delta U= delta H

[Emily Vainberg 1D]

When does the Internal Energy (delta U) = delta H?

[Jessica Castellanos]

I think, at constant volume and constant pressure, delta U is equal to delta H.

[Dina Marchenko 2J]

When there is a constant volume or pressure, no expansion or compression work is being done by the system so w=0. When heat is at constant pressure, it equals the enthalpy change, so at constant pressure, delta U is equal to delta H.

[Rebekah Alfred 1J]

When the volume of the reactants is equal to the volume of the products, delta U is equal to delta H.

[Kayla Maldonado 1C]

Delta U= q+w and under constant pressure, q_p=delta H and when no work is done Delta U=Delta H

[Leonardo Le Merle 1D]

The answers to this question
viewtopic.php?t=25381
Were also pretty helpful for me sorting it out in my head, hope they help!

[Jacob Motawakel]

under constant volume delta U equals delta H because at constant pressure q equals H and at constant volume no work is being done, so in that case U=q which is U=H in contact pressure and volume.

[Frankie Mele 3J]

The standard equation deltaU=deltaH - P*deltaV accounts for any change in the volume, however, when delta V = 0, the equation changes to deltaU=deltaH - P*0. This is when deltaU=deltaH because P*0 will not affect the internal energy (delta U).

[arisawaters2D]

Just to clarify, delta U=delta H when pressure and volume are constant and no work is being done?

[SamanthaTolentino 3D]

Just to clarify, delta U=delta H when pressure and volume are constant and no work is being done?

yeah if we have constant volume, delta U is equal to qv and when we have constant pressure delta U is equal to qp. As a result we have delta U = delta H - PdeltaV. However, if P and V are constant then we just have delta U=delta H

[Tanya Nguyen 1B]

Just to clarify, delta U=delta H when pressure and volume are constant and no work is being done?

yeah if we have constant volume, delta U is equal to qv and when we have constant pressure delta U is equal to qp. As a result we have delta U = delta H - PdeltaV. However, if P and V are constant then we just have delta U=delta H

So substituting delta U = q + w, how is q equal to delta H when pressure is constant?

[Ximeng Guo 2K]

When there is no change in volume, there is no delta w, delta U = delta H

[Rahul Sobti 1E]

When there is constant pressure on no work done by expansion the DeltaU = DeltaH

[Jason Knight - 1F]

Delta U is equal to delta H when there is no change in volume, so that means that work equals zero. This is because no expansion or compression is done, and work equals zero.

[Brandon Le 3C]

We can only say that delta U = delta H when there is no work done on the system. This means that there will be no change in volume and no change in pressure.

[Madeline Louie 1B]

When there is constant pressure and a constant volume, delta U is equal to delta H.

[Sofia Lombardo 2C]

when there is no work (work = 0). This occurs when there is constant volume (since the work equation =.

[Jiapeng Han 1C]

When there is no work done. In other words, delta U=delta H when there is no change in volume, ex. in an ideal gas.

[emwoodc]

This means that when there is constant pressure AND constant volume, delta H (enthalpy) equals delta U

[Joshua_Chan_3K]

The easy way to remember this is that work is equal to force times distance. Distance in our case is when a plunger or something similar is usually pushed into the chamber or out of the chamber which changes the volume. Therefore when their is no change in volume, work = 0. Once work = 0 the only thing left in the equation is delta U = change in enthalpy.

[Elizabeth Kaplan 3I]

Internal energy equals change in enthalpy at constant pressure and volume. This is because internal energy equals q (heat) at constant volume (since the system is not doing any work), and q equals delta H at constant pressure.

[Hasan Mirza 3F]

As long as Pressure and Volume are constant, they are equal because no work is being done.