked in last night's homework. This was the Hess's Law-Practice worksheet and the Hess's Law worksheet, both which can be found in the Unit 8 Handouts folder. Due to time constraints, we did not have time to go over these in class. However, it is part of the homework to check the answer key to these worksheets, which is labeled as 5_Key_to_Hesss_Law_HW.pdf in the Unit 8 Keys Folder.

-Next, we went over the Heats of Reaction and Hess's Law pre-lab. These are the notes:

-For the rest of the period, we worked with a partner to collect experimental data for the Heats of Reaction and Hess's Law Lab. Mrs. Friedmann has uploaded lab data to use if you were absent in the Unit 8 Labs and Activities. This is my group's data. The upper portion is that data collected for reaction #1, where the lower portion is that data collected for reaction #2.

HOMEWORK:

-Check last night's homework with the answer keys online.

-See Webassign for the "Chapt. 9.1-2 - Solids and Liquids - Rdg Sheet" assignment due March 4th, at 11:59 PM

-Begin working on write up for today's lab-likely to be due Tuesday.

The next blogger will be...Juliette O.!

Hess's Law

Hess's Law

Today we went over Hess's law. Mrs. Friedmann's thorough and very helpful notes on it can be found here.

Tonight's homework is a webassign if you didn't do it yesterday (due tonight at 11:59) and three handouts on Hess's law (really two, but one is two pages). The first can be found here and the second here, but neither of them can be found here.

The net blogger is: Grace K!

Thermochemistry and Phase Diagrams (2/24/14)

Today in class, we reviewed and went over the answers to the packet Mrs. Friedmann gave us in class on Friday.  After going over the packet, we started to take notes on Phase Diagrams.  Mrs. Friedmann said that the packet and notes would be on Moodle.  Our homework was to do the two worksheets we picked up in class on Phase Diagrams.
The next blogger is Brandon M.

Thermochemistry - Putting Some Pieces Together

Thermochemistry - Putting Some Pieces Together

February 21st, 2014

Hayden Northwick

Today Mrs. Friedmann wasn't here, so we worked on a packet during class.  If the packet isn't finished by the end of class, it is homework.  Also the last two WebAssigns are re-opened for the duration of the weekend.  They close on the 23rd at 11:59PM.

The next blogger is:
Peter

Heats of Formation

Scribe Post Author: Serene P.

February 19, 2014

Starting off class today, there was no homework to be checked in. Ms. Friedmann reminded us of our homework and informed us that we should do our best to complete our lab calculations independently.  Our homework due tomorrow includes:

Heats of Formation worksheet(with using the two sheets of Thermodynamic Data)

Webassign 8.3-8.4 due by 11.59 tonight

Watch a video Ms. Friedmann posted on moodle. http://vimeo.com/59855650 This will go over the two prelab questions for the lab to be performed tomorrow in class. If you are to be absent, here is the link to the worksheet of the lab with data. http://gbs-moodle.glenbrook225.org/moodle/file.php/12015/1314_Unit_8_--_Thermochemistry/Unit_8_Labs_and_Activities/2.19_Heat_of_Formation_Lab_with_Data.pdf

Heat of combustion lab write-up due tomorrow

During class today, we took notes on Heat Formation. Here are the notes: (Sorry! The diamond shaped figures with question marks in them were supposed to be triangles. I don't know how it occurred to be like this on the blog. Sorry again!)

Heats of Formation

4 NH3(g) + 7 02 → 4 NO2(g) + 6 H2O(l)

🔺H rxn= -1396KJ

4 NH3(g) + 7 O2 ---> 4 NO2(g) + 6 H2O(l)

*🔺H f (heat of formation) = The energy it takes to ‘form’ a COMPOUND from the elements that make it up.

*🔺H f often times, it’s exothermic. Sometimes its positive!

*🔺H f of an element (in its stable state) = 0KJ/moles

Examples: Na, H2, O2, Mg...etc.

*Units are KJ/moles

------------------------------------------------------------------------------------------------------------------

🔺 H reaction= sum of 🔺H f products - sum of 🔺 H f reactants

🔺 H reaction= (4 moles x (+33.2 KJ/moles)) + (6 moles x (-285.8 KJ/moles)) - (4 moles x (-46.1 KJ/moles)) + (7 moles x (0 KJ/moles))

=(132.8 KJ - 1714.8 KJ) - (-184.4 KJ)

=-1582KJ + 184.4 KJ

= -1397.6 KJ

Here is a picture of the Thermodynamic Data (Please remember that not all data tables of these values will be identical):

After completing out notes for the day, Ms. Friedmann gave us time to work on our homework. We may look forward to completing another lab tomorrow that will not require a complete write-up but will have post-lab questions to be completed.

Thanks!

Next Post Author: Hayden

Lab: Heat of Combustion

Lab: Heat of Combustion

2/18/2014:

           After Mrs. Friedmann checked in the homework, we went over the pre-lab questions (blue sheet). Some of these questions were new to the unit and proved to be challenging. The key to these questions can be found on moodle here. We then moved on to the lab for today.

The Lab:

           The Heat of Combustion Lab involved hanging a can of water over a burning candle, all inside a calorimeter. Some of the data we kept note of was the difference in water temperature and the difference of candle mass. For the purposes of the lab write-up, we are basing our calculations on the assumption that all the heat lost by the candle was gained by the water. Since our heat formula can't be used for the heat energy of the candle, we were told to instead find the heat gained by the water and assume this was the same as the heat lost by the candle. 

          For this lab, we will also need to use a formula for the combustion reaction that took place. This should include heat as one of the products and the use of C25H52 (paraffin) for the candle.

The homework for tonight is:

1) The lab write up is due Thursday

2) There is a new webassign due by Wednesday night

Tomorrow's scribe is:

Serene P.

2/14/14

Thermochemistry and Other Long Words

By: Kevin Mihelic

We started class by collecting a valentines day gift from Mrs. Friedmann. This gift was filled with baking soda and vinegar and to inflate it we had to step on it. I had some trouble with this. We picked up 3 sheets. One was a lab, one was a sheet of calculations to do for homework. The homework due on Tuesday is:

1. Check Fridays homework with key posted on moodle.
2. WebAssign on heating curves
3. Finish Calorimetry pre-lab (blue sheet) -- find on moodle
4. Watch video on Enthalpy video on moodle and take notes.

For notes on Energy Diagrams and Activation energy click here- http://gbs-moodle.glenbrook225.org/moodle/file.php/12015/1314_Unit_8_--_Thermochemistry/Unit_8_Notes/2.14_Notes_on_Energy_Diagrams_and_Enthalpy.pdf

For the key to fridays homework here- http://gbs-moodle.glenbrook225.org/moodle/file.php/12015/1314_Unit_8_--_Thermochemistry/Unit_8_Keys/Key_to_Heating_Curve_Calcs_Ws.pdf

For the Calorimetry prelab- http://gbs-moodle.glenbrook225.org/moodle/file.php/12015/1314_Unit_8_--_Thermochemistry/Unit_8_Handouts/2.14_Heat_of_Combustion_Pre-Lab.pdf

On this sheet there are two difficult problems. These problems will be discussed in the comment section below this post. Please help even if you have trouble doing it- anything can help.

Fingers crossed for no school tomorrow!!!

Next Blogger is Brandon M.