∆H

Moderators: Chem_Mod, Chem_Admin

Jasleen Kahlon
Posts: 52
Joined: Wed Nov 21, 2018 12:19 am

∆H

Postby Jasleen Kahlon » Sun Jan 26, 2020 11:24 pm

Is looking at ∆H the only way to determine whether a reaction is exothermic or endothermic?

Nicholas Chin 1G
Posts: 100
Joined: Thu Jul 11, 2019 12:17 am

Re: ∆H

Postby Nicholas Chin 1G » Sun Jan 26, 2020 11:26 pm

I'm not sure it's the only way, but it's probably the most reliable way.

MingdaH 3B
Posts: 133
Joined: Thu Jul 11, 2019 12:17 am

Re: ∆H

Postby MingdaH 3B » Sun Jan 26, 2020 11:27 pm

No, you can touch it.

Martina
Posts: 111
Joined: Thu Jul 25, 2019 12:16 am

Re: ∆H

Postby Martina » Sun Jan 26, 2020 11:27 pm

I think that it is, unless you know whether the reaction releases energy or requires it.

Kennedi2J
Posts: 101
Joined: Wed Sep 18, 2019 12:20 am

Re: ∆H

Postby Kennedi2J » Sun Jan 26, 2020 11:29 pm

I think another is by looking at the energy graphs he's gonna cover soon.

Long Luong 2H
Posts: 51
Joined: Thu Sep 19, 2019 12:16 am

Re: ∆H

Postby Long Luong 2H » Sun Jan 26, 2020 11:33 pm

Delta H is a numerical value that is a good indicator of the reaction being endothermic or exothermic. Another way can be to look at the bonds of a reaction. Overall, breaking a bond is endothermic and forming a bond is exothermic.

Alison Trinh 1E
Posts: 104
Joined: Thu Jul 25, 2019 12:16 am

Re: ∆H

Postby Alison Trinh 1E » Sun Jan 26, 2020 11:45 pm

What does DeltaH represent?

Chantel_2I
Posts: 109
Joined: Sat Sep 07, 2019 12:19 am

Re: ∆H

Postby Chantel_2I » Mon Jan 27, 2020 12:23 pm

Often, if you know what kind of reaction it is, you can determine if it is endothermic or exothermic. For example, breaking a bond is usually endothermic.

805097738
Posts: 180
Joined: Wed Sep 18, 2019 12:20 am

Re: ∆H

Postby 805097738 » Mon Jan 27, 2020 12:57 pm

MingdaH 3B wrote:No, you can touch it.


wait what this a serious response lol

Robin Cadd 1D
Posts: 113
Joined: Thu Jul 11, 2019 12:16 am

Re: ∆H

Postby Robin Cadd 1D » Mon Jan 27, 2020 1:59 pm

In general, if heat is used in the reaction, the reaction is endothermic. If heat is released by the reaction, the reaction is exothermic.

Ruby Richter 2L
Posts: 103
Joined: Thu Jul 25, 2019 12:17 am

Re: ∆H

Postby Ruby Richter 2L » Mon Jan 27, 2020 2:41 pm

805097738 wrote:
MingdaH 3B wrote:No, you can touch it.


wait what this a serious response lol


Today in class he did say that if you're using a calorimeter and you touch the outside before and after the experiment you can determine if heat was lost or gained. So yes I think?

haileyramsey-1c
Posts: 105
Joined: Thu Jul 25, 2019 12:18 am

Re: ∆H

Postby haileyramsey-1c » Mon Jan 27, 2020 2:47 pm

Alison Trinh 1E wrote:What does DeltaH represent?


Delta H is the change in enthalpy of the system during a reaction. The delta H can indicate whether the reaction is endothermic or exothermic based on whether delta h is positive or negative. A negative delta H indicates it is exothermic and thermodynamically favorable.

GFolk_1D
Posts: 101
Joined: Fri Aug 09, 2019 12:15 am

Re: ∆H

Postby GFolk_1D » Mon Jan 27, 2020 2:49 pm

There are some instances where you can assume without the actual value such as when you break a bond (endothermic as energy is required to break the bond)

TimVintsDis4L
Posts: 104
Joined: Sat Aug 17, 2019 12:17 am

Re: ∆H

Postby TimVintsDis4L » Mon Jan 27, 2020 3:06 pm

∆H tells us the change in temperature so I don't know what else could tell us if its an endothermic or exothermic reaction.

Mitchell Koss 4G
Posts: 128
Joined: Sat Jul 20, 2019 12:17 am

Re: ∆H

Postby Mitchell Koss 4G » Mon Jan 27, 2020 10:14 pm

You can also see if heat is used as a product or reactant for determining exo/endo thermic

Jainam Shah 4I
Posts: 130
Joined: Fri Aug 30, 2019 12:16 am

Re: ∆H

Postby Jainam Shah 4I » Tue Jan 28, 2020 12:00 am

I believe so delta h would be the most reliable way unless you are given initial, final, or a change in temperature. You can also see whether bonds are being broken or formed in a reaction.

kristi le 2F
Posts: 102
Joined: Thu Jul 11, 2019 12:15 am

Re: ∆H

Postby kristi le 2F » Sun Feb 02, 2020 10:44 pm

You can also look at the temperature change of the surroundings and use that to conclude whether the reaction is exothermic or endothermic. If a reaction is exothermic, it releases heat into surroundings. If a reaction is endothermic, it absorbs heat from the surroundings.

Trent Yamamoto 2J
Posts: 111
Joined: Sat Aug 17, 2019 12:18 am

Re: ∆H

Postby Trent Yamamoto 2J » Sun Feb 02, 2020 10:52 pm

Delta H is the easiest to determine if a reaction is positive or negative


Return to “Phase Changes & Related Calculations”

Who is online

Users browsing this forum: No registered users and 1 guest