All Questions
Tagged with notation thermodynamics
7 questions
36
votes
6
answers
32k
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Why do chemistry and physics have different sign convention in thermodynamics?
In physics class, we write the first law of thermodynamics as $\mathrm dU =\mathrm dQ - \mathrm dW$ and in the physical chemistry class, we write the same law as $\mathrm dU =\mathrm dQ + \mathrm dW$. ...
user31607
11
votes
1
answer
4k
views
Why was a Plimsoll symbol chosen to indicate standard state?
Historically, the Plimsoll symbol (aka Plimsoll line) was created as hull mark that would serve as a ready indicator of whether a ship was overloaded and thus running too low in the water. It was ...
- 12.3k
6
votes
3
answers
16k
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kJ per mole or kJ per 2 moles?
From Chemguide:
Here is a simple reaction between hydrogen and oxygen to make water:
$$\ce{2 H2(g) + O2(g) -> 2 H2O(l)} \quad \Delta_\mathrm{r}H^\circ = \pu{572 kJ mol^-1}$$
First, notice that ...
- 3,292
5
votes
0
answers
125
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Is a change in delta-delta-G typically notated as delta-delta-delta-G?
I'm currently writing a research paper, and need to refer to a difference between $\Delta{\Delta}G$s. The naive way to notate this would be $\Delta{\Delta}{\Delta}G$, but that looks cumbersome and ...
- 61
2
votes
1
answer
1k
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Gibbs Free Energy Notation
What's the difference between $G$, $\Delta G$, $\Delta G^\circ$, and $\Delta_\mathrm r G^\circ$?
I've seen the first two used interchangably, and seen $G$ specifically referred to as change in Gibbs ...
- 133
2
votes
1
answer
80
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Meaning of the symbol “$\Delta_\mathrm{sub}H^\circ[\ce{I2,s}]$”
One of the back exercises (13(C)) from the book for practice provided at my school asked whether the following relation is true:
$\Delta_\mathrm{f}H^\circ(\ce{I2,g}) = \Delta_\mathrm{sub}H^\circ[\ce{...
- 113
2
votes
0
answers
515
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Why is U the symbol for lattice energy?
I often see $U$ or even $\Delta U$ being the symbol for lattice energy. Why is that? Does it refer to internal energy?
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