## When does delta U equal zero?

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charlotte_jacobs_4I
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### When does delta U equal zero?

What are the rules for delta U = 0? When does this happen? Under what circumstances?

aisteles1G
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### Re: When does delta U equal zero?

whenever its stated that a reaction is isothermal (reversible or nonreversible) you can assume that delta U = 0

Laurence Tacderas 1K
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### Re: When does delta U equal zero?

Since deltaU=3/2nRT, if the reaction is at constant temperature, the internal energy will be equal to zero

504909207
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### Re: When does delta U equal zero?

When work =0 and it is a adiabetical process, meaning that q=0.

Letizia Ye 4F
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### Re: When does delta U equal zero?

If the reaction is isothermal, delta U=0.

Alexandra Albers 1D
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### Re: When does delta U equal zero?

In an isothermal reaction, delta U will be 0. Since this is the case, you will also know that q=-w or w=-q, so you can easily calculate one if you know the other.

chris_tsai_4H
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### Re: When does delta U equal zero?

When a reaction is isothermal, delta U (internal energy) equals zero.

amogha_koka3I
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### Re: When does delta U equal zero?

Do we assume isothermal, reversible, and at equilibrium are all synonymous in this class?

harshitasarambale4I
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### Re: When does delta U equal zero?

I'm not sure if we can equate isothermal to equilibrium.

maldonadojs
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### Re: When does delta U equal zero?

deltaU=0 when there is a constant temperature, or when temperature is 0. This is because of the equation U=3/2nRT. If constant temperature, Tf-Ti=0. However, if temperature=o, the equation would equal zero instantly.

Sean_Rodriguez_1J
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### Re: When does delta U equal zero?

I would just like to add that while delta U equals zero in an isothermal process (or in any isolated system), the two have no change in U for different reasons. In an isothermal process, the energy exchanged as heat (q) equals the amount of work done by the system (q = -w) so any heat energy from the process is cancelled out by work, and consequently delta U is 0. In an isolated system, no energy (either as work or as heatI is transferred, so q=0, w=0, and delta U = 0.

Hadji Yono-Cruz 2L
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### Re: When does delta U equal zero?

In an isothermal reaction then delta U is zero.

Maya_Peterson1C
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### Re: When does delta U equal zero?

This is for an isothermal reaction. (We can also infer from this that q=-w)

Shibhon_Shepard
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### Re: When does delta U equal zero?

if the problem states that it is isothermal, q=0 and q=-w, since delta U = q+w, 0+0=0

Jeannine 1I
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### Re: When does delta U equal zero?

amogha_koka3I wrote:Do we assume isothermal, reversible, and at equilibrium are all synonymous in this class?

I believe that we can assume (for this class) that isothermal also means reversible. I don't think we can assume it's at equilibrium though.

Casandra
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### Re: When does delta U equal zero?

delta U is equal to zero when the reaction is isothermal, meaning temperature is constant.

Desiree1G
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### Re: When does delta U equal zero?

When the reactions says it is isothermal that means that the temperature is constant (iso=same). If this is the case then there is no change in the internal energy therefore U is 0.

LeannaPhan14BDis1D
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Joined: Fri Sep 28, 2018 12:16 am

### Re: When does delta U equal zero?

When the reaction is isothermal

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