Help with enthalpy
 User Name Remember Me? Password
 FAQ Calendar Search Today's Posts Mark Forums Read

 Thread Tools Display Modes
#1
October 11th, 2005, 17:16
 Miriama Junior Member Join Date: Sep 2005 Posts: 5
Help with enthalpy

1. The bombardier beetle uses the following explosive reaction as a defence mechanism. The product acts as a repellent.

C6H4(OH)2 + H202 -> C6H4O2 + 2 H20

Calculate the enthalpy change for the above reaction using the following information equations.
1. C6H4O2 + H2 -> C6H4(OH)2 delta Hr = -177.4 kJ
2. 2 H20 + H2 -> O2 + 2 H20 delta Hr = -189.0 kJ
3. 1/2 O2 + H2 -> H20 delta Hr = -285.8kJ

I understand that we have to come out with the net equation, but somehow my calculations aren't able to cross components out.

So you think you might be able to help me, and if so show me the work?
Thank you.[/img]
#2
October 11th, 2005, 18:01
 charco Member Join Date: Mar 2005 Posts: 69

required: C6H4(OH)2 + H202 -> C6H4O2 + 2 H20

available:
1. C6H4O2 + H2 -> C6H4(OH)2 delta Hr = -177.4 kJ
2. 2 H20 + H2 -> O2 + 2 H20 delta Hr = -189.0 kJ
3. 1/2 O2 + H2 -> H20 delta Hr = -285.8kJ

your equations are not balanced

2. should (probably) read
2H202 -> O2 + 2 H20

if you don't copy the equations down correctly then you have no chance!
#3
October 11th, 2005, 18:05
 Miriama Junior Member Join Date: Sep 2005 Posts: 5

Yes, I've realized. And thank you for the prompt reply.

I had already figured out my mistake.

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is Off Forum Rules
 Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Science, Technology & Devices     General Discussion     Periodic Table     Organic Chemistry

All times are GMT -5. The time now is 09:09.

 Contact Us - Periodic Table - Archive - Top

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2013, vBulletin Solutions, Inc.