Delta H naught VS delta H

[Jeffrey Hablewitz 2I]

What is the difference between ΔH and ΔH°?

[Ashlen Bullock 1H]

I think delta H naught is delta H at standard conditions (1 atm, 298K, 1M solution). Delta H is just the enthalpy of change of a reaction/ physical change.

[David Chibukhchian 2G]

Delta H naught can be thought of (for example) the delta H of a reaction when a substance is made from its elements in its standard states. For example, if we have a reaction like N2 + 3H2 -> 2NH3, then the delta H can include the naught because the substance NH3 is made out of diatomic hydrogen and nitrogen (which are their standard states). Delta H naught is used in the equation delta G naught = delta H naught - T*delta S naught, that's why we talk about it in this unit. That's basically what I have gathered so far, I hope that helps!

[Eileen Quach Dis 2A]

ΔH° is the change in enthalpy under standard conditions, while ΔH is just the change in enthalpy.

[Kayle Lim 2C]

Hi, there's a recent post asking about the different between G naught and G and I am pretty sure the answers are the same for this question where the naught just represents standard conditions. Problems probably use the naught notation as a way of indicating that enthalpy is under standard conditions instead of specifying "1atm, 298K, 1M solution" all the time and when the naught isn't present students could assume conditions are not standard and work around that.

Hope this helps!

[Megan Hulsy 1A]

ΔH* means that it is conducted under standard condtions (298K, 1atm). This can be said about ΔG and ΔS as well! :)

[Jeffrey Hablewitz 2I]

Thanks! All your responses were very helpful.

[Mary Shih 3J]

the knot means its under standard conditions. 298k and 1 atm

[austin-3b]

Delta H naught is just the specific standard conditions.

[haley f]

ΔH naught is the change in enthalpy under standard conditions and ΔH is just the change in enthalpy!

[Jaden Joodi 3J]

Most have already mentioned that H° is H at standard conditions, but I just wanted to add that I think Dr. Lavelle mentioned that whenever we see the ° symbol, that it always means standard conditions.

[Uyen Trinh 3C]

Generally, whenever there is ° it means under standard conditions of 1 atm and at 298K.

Similarly, standard Gibbs free energy of reaction (ΔG°) and standard entropy (ΔS°) are given to us in tables that are defines as under standard conditions.

[Jeffrey Hablewitz 2I]

Thank you for all the responses!

[Karl Yost 1L]

A naught indicates that the variable (whether it be entropy, cell potential, enthalpy or Gibbs free energy) is being measured at standard temperature and pressure. Typically, this is 298K (varies based on the textbook), 1 atm and, in the case of E cell naught values, 1M solutions.

[Muskaan Abdul-Sattar]

ΔH° actually represents ΔH at standard conditions, while ΔH represents the change in enthalpy.

[Jeremy Wei 2C]

The "naught" is used to indicate standard conditions, so delta H naught would be change in enthalpy under standard conditions, while delta H is just change in enthalpy in general.

[Diana Aguilar 3H]

Hi! Like many have stated, delta H naught represents change in enthalpy under standard conditions and delta H just represents change in enthalpy.

[Queena Chu 3E]

° indicates standard conditions!

[Nishan Reddy 3K]

∆H is usually just for standard enthalpy for a reaction while ∆Hº is for the reaction at standard conditions.

[Do Yeun Park]

Delta H naught means it's under standard condition!

[Arjan G 2H]

Hi! Whenever there is a degree sign on entropy, enthalpy, or free energy, it means it is naught, which can be considered the standard rate of a given concept. So, delta H naught represents the enthalpy of a substance given standard conditions of 1 atm Pressure, 298 Kelvins, and constant volume. Delta H is a more broad definition, meaning it can be used to signify the enthalpy of a substance under any given conditions. I hope this helps!

[Cadence Chang]

∆H naught is the change in enthalpy of a reaction done at standard temperature and pressure (298 K and 1 atm). ∆H refers to the enthalpy of reactions done at nonstandard conditions where the temperature and pressure can vary.

[Naomi Christian 1E]

Delta H naught is the standard enthalpy at standard conditions (298 K, 1 atm.) Delta H is the enthalpy at nonstandard conditions.

[daniellediem1k]

Delta H naught is the same as delta H just at STP

[Michelle Argueta 1E]

Delta H naught is when the system is in standard conditions (the standard enthalpy) which falls in a temperature of 298 K and 1 atm pressure. The delta H is the enthalpy at nonstandard conditions.

[Sarah Hong 2K]

DelaH naught is the change in entropy under standard conditions (1atm) and deltaH is just the change in entropy.

[Alejandra Hernandez 2A]

In this context, ΔH° is the change in enthalpy when conducted under standard conditions. And ΔH is just the change in enthalpy with no specifications.

[Amy Jordan 2A]

Hi, delta H naught means delta H (change in enthalpy) under standard conditions, while delta H is just change in enthalpy.

[Valerie Jun 2D]

I think that any delta (blank) naught value represents the value of something at perfect standard conditions and delta (blank) represents the value of something at "non-perfect" conditions. Kind of like K and Q from equilibrium!