{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

10-29-090

# 10-29-090 - Today Today Enthalpies of Reaction are useful...

This preview shows pages 1–11. Sign up to view the full content.

Today: Today: Enthalpies of Reaction are useful Can be calculated for any reaction

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Last time : H 2 ( g ) + ½ O 2 ( g ) H 2 O ( g ) H = - 241.8 kJ You calculated that 13.4 kJ are released for the synthesis of 1g of water. exothermic C 8 H 18 ( l ) + 12 ½ O 2 ( g ) 8 CO 2 ( g ) + 9 H 2 O ( g ) Now : H = - 5461 kJ
C 8 H 18 ( l ) + 12 ½ O 2 ( g ) 8 CO 2 ( g ) + 9 H 2 O ( g ) H = - 5461 kJ

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
C 8 H 18 ( l ) + 12 ½ O 2 ( g ) 8 CO 2 ( g ) + 9 H 2 O ( g ) H = - 5461 kJ How much energy is released by the combustion of 3mL of C 8 H 18 ? Note: Density = 0.688 g/mL Molecular weight = 114 g/mol Answer: - 98.9 kJ
1g of water: * To warm it up by 1 degree: C = 4.184 x 10 -3 kJ * To convert it into steam (at 100˚): H v = 2.3 kJ * To “break” it: H = 13.4 kJ Reminder: So 98.9 kJ should be noisier than last time…

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Where did the 98.9 kJ go? Work Heat Sound C 8 H 18 ( l ) + 12 ½ O 2 ( g ) 8 CO 2 ( g ) + 9 H 2 O ( g ) H = - 5461 kJ Enthalpy change for the combustion of isooctane:
State Functions State Functions E and H are “state” functions. Their value depends only on the state the system is in, not on the path it took to get there. Work and Heat are not “state” functions. Their values depend on the path taken.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Altitude is a state function.   Altitude is a state function.   Distance is not. Distance is not.
Recall once again… Recall once again… Energy diagrams, and activation energy Exothermic process: reactants products E a H < 0

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
CH 4 ( g ) + 2O 2 ( g ) CO 2 ( g ) + 2H 2 O( g ) H 2 O( l ) H 2 O( g ) Simplify Diagram to Just Relative
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}