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podryga [215]
2 years ago
8

A system delivers 1275 j of heat while the surroundings perform 855 j of work on it. calculate ∆esys in j.

Physics
1 answer:
kakasveta [241]2 years ago
6 0
The first law of thermodynamics says that the variation of internal energy of a system is given by:
\Delta U = Q + W
where Q is the heat delivered by the system, while W is the work done on the system.

We must be careful with the signs here. The sign convention generally used is:
Q positive = Q absorbed by the system
Q negative = Q delivered by the system
W positive = W done on the system
W negative = W done by the system

So, in our problem, the heat is negative because it is releaed by the system: 
Q=-1275 J
while the work is positive because it is performed by the surrounding on the system:
W=+855 J

So, the variation of internal energy of the system is
\Delta U = -1275 J+855 J=-420 J
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First, I searched the "ionization energy" of Hydrogen on Floogle.  That's how much work it takes to rip the one electron away from its Hydrogen atom, and it's 13.6 eV (electron-volts).

In order to find the frequency/wavelength of a photon with that energy, I need the energy in units of Joules.

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13.6 eV = 2.179 x 10⁻¹⁸ Joule

OK.  Now we can use the popular well-known formula for the energy of a photon:

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or  Energy = h · (light speed/wavelength)

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Wow !  The only thing we don't know in this equation is the wavelength, which is what we need to find.  That's gonna be a piece-o'-cake now, because we know the energy, we know ' h ', and we know the speed of light.

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<em>Wavelength = 9.117 x 10⁻⁸ meter </em>

That's  91.1 nanometers .

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(You have no idea how happy I am with this result.  I figured it out exactly the way I showed you, and I never peeked.  Then, AFTER I had my solution, I went to Floogle and searched to see what it really is, and whether I came out anywhere close.  I found it in the article on the "Lyman Series".  It says the wavelength of the energy released by an electron that falls in from infinity and settles in the n=1 energy level of Hydrogen is  91.175 nm !  This gives me a big hoo-hah for the day, and I'm going to bed now.)

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sergiy2304 [10]

Answer:

The third diagram

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The answer is A. 

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Moreover, for a normal atom, the number of protons in the nucleus is equal to the number of electrons around it.

This means that for a normal atom, the net charge of it is zero, since the total charge of the protons balance that of the electrons.

So, the answer to the question is that the atom is neutral.

Learn more about atoms here:

brainly.com/question/2757829

#LearnwithBrainly

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